The complete BIOS beep guide

TANDON Beep Codes:

Tandon Type A AT 29 Feb 1988 BIOS Post Codes:
01 Test 80286 CPU flags and registers
02 Test BIOS ROM checksum
03 Test MC 146818 CMOS RAM battery - real time clock
04 Test 8254 programmable interrupt controller
05 8254 programmable interrupt controller test failed
06 Initialize RAM refresh
07 Test first 16K RAM
08 Initialize cold boot interrupt vectors
09 Test 8259 programmable interrupt controller and interrupt vectors
0A Fill in temporary interrupt vectors
0B Initialize interrupt vector table 1
0C Initialize interrupt vector table 2
0D Initialize fixed disk vector
0E Interrupt vector test failed
0F Clear keyboard controller input buffer
10 Keyboard controller input buffer clearing failed
11 Run keyboard controller self test
12 Initialize equipment check data area
13 Determine presence of and install 80287 math coprocessor
14 Test MC 146818 CMOS RAM disk value range
15 Test for and install parallel port
16 Test for and install serial port
17 Call interrupt 19 boot loader

Return to Top

Tandon Type B AT 1992 BIOS Post Codes:
01 Cold boot started
06 Initialize chipset if any
07 Warm boot entry; Start of 8042 keyboard controller self test
08 Part of cold boot keyboard initialization passed
09 Keyboard self test passed; Test CMOS checksum
0A Test CMOS RAM battery
0B Save CMOS RAM battery condition in CMOS diagnostic/status register
0C Finished saving CMOS RAM battery condition
0D Test 8254 programmable interrupt timer; Disable RAM parity, I/O parity, DMA controllers and system speaker; Enable timer channel 2
0E 8254 programmable interrupt timer test failed, xx is the failing channel number
0F Initialize 8254 programmable interrupt timer channels; Conduct memory refresh test
10 Refresh test failed
11 Test base 64K RAM and fill with zeros
12 64K RAM test failed - 3 long beeps and system halt
13 64K RAM test passed
14 Set up stack; Disable mappers for systems that support EMS drivers; Initialize battery beep flag parameters for notebook; Perform read/write test of CMOS RAM; Enable error message if failed
15 CMOS RAM read/write test complete
16 Calculating CPU speed; May set to low if CMOS RAM failed
18 Test and initialize both 8259 programmable interrupt controllers
1A 8259 programmable interrupt controllers initialization complete
1B Install interrupt handler and vector for interrupt 0F to check for unexpected interrupts; Halt is unexpected interrupt occurs
1C Unexpected interrupt did not occur; Test 8254 programmable interrupt timer channel 0, IRQ 0 and software interrupt 8 tests
1D Error; Timer 0 interrupt did not occur when expected, system is halted
1E Both 8259 programmable interrupt controllers passed the tests
20 Set up interrupt vectors 02-1F
21 Set up interrupt vectors 70-77
22 Clear interrupt vectors for 41 and 46
23 Read 8042 keyboard controller self test result; DMA page register channel 2
24 Test for proper 8042 keyboard controller self test result
25 Error; Keyboard controller self test failed; System id halted with message displayed
26 Keyboard controller self test passed
27 Confirm DMA working; Prepare DMA channel 2 for floppy data transfer
28 Reinitialize video
29 Reinitialize video with cursor off
2A Video parameters are initialized
2B Enable NMI and I/O channel check; Disable 8254 programmable interrupt timer channel 2 and speaker
2C Run RAM test to determine size of RAM
2D RAM sizing complete
2E Send reset command to keyboard controller to initialize a keyboard scan cycle
2F Keyboard has been initialized; Initialize CMOS real time clock
30 CMOS real time clock has been initialized; Initialize on board floppy if any
31 Install the hard disk controller
32 Disk controller has been initialized; Prepare DMA channel 2 for floppy transfers
33 Perform equipment check and initialize math coprocessor
34 Install the serial and parallel ports
35 Test CMOS RAM battery
36 Check for keystroke
37 Enable 8254 programmable interrupt timer channel 0 for system tick; Enable keyboard and slave interrupt controller 8259 programmable interrupt controller 2
38 Timer tick, keyboard and 8259 programmable interrupt controller 2 have been initialized; Enable/disable cache through CMOS RAM
39 Enable keyboard interface and interrupts; Go to built in setup program as necessary; Shadow ROM's found
3A Set up complete
3B Test the hard disk and floppy disk
3C Scan for and invoke the adapter ROM's in C800-E000
3D Turn of gate A20; Restore vectors 3bh-3fh with temporary interrupt service routines
3E Gate A20 turned on
3F Call interrupt 19 boot loader

Return to Top

Tandon 486 EISA 1989 BIOS Post Codes:
01 Disable cache, enable ROM, high speed on, turn off cache's, disable EISA NMI's, set master/slave IRQ's to edge triggered, disable reset chaining; Disable 82C601 chip
05 Initialize address decoder, 640K RAM; Set BIOS as cacheable, enable extended memory
06 Clear shutdown flag
07 8042 keyboard controller test; Wait till 8042 buffer empty; Disable 8042 command, read 8042 output buffer; Set response ok to DMA page register channel 2
08 Send 8042 keyboard controller NOP command; Get 8042 self test result; Send DMA page register channel 2; If xx=55, then self test ok
09 Test BIOS ROM checksum
0A Read CMOS registers 3 times to clear pending CMOS real time clock interrupts; Disable real time clock interrupts; Check battery
0B Bad CMOS RAM battery
0C Send command to port 61 to disable parity and speaker
0D Test 8254programmable interrupt timer counter
0E One of the counter timers is bad; xx indicates the bad counter
0F Enable and check memory refresh
10 Memory refresh failed
11 Check and clear the first 64K RAM in real mode; Disable NMI; Clear parity latches; Fill 64K with 5555 and check it, then AAA and check it, then 0000
12 First 64K RAM memory test failed
13 First 64K RAM memory test passed
14 Reset the warm boot flag and test CMOS RAM; Turn off caches; Shadow the BIOS; set high speed; Calculate high speed and initialize GP flag; Set low speed and turn off cache if CMOS not good or CMOS speed not high
16 Check shutdown flag 123x
17 Reset was cold boot
18 Prepare 8259 programmable interrupt controllers
19 8259 programmable interrupt controllers initialization failed; Initialize video and display the error message
1A Test 8259 programmable interrupt controller
1B Set interrupt 0F to unexpected interrupt vector; Enable timer and interrupt
1C Set interrupt 08 to timer 0 interrupt vector
1D Timer interrupt did not occur; Initialize video and display error message
1E Initialize interrupt vectors
1F Initialize interrupt vectors 00-6F to temporary interrupt service routines
20 Set vectors for interrupt 02-1F
21 Set interrupt vectors for 70-77, clear vectors 60-67 and 78-FF
22 Clear interrupt vectors for 41 and 46
23 Read 8042 keyboard controller self test results from DMA page register channel 2
24 Test for proper 8042 keyboard controller self test result
25 8042 keyboard controller self test failed
26 Initialize 8042 keyboard controller
27 Check shutdown flag=123x; If no=cold boot
28 If cold boot or CMOS RAM is bad, then install video ROM and initialize video; Initialize equipment flags according to primary video adapter and CMOS RAM content; Initialize POST status
29 If not cold boot and CMOS RAM ok; Install video ROM and initialize video for mono/CGA; Initialize equipment flags according to primary video adapter and CMOS RAM contents
2A Check for bad CMOS RAM
2B Check shutdown flag=123x
2C If cold boot; Turn off caches; Test memory for size and reinitialize cache status
2D Turn off "POST fail" CMOS RAM bit and display and error messages; Initialize keyboard RAM
2E Initialize 8042 keyboard controller and test keyboard
2F Initialize time of day in real time clock
30 Test for and install floppy drive controller
31 Enable 82C601 IDE interface; Test for and install hard disk
32 Test 8259 programmable interrupt controller DMA registers with 55 then AA, then initialize them to 00
33 Test for and initialize math coprocessor
34 Test for and initialize parallel and serial ports
35 Initialize RAM variables for bad CMOS time, date, checksum and battery
36 Wait for user to press Esc or Space; Check for keyboard lock; Clear keyboard lock override; Beep to indicate speed; Display error messages
37 Enable system clock tick (IRQ 0); Enable keyboard (IRQ 1); Enable slave interrupt controller (IRQ 2)
38 Initialize RAM variables for Ctrl-Alt_Esc
39 Enter setup is keystroke pressed
3A Clear screen and update equipment flags according to CMOS RAM contents; Shadow ROM's; Enable/disable cache through CMOS RAM
3B Initialize floppy and hard drives
3C Set POST failed bit in CMOS RAM; Scan for and initialize adapter ROM's
3D Clear the shutdown flag to 0; Disable gate A20 and enable memory wrap in real mode
3E Set vectors for interrupts 3B-3F; Clear post fail bit in CMOS RAM
3F Call interrupt 19 boot loader

SUPERSOFT Beep Codes:



XT BIOS
11 CPU register or logic error
12 ROM POST checksum error
13 8253 programmable interrupt timer channel 0 error
14 8253 programmable interrupt timer channel 1 error
15 8253 programmable interrupt timer channel 2 error
16 8237A DMA controller error
17 8255 parity error detected
18 16K RAM critical region error
19 Memory refresh error
1A -
21 8259 interrupt controller error
22 Unexpected interrupt detected
23 Interrupt 0 (timer) error
24 Nonmaskable interrupt error
25 MDA video memory error
26 CGA video memory error
27 EGA/VGA memory error
28 8087 math coprocessor error
29 Keyboard controller error
2A -
31 Keyboard scan lines/stuck key
32 Floppy controller error
33 Floppy disk read error
34 Memory error at address x
35 Slow refresh, address x
36/37 -
38 -
41 BIOS ROM checksum error
42 BASIC ROM 1 checksum error
43-45 Basic ROM 2,3,4 checksum error




AT BIOS
11 CPU register or logic error
12 ROM POST A checksum error
13 ROM B POST checksum error
14 8254 programmable interrupt timer channel 0 error
15 8254 programmable interrupt timer channel 1 error
16 8254 programmable interrupt timer channel 2 error
17 8237A DMA controller 1 error
18 8237A DMA controller 2 error
19 DMA page registers error
1A 8042 parity error detected
21 16K RAM critical region error
22 Memory refresh error
23 CPU protected mode error
24 8259 programmable interrupt controller 1 error
25 8259 programmable interrupt controller 2 error
26 Unexpected interrupt detected
27 Interrupt 0 (timer) error
28 CMOS real time clock error
29 Nonmaskable interrupt error
2A 8087 math coprocessor error
31 Keyboard controller error
32 Stuck key or CMOS RAM error
33 Floppy controller error
34 Floppy disk read error
35 MDA video memory error
36/37 CGA, EGA/VGA RAM error
38 BIOS ROM checksum error
41 Memory error at address x
42 Slow refresh, address x
43-45 Display pass count
59 No monitor

OLIVETTI Beep Codes:



Olivetti 1076/AT&T BIOS Post Codes:
PASS FAIL DESCRIPTION
41 7F CPU flag and register test
42 7E Check and verify CMOS shutdown code
43 7D BIOS ROM checksum test
44 7C Test the 8253 timer
45 7B Start memory refresh
46 7A Test the 8041 keyboard controller
47 79 Test the first 8KB of RAM
48 78 Test protected mode operation
49 77 Test CMOS RAM shutdown byte
4A 76 Test protected mod operation
4B 75 Test RAM from 8KB to 640KB
4C 74 Test all RAM above 1MB
4D 73 Test NMI
4E 72 Test RAM parity system
50 71 Test 8259 PIC 1
51 6F test 8259 PIC 2
52 6E Test DMA page register
53 6D Test 8237 DMA controller 1
54 6C Test 8237 DMA controller 2
55 6B Test PIO port 61h
56 6A Test the keyboard controller
57 69 Test the CMOS clock/calendar IC
59 68 Test the CPU protected mode
5A 66 Test CMOS RAM battery
5B 65 Test CMOS RAM
5C 64 Verify CMOS RAM checksum
5D 63 Test parallel port configuration
5E 62 Test serial port configuration
5F 61 Test memory configuration below 640KB
60 60 Test memory configuration above 1MB
61 5F Detect and test math coprocessor
62 5E Test configuration of game port adapter
62 5D Test key lock switch
63 5D Test hard drive configuration
64 5C Configure floppy drives
66 5B Test option ROM's
- - Call interrupt 19 boot loader

Return to Top

Olivetti M20 BIOS Post Codes:
Triangle Test CPU registers and instructions
Triangle Test system RAM
4 vertical lines Test CPU call and trap instructions
Diamond Initialize screen and printer drivers
EC0 8255 parallel interface IC test failed
EC1 6845 CRT controller IC test failed
EC2 1797 floppy disk controller chip failed
EC3 8253 timer IC failed
EC4 8251 keyboard interface failed
EC5 8251 keyboard test failed
EC6 8259 PIC IC test failed
EK0 Keyboard did not respond
Ek1 Keyboard responds, but self test failed
ED1 Disk drive 1 test failed
ED0 Disk drive 0 test failed
E10 Non-vectored interrupt error
E11 Vectored interrupt error

Return to Top

Olivetti M24/AT&T BIOS Post Codes:
40 CPU flags and register test failed
41 BIOS ROM checksum test failed
42 Disable 8253 timer channel 1
43 8237 DMA controller test failed
44 8259 PIC test failed
45 Install the real interrupt vectors
48 Send beep and initialize all basic hardware

Return to Top

Olivetti PS/2 BIOS Post Codes:
01 Test CPU
02 Check CMOS shutdown byte
03 Initialize the PIC
04 Test refresh
05 Test CMOS/RTC periodic interrupt
06 Test timer ratio
07 Test first 64KB of RAM
08 Test 8042 keyboard controller
09 Test NMI
0A Test 8254 PIT
0B Test port 94h
0C Test port 103h
0D Test port 102h
0E Test port 96h
0F Test port 107h
10 Blank the display
11 Check the keyboard
12 Test CMOS RAM battery
13 Verify CMOS RAM checksum
14 Verify extended CMOS RAM checksum
15 Initialize system board and adapter
16 Initialize and test RAM
17 Test protected mode registers
18 Test CMOS RAM shutdown byte
19 Test CMOS protected mode
1A Initialize video adapter ROM scan
1B Test BIOS ROM checksum
1C Test PIC #1
1D Test PIC #2
1E Initialize interrupt vectors
1F Test CMOS RAM
20 Test extended CMOS RAM
21 Test CMOS real-time clock
22 Test clock calendar
23 Dummy checkpoint
24 Test watchdog timer
25 Test 64KB to 640KB RAM
26 Configure lower 640KB RAM
27 Test extended memory
28 Initialize extended BIOS data segment and log POST error
29 Configure memory above 1MB
2A Dummy checkpoint
2B Test RAM parity
2C Test DMA page registers
2D Test DMA controller registers
2E Test DMA transfer-count register
2F Initialize DMA controller
30 Test PIO 61
31 Test the keyboard
32 Initialize keyboard typematic rate and delay
33 Test auxiliary device
34 Test advanced protected mode
35 Configure parallel ports
36 Configure 8250 serial ports
37 Test and configure math co-processor
38 Test and configure game-port adapter
39 Configure and initialize hard disk
3A Floppy-disk configuration
3B Initialize ROM drivers
3C Display total memory and hard drives
3D Final initialization
3E Detect and initialize parallel ports
3F Initialize hard drive and controller
40 Initialize math co-processor
42 Initialize adapter ROM scan
CC Unexpected processor excerption occurred
DD Save DDNIL status
EE NMI handler shutdown
FF Call interrupt 19 boot loader

NCR beep codes:

NCR PC6 (XT) BIOS Post Codes:
AA 8088 CPU failure
B1 2764 EPROM checksum failure
B2 8237 DMA controller failure
B3 8253 PIT failure
B4 RAM failure
B5 8259 PIC failure
B6 RAM parity failure
BB All tests passed, ready to boot

Return to Top

NCR AT BIOS Post Codes:
01 Test the CPU registers
02 Test system support I/O
03 Test BIOS ROM checksum
04 Test DMA page registers
05 Test timer channel 1
06 Test timer channel 2
07 Test RAM refresh logic
08 Test base 64KB
09 Test 8/16 bit bus conversion
0A Test interrupt controller 1
0B Test interrupt controller 2
0C Test I/O controller
0D Test CMOS RAM read/write operation
0E Test battery power
0F Test CMOS RAM checksum
10 Test CPU protected mode
11 Test video configuration
12 Test primary video controller
13 Test secondary video controller
20 Display results of tests to this point
21 Test DMA controller 1
22 Test DMA controller 2
23 Test system timer channel 0
24 Initialize interrupt controllers
25 Test interrupts
26 Test interrupts
30 Check base 640KB memory
31 Check extended memory size
32 Test higher 8 address lines
33 Test base memory
34 Test extended memory
40 Test keyboard
41 Test keyboard
42 Test keyboard
43 Test keyboard
44 Test A20 gate
50 Setup hardware interrupt vectors
51 Enable interrupt timer channel 0
52 Check BIOS ROM
60 Test floppy disk controller and drive
61 Test hard disk controller
62 Initialize floppy drives
63 Initialize hard drives
70 Test real time clock
71 Set time of day in RTC
72 Check parallel interface ports
73 Check serial interface ports
74 Check for any option ROM's
75 Check math coprocessor
76 Enable keyboard and RTC interrupts
F0 System not configured properly or hardware defect
F1 Scan and execute any option ROM's
F2 Call interrupt 19 boot loader

Return to Top

NCR PC916 BIOS Post Codes:
01 Test CPU registers
03 Test BIOS ROM checksum
04 Test DMA page registers
05 Test timer channel 1
06 Test timer channel 2
0C Test 8042 keyboard controller
14 Test disabling speed stretch at port 69h
15 Start refresh timer 1
16 Enable speed stretch at port 69h
17 Clear write protect bit
1B Test 64KB shadow RAM
18 Write and test interrupt descriptor table
19 Verify RAM
02 Verify port 61h
07 Test refresh logic
08 Test base 64KB RAM
09 Test 8/16 bit bus conversion logic
0A Test interrupt mask register A
0B Test interrupt mask register B
1A Check 8042 keyboard controller
0D Test CMOS RAM shutdown byte
0E Test CMOS RAM battery power
0F Test CMOS RAM checksum
10 Test CPU protected mode
11 Test video configuration
12 Initialize and test primary video controller
13 Primary video error
20 Display results of tests to this point
21 Test DMA controller 1
22 Test DMA controller 2
23 Test timer 1 counter 0 840nS clock timer
27 Test timer 2 counter 0 for NMI
28 Test timer 2 counter
24 Initialize both interrupt controllers
25 Check for unexpected interrupts
26 Wait for interrupt
30 Check base 640KB memory
31 Check extended memory size
32 Test higher 8 address lines
33 Test base memory
34 Test extended memory up to 256MB
35 Test RAM in segment E000h
40 Test keyboard enable/disable
41 Test keyboard reset command
42 Test keyboard
43 Test keyboard
F4 Display speed setting
45 Initialize the mouse and enable IRQ 1
44 Test address overrun capability
50 Set up hardware interrupt vectors
51 Enable IRQ 0 interval interrupt from timer 0
60 Test for floppy and hard disk controllers and drives
61 Test disk controller
62 Initialize floppy drives
63 Initialize hard drives
74 Check and execute option ROM's from C8000h to DFFFFh
70 Test RTC
71 Set interval timer
72 Configure and test parallel interface
73 Configure and test serial interface
75 Test math coprocessor if installed
76 Enable keyboard and RTC
F0 Display and logged errors
F6 Test base memory
F3 Got to setup if F1 was pressed
F4 Display speed setting
F5 Initialize counter 2 for speed testing
F1 Test system code at E0000h and copy video ROM to shadow memory
F2 Call interrupt 19 boot loader
F6 Test base memory
F7 Test extended memory

HP Vectra Beep Codes:

01 LED test
02 Processor test
03 System (BIOS) ROM test
04 RAM refresh timer test
05 Interrupt RAM test
06 Shadow the system ROM BIOS
07 CMOS RAM test
08 Internal cache memory test
09 Initialize the video card
10 Test external cache
11 Shadow option ROM's
12 Memory subsystem test
13 Initialize EISA/ISA hardware
14 8042 keyboard controller self test
15 Timer 0 / Timer 2 test
16 DMA subsystem test
17 Interrupt controller test
18 RAM address line independence test
19 Size extended memory
20 Real mode memory test (first 640K)
21 Shadow RAM test
22 Protected mode RAM test (extended RAM)
23 Real time clock test
24 Keyboard test
25 Mouse test
26 Hard disk test
27 LAN test
28 Flexible disk controller subsystem test
29 Internal numeric coprocessor test
30 Weitek coprocessor test
31 Clock speed switching test
32 Serial port test
33 Parallel port test

HP Vectra ES BIOS Post Codes:

000F 80286 CPU is bad
0010 Bad checksum on ROM 0
0011 Bad checksum on ROM 1
011X One of the RTC registers is bad; Register = x(0-D)
0120 RTC failed to tick
0240 CMOS/RTC has lost power
0241 Invalid checksum, IBM CMOS area
0280 Invalid checksum, HP CMOS area
02XY One of the CMOS registers is bad; Register = XY - 40
0301 8042 failed to accept the reset command
0302 8042 failed to respond to the reset command
0303 8042 failed to reset
0311 8042 failed to accept the "WRITE CMD BYTE" command
0312 8042 failed to accept the data of the above command
0321 8042 failed to accept scancode from port 68
0322 8042 failed to respond to the above scancode
0323 8042 responded incorrectly to the above scancode
0331 8042 failed to accept command from port 6A
0332 8042 failed to generate SVC on port 67
0333 8042 generated HPINT type on port 65
0334 8042 failed the R/W register on port 69
0335 8042 failed to generate HPINT on IRQ 15
0336 8042 failed to generate HPINT on IRQ 12
0337 8042 failed to generate HPINT on IRQ 11
0338 8042 failed to generate HPINT on IRQ 10
0339 8042 failed to generate HPINT on IRQ 7
033A 8042 failed to generate HPINT on IRQ 5
033B 8042 failed to generate HPINT on IRQ 4
033C 8042 failed to generate HPINT on IRQ 3
0341 8042 failed keyboard interface test command
0342 8042didn't respond to interface command
0343 Keyboard clock line stuck low
0344 Keyboard clock line stuck high
0345 Keyboard data line stuck low
0346 Keyboard data line stuck high
0350 No ACK from keyboard self test command
0351 Bad ACK from keyboard self test command
0352 Keyboard is dead or not connected
0353 No result from keyboard self test command
0354 Keyboard self test failed
0401 8042 failed to enable gate A-20
0503 Serial port dead or non existent
0505 Serial port fails port register tests
0543 Parallel port dead or non-existent
06XX Stuck key; XX=scancode of key
0700 Failed to switch to slow mode
0701 Failed to switch to dynamic mode
0702 Timer (channel 0) failed to interrupt
0703 Memory cycles too slow in slow mode
0704 Memory cycles too fast in slow mode
0705 I/O cycles too slow in slow mode
0706 I/O cycles too fast in slow mode
0707 Memory cycles too slow in dynamic mode
0708 Memory cycles too fast in dynamic mode
0709 I/O cycles too slow in dynamic mode
070A I/O cycles too fast in dynamic mode
110X One of the timer channels failed to register test / X(0-2)=channel that failed
1200 Memory refresh signal stuck high
1201 Memory refresh signal stuck low
211X DMA 1 failed R/W test at register x (0-7)
212X DMA 2 failed R/W test at register x (0-7)
221X Bad DMA page register; X=register 0-7
300X HP-HIL controller failed self test; X=data
X = xx1 = >read/write fail with data = 0DA5h
X = xx1x = >read/write fail with data = 0DA5h
X = x1xx = >read/write fail with data = 0DA5h
X = 1xxx = >read/write fail with data = 0DA5h
3010 HP-HIL device test failed
4XYZ Lower 640K failed R/W test;
X=0,2,4,6 Y>0=Bad U23 Z>0=Bad U13
X=1,3,5,7 Y>0=Bad U43 Z>0=Bad U33
X=8 Y>0=Bad U22 Z>0=Bad U12
X=9 Y>0=Bad U42 Z>0=Bad U32
5XYZ Lower 640K failed marching ones test
X = bbbx = > bbb (0-7) is # of 128K bank
bbb0 = > Indicate even byte bad
bbb1 = > Indicate odd byte bad
YZ = bbbb bbbb = > Bits for which b = 1 are bad
61XY RAM address line XY stuck
Some address lines to RAM are stuck to 0 or 1
XY = 00bb bbbb = > RAM address line bbbbbb is stuck
XY = 01bb bbbb = > Multiple address lines are stuck (bbbbbb is the first bad one)
620X Lower 640K parity error; Bank X
X = Address in 64K bank where parity error occurred
if X = 0 to y, U21 and/or U31 is/are bad
if X = 8 to 9, U11 and/ore U41 is/are bad
63XY Parity error above 1MB; Bank XY
Parity error has occurred during RAM test above the first MB
XY = Address in 64K bank where parity occurred
6400 Parity generator failed to detect error
71XY Master 8259 failed R/W; bits XY
XY = bbbb bbbb + > bits in which b = 1 is bad
72XY Slave 8259 failed R/W; bits XY
XY = bbbb bbbb = > bits in which b = 1 is bad
7400 Master 8259 failed interrupt
7500 Slave 8259 failed interrupt
9XYZ Floppy drive controller error
X=drive #
Y=0=1st level error
Z=0 Unsuccessful input from FD
Z=1 Unsuccessful output to FDC
Z=2 Error while executing seek
Z=3 Error during recalibrate
Z=4 Error verifying RAM buffer
Z=5 Error while resetting FDC
Z=6 Wrong drive identified
Z=7 Wrong media identified
Z=8 No interrupt from FDC
Z=9 Failed to detect track 0
Z=A Failed to detect index pulse
Y>1=Higher level error
Y=1=Read sector error, side 0
Y=2=Read sector error, side 1
Y=3=Write sector error, side 0
Y=4=Write sector error, side 1
Y=5=Format sector error, side 0
Y=6=Format sector error, side 1
Y=7=Read ID error, side 0
Y=8=Read ID error, side 1
Z=1=No ID address mark
Z=2=No data address mark
Z=3=Media is write protected
Z=4=Sector # wrong
Z=5=Cylinder # wrong
Z=6=Bad cylinder
Z=7=DMA overrun
Z=8=ID CRC error
Z=9=Data CRC error
Z=A=End of cylinder
Z=B=Unrecognizable error
A001 No 80287 detected
A002 80287 failed stack register R/W test
A00C No zero-divide interrupt from 80287
CXYZ R/W error on extended RAM in XY bank
Read/Write test failure on extended RAM
X = 0 = > Even byte is bad
X = 1 = > Odd byte is bad
XY = Address in 64K bank where RAM failed
CFFF Extended RAM marching ones failed
Marching on test failure on extended RAM
X = 0 = > Even byte bad
X = 1 = > Odd byte bad
XA = Address in 64K bank where RAM failed

HP Vectra QS & RS BIOS Post Codes:

000F 386 CPU bad
0010 Bad checksum on ROM 0
0011 Bad checksum on ROM 1
011X RTC register is bad
0120 RTC failed to tick
0240 CMOS/RTC lost power
0241 Invalid checksum, IBM CMOS area
0280 Invalid checksum, HP CMOS area
02XY Bad CMOS register, at XY-40
0301 8042 failed to accept reset command
0302 8042 failed to respond to reset
0303 8042 failed on reset
0311 8042 didn't accept "WRITE CMD BYTE"
0312 8042 didn't accept data
0321 8042 failed to accept scancode, port 68
0322 8042 failed to respond to the above scancode
0323 8042 responded incorrectly to the above scancode
0331 8042 failed to accept command from port 6A
0332 8042 failed to generate SVC on port 67
0333 8042 generated HPINT type on port 65
0334 8042 failed the R/W register on port 69
0335 8042 failed to generate HPINT on IRQ 15
0336 8042 failed to generate HPINT on IRQ 12
0337 8042 failed to generate HPINT on IRQ 11
0338 8042 failed to generate HPINT on IRQ 10
0339 8042 failed to generate HPINT on IRQ 7
033A 8042 failed to generate HPINT on IRQ 5
033B 8042 failed to generate HPINT on IRQ 4
033C 8042 failed to generate HPINT on IRQ 3
0341 8042 failed keyboard interface test command
0342 8042didn't respond to interface command
0343 Keyboard clock line stuck low
0344 Keyboard clock line stuck high
0345 Keyboard data line stuck low
0346 Keyboard data line stuck high
0350 No ACK from keyboard self test command
0351 Bad ACK from keyboard self test command
0352 Keyboard is dead or not connected
0353 No result from keyboard self test command
0354 Keyboard self test failed
0401 8042 failed to enable gate A-20
0503 Serial port dead or non-existent
0505 Serial port fails port register tests
06XX Stuck key; XX=scancode of key
0700 Failed to switch to slow speed
0701 Failed to switch to fast speed
0702 Timer failed to interrupt
0703 CPU clock too slow in slow speed
0704 CPU clock too fast in slow speed
0707 CPU clock too slow in fast speed
0708 CPU clock too fast in fast speed
0709 Failed to switch bus clock to ATCLK
110X Timer X (0-2) failed to register test
1200 Memory refresh signal stuck high
1201 Memory refresh signal stuck low
211X DMA 1 failed R/W test at register x (0-7)
212X DMA 2 failed R/W test at register x (0-7)
221X Bad DMA page register; X=register 0-7
300X HP-HIL controller failed self test; X=data
X = xxx1 = > read/write fail with data = 0DA5Ah
X = xx1x = > read/write fail with data = 0DA5Ah
X = x1xx = > read/write fail with data = 0DA5Ah
X = 1xxx = > read/write fail with data = 0DA5Ah
3010 HP-HIL device test failed
4XYZ Lower 640K failed R/W test;
X=0,2,4,6 Y>0=Bad U23 Z>0=Bad U13
X=1,3,5,7 Y>0=Bad U43 Z>0=Bad U33
X=8 Y>0=Bad U22 Z>0=Bad U12
X=9 Y>0=Bad U42 Z>0=Bad U32
5XYZ Lower 640K failed marching ones test
RAM in lower 640K failed read/write test
X = bbcc = > bb is # 64K of 32 bit word bank
cc = 00 = > byte 0 is bad
cc = 01 = > byte 1 is bad
cc = 02 = > byte 2 is bad
cc = 03 = > byte 3 is bad
YZ = bbbb bbbb = > bits for which b = 1 are bad
61XY RAM address line XY stuck
Some address lines to RAM are stuck to 0 or 1
XY = 00bb bbbb = > RAM address line bbbbbb is stuck
XY = 01bb bbbb = > Multiple address lines are stuck bbbbbb is the first bad one
620X Lower 640K parity error; Bank X
X = Address in 64K bank where parity occurred
63XY Parity error above 1MB; Bank XY
XY = Address in 64K bank where parity occurred
6500 Shadow RAM bad at BIOS segment
6510 Shadow RAM bad at HP EGA segment
71XY Master 8259 failed R/W; bits XY
XY = bbbb bbbb = > bits which b = 1 is bad
72XY Slave 8259 failed R/W; bits XY
XY = bbbb bbbb = > bits which b = 1 is bad
7400 Master 8259 failed interrupt
7500 Slave 8259 failed interrupt
9XYZ Floppy drive controller error
X=drive #
Y=0=1st level error
Z=0 Unsuccessful input from FD
Z=1 Unsuccessful output to FDC
Z=2 Error while executing seek
Z=3 Error during recalibrate
Z=4 Error verifying RAM buffer
Z=5 Error while resetting FDC
Z=6 Wrong drive identified
Z=7 Wrong media identified
Z=8 No interrupt from FDC
Z=9 Failed to detect track 0
Z=A Failed to detect index pulse
Y>1=Higher level error
Y=1=Read sector error, side 0
Y=2=Read sector error, side 1
Y=3=Write sector error, side 0
Y=4=Write sector error, side 1
Y=5=Format sector error, side 0
Y=6=Format sector error, side 1
Y=7=Read ID error, side 0
Y=8=Read ID error, side 1
Z=1=No ID address mark
Z=2=No data address mark
Z=3=Media is write protected
Z=4=Sector # wrong
Z=5=Cylinder # wrong
Z=6=Bad cylinder
Z=7=DMA overrun
Z=8=ID CRC error
Z=9=Data CRC error
Z=A=End of cylinder
Z=B=Unrecognizable error
A001 No 80287 detected
A002 80287 failed stack register R/W test
A00C No zero-divide interrupt from 80287
AF00 Weitek coprocessor didn't enter protected mode
AF01 Weitek coprocessor nor present
AF02 Weitek coprocessor fails register test
AF05 Weitek coprocessor fails addition test
AF06 Weitek coprocessor fails interrupt test
AF0C Weitek coprocessor fails interrupt test
CXYZ R/W error on extended RAM in XY bank
X = 0 = > Even byte bad
X = 1 = > Odd byte bad
XY = Address in 64K bank where RAM failed
CFFF No extended RAM found
EXYZ Extended RAM marching ones failure at XYZ
X = 0 = > Byte 0 is bad
X = 1 = > Byte 1 is bad
X = 2 = > Byte 2 is bad
X = 3 = > Byte 3 is bad

HP Pavilion Series 3100 & 8000 BIOS Post Codes:

02 Verify real mode
03 Disable NMI
04 Get processor type
06 Initialize system hardware
08 Initialize chipset with POST values
09 Set IN-POST flags
0A Initialize CPU registers
0B Enable CPU registers
0C Initialize cache to POST values
0E Initialize I/O component
0F Initialize local IDE bus
10 Initialize power management
11 Load alternate registers
12 Restore CPU control word during warm boot
13 Initialize PCI bus mastering devices
14 Initialize keyboard controller
16 BIOS ROM checksum
17 Initialize cache before memory size
18 Initialize 8254 timer
1A Initialize DMA controller
1C Reset PIC
20 Test DRAM refresh
22 Test 8742 keyboard controller
24 Set ES segment register to 4GB
26 Enable A-20 line
28 Autosize DRAM
29 Initialize POST memory manager
2A Clear 512K base RAM
2C RAM address line failure
2E RAM data failure, low byte
2F Enable cache before BIOS shadow
30 RAM data failure, high byte
32 Test CPU, BUS clock frequency
33 Initialize POST dispatch manager
34 Test CMOS RAM
35 Initialize alternate chipset registers
36 Warm start shut-down
37 Reinitialize chipset (MB only)
38 Shadow system BIOS ROM
39 Reinitialize cache (MB only)
3A Autosize cache
3C Configure advanced chipset registers
3D Load alternate registers new CMOS values
40 Set initial CPU speed
42 Initialize interrupts
44 Initialize BIOS interrupts
45 POST device initialization
46 Check ROM copyright notice
47 Initialize manager for PCI option ROM's
48 Check video config against CMOS
49 Initialize manager for PCI option ROM's
4A Initialize all video adapters
4B Display quiet boot screen
4C Shadow video BIOS
4E Display BIOS copyright notice
50 Display CPU type & speed
51 Initialize
52 Test keyboard
54 Set key click if enabled
56 Enable keyboard
58 Test for unexpected interrupts
59 Initialize POST display service
5A Display "Press F2 to Enter Setup"
5B Disable CPU cache
5C Test RAM, 512-640K
60 Test extended memory
62 Test extended memory address lines
64 Jump to user patch 1
66 Configure advanced cache registers
67 Initialize multi-processor APIC
68 Enable external & processor caches
69 Set up SMM area
6A Display external L2 cache size
6C Display shadow area message
6E Display high address for UMB recovery
70 Display error message
72 Check for configuration errors
74 Test real time clock
76 Check for keyboard errors
7A Test for key lock on
7C Set up hardware interrupt vectors
7E Initialize coprocessor, if present
80 Disable onboard super I/O ports
81 Late POST device initialization
82 Detect & install external RS-232 ports
83 Configure non-MDC IDE controllers
84 Detect & install external parallel ports
85 Initialize PnP ISA devices
86 Reinitialize onboard I/O ports
87 Configure motherboard configurable devices
88 Initialize BIOS data area
89 Enable NMI's
8A Initialize extended BIOS data area
8B Test & initialize PS/2 mouse
8C Initialize floppy controller
8F Determine number of ATA drives
90 Initialize hard disk controllers
91 Initialize local BUS HD controllers
92 Jump to user patch 2
93 Build MPTABLE for multiprocessor boards
94 Disable A-20 line
95 Install CD-ROM for boot
96 Clear huge ES segment register
97 Fix up multiprocessor table
98 Search for options ROM's
99 Check for smart drive
9A Shadow ROM option
9C Set up power management
9E Enable hardware interrupts
9F Determine number of ATA & SCSI drives
A0 Set time of day
A2 Check key lock
A4 Initialize typematic rate
A8 Erase F2 prompt
AA Scan for F2 keystroke
AC Enter SETUP
AE Clear IN-POST flag
B0 Check for errors
B2 POST done, prepare for boot
B4 One short beep before boot
B5 Terminate quiet boot
B6 Check password (optional)
B8 Clear global descriptor table
B9 Clean up all graphics
BA Initialize DMI parameters
BB Initialize PnP option ROM's
BC Clear parity checkers
BD Display multi boot menu
BE Clear screen optional
BF Check virus and backup reminders
C0 Try to boot with Int 19
C1 Initialize POST error manager
C2 Initialize error logging
C3 Initialize error display function
C4 Initialize system error handler
E0 Initialize the chipset
E1 Initialize the bridge
E2 Initialize the processor
E3 Initialize system timer
E4 Initialize system I/O
E5 Check force recovery boot
E6 Checksum BIOS ROM
E7 Got to BIOS
E8 Set huge segment
E9 Initialize multiprocessor
EA Initialize OEM special code
EB Initialize PIC & DMA
EC Initialize memory type
ED Initialize memory type
EE Shadow boot block
EF System memory test
F0 Initialize interrupt vectors
F1 Initialize runtime clock
F2 Initialize video
F3 Initialize beeper
F4 Initialize BOOT
F5 Clear huge segment
F6 Boot to mini-DOS
F7 Boot to full DOS

DELL:

Dell BIOS Beep Codes:
Beep Codes Possible Causes Corrective Action
1 - 2 No video card detected Reseat the video card
1 - 2 - 2 - 3 BIOS ROM checksum error
1 - 3 - 1 - 1 DRAM refresh error Reseat the memory modules
1 - 3 - 1 - 3 8742 Keyboard Controller error Reseat the keyboard connector
1 - 3 - 3 - 1 Memory defective or not present Reseat the memory modules
1 - 3 - 4 - 1 RAM failure on line xxx Reseat the memory modules
1 - 3 - 4 - 3 RAM failure on data bits xxx of low byte on memory bus Reseat the memory modules
1 - 4 - 1 - 1 RAM failure on data bits xxx of high byte on memory bus Reseat the memory modules

Dell BIOS System Messages:
Message Possible Cause Corrective Action
nnnn Cache RAM Passed nnnn KB of system cache RAM has been successfully tested
nnnn Extended RAM Passed nnnn KB of extended RAM has been tested
nnnn Shadow RAM Passed nnnn KB of shadow RAM has been successfully tested
nnnn System RAM Passed nnnn KB of system RAM has been successfully tested
CD-ROM drive Identified The systems automatic drive type detection feature has identified the CD-ROM drive
Diskette drive A error; Diskette drive B Error Drive A or B is present but has failed the BIOS POST Ensure that the drive is installed correctly in the chassis and detected correctly in the system setup
Entering Setup The system is starting the system setup program
Extended RAM Failed at offset: nnnn Extended memory is not working correctly or is not configured correctly at offset: nnnn IF you receive this message after making changes in the system setup program, enter the program and restore the original value(s)
Failing bits: nnnn nnnn is a map of the bits at RAM address that failed the memory test. Each 1 in the map indicates a failed bit If you receive this message after making changes in the system setup program, enter the program and restore the original value(s)
Fixed Disk n Failure; Fixed Disk Controller Failure The hard drive specified by n is not working or not configured correctly Ensure that the drive is installed correctly in the chassis and defined coracle in the system setup program
Fixed Disk n Identified The system's automatic drive type detection feature has identified the hard disk drive(s)
Incorrect Drive x type - Run Setup Diskette drive x is not correctly identified in the system setup program Ensure that the drive is defined correctly in the system setup program
Invalid NVRAM media type The system is having a problem accessing NVRAM (CMOS) Set the configuration jumper to Maintenance mode and restart the system to return all settings to their defaults
Invalid system configuration data The system configuration information is the system setup program is incorrect, or the battery charge may be low Enter the system setup program and verify the system configuration, then restart the system
Keyboard controller error The keyboard controller failed it's test If you receive this message after making changes in the system setup program, enter the program and restore the original value(s)
Keyboard error The keyboard is not working correctly The keyboard or system board may need to be replaced
Keyboard error nn The BIOS has detected a stuck key represented by scan code nn Make sure nothing is resting on the keyboard. If a key appears to be stuck, carefully pry it up. if the problem persists, you may need to replace the keyboard
Mouse initialized The system's mouse has been found and initialized
Operating system not found The operating system cannot be located on drive A or drive C Enter the system setup program and confirm that drive A or drive C is properly identified
Parity check 1 nnnn A parity error has been detected on the system bus. The BIOS attempts to locate the address and display it nnnn. If it cannot locate the address, it displays ???? instead If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
Parity check 2 nnnn A parity error has been detected on the I/O bus. The BIOS attempts to locate the address and display it nnnn. If it cannot locate the address, it displays ???? instead If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
Press <F1> to resume, <F2> to Setup This message is displayed after a recoverable error message Press <F1> to start the boot routine or <F2> to enter the system setup program and change any settings
Press <Del> to enter SETUP Optional message displayed during POST Id desired, press <Del> to enter the system setup program
Previous boot incomplete - Default configuration used After a unsuccessful boot, POST loads default values There may be incorrect values or incorrect settings in the system setup program. Run the system setup program and attempt to restore the incorrect settings. If the message reappears, set the configuration jumper to Maintenance mode and restart the system to return all settings to their defaults
Real time clock error The RTC has failed the BIOS test If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
Resource allocation conflict on motherboard The system cannot configure all system board devices without a resource conflict Run the system setup program and try to resolve any obvious resource conflicts. If the message reappears, set the configuration jumper to Maintenance mode and restart the system to return all settings to their defaults
Shadow RAM failed at offset: nnnn Shadow RAM has failed at offset nnnn in the 64KB block in which the error was detected If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
System battery is dead - Replace and run SETUP The CMOS clock battery indicator shows the battery is dead Replace the battery and run the system setup program to reconfigure the system
System BIOS shadowed The system BIOS has been copied to shadow RAM
System cache error - cache disabled RAM cache failed the BIOS test. The BIOS has disabled the cache If you receive this message after making changes in the system setup program, enter the program and restore the original settings
System CMOS checksum bad - run SETUP System CMOS has been corrupted or modified incorrectly, perhaps by an application program that changes data stored in CMOS Run the system setup program and reconfigure the system by either reverting to the default values or by making your own selections
System RAM failed at offset: nnnn System RAM failed at offset nnnn in the 64KB block in which the error was detected If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
System timer error The timer test failed If you receive this message after making changes in the setup program, enter the program and restore the original values(s)
UMB Upper limit segment address: nnnn Displays the address nnnn of the upper limit of the UMB, indicating released segments of the BIOS which may be reclaimed by a virtual memory manager
Video BIOS shadowed The video BIOS has been successfully copied to shadow RAM

Dell BIOS Post Codes:
01 CPU register test in progress
02 CMOS read/write test failed
03 BIOS ROM checksum bad
04 8254 programmable interrupt controller failed
05 DMA controller initialization failed
06 DMA page-register test failed
08 RAM refresh verification failed
09 Starting first-64K RAM test
0A First-64KB RAM IC or data line bad
0B First-64KB RAM odd/even logic bad
0C First-64KB address line bad
0D First-64KB parity error
10 Bit 0 bad in first 64KB
11 Bit 1 bad in first 64KB
12 Bit 2 bad in first 64KB
13 Bit 3 bad in first 64KB
14 Bit 4 bad in first 64KB
15 Bit 5 bad in first 64KB
16 Bit 6 bad in first 64KB
17 Bit 7 bad in first 64KB
18 Bit 8 bad in first 64KB
19 Bit 9 bad in first 64KB
1A Bit 10 bad in first 64KB
1B Bit 11 bad in first 64KB
1C Bit 12 bad in first 64KB
1D Bit 13 bad in first 64KB
1E Bit 14 bad in first 64KB
1F Bit 15 bad in first 64KB
20 Slave DMA register bad
21 Master DMA register bad
22 Master interrupt-mask register bad
23 Slave interrupt-mask register bad
25 Loading interrupt vectors
27 Keyboard-controller test failed
28 CMOS RAM battery bad
29 CMOS configuration validation in progress
2B Video-memory test failed
2C Video initialization failure
2D Video-retrace failure
2E Searching for a video ROM
30 Switching to video ROM
31 Monochrome operation OK
32 Color (CGA) operation OK
33 Color operation OK
34 Timer-tick interrupt in progress (or bad)
35 CMOS shutdown test in progress (or bad)
36 Gate A20 bad
37 Unexpected interrupt in protected mode
38 RAM test in progress or high address line is bad
3A Interval timer channel 2 bad
3B Time-of-day test bad
3C Serial-port test bad
3D Parallel -port test bad
3E Math co-processor test bad
3F Cache-memory test bad

DTK motherboards:

DTK BIOS Post Codes:
01 Testing the CPU
03 Initialize the 8259 interrupt controller
05 Initialize the video board - MCA & CGA
0D Initialize the 8237 DMA controller
0E Initialize the DMA 74612 page registers
12 Test the 8042 keyboard controller
16 Test the DMA 7237 controller and 8254 programmable interrupt timer
22 Testing DRAM refresh circuitry
25 Base 64KB memory test
30 Set up system stack
33 Read-system configuration through 8042 keyboard controller
37 Test keyboard clock and data line
40 Determine video type
44 Locate and test, if present, MDA and CGA video
48 Initialize video 80 x 25 mode
4D Display DTK BIOS copyright message
4F Check serial and parallel ports
50 Check floppy disk controller
55 Check shadow RAM
58 Display total memoryand switch to real mode
5A Successful switch back to real mode
60 Check hard disk drive controller
62 Initialize floppy drive
65 Initialize hard drive
67 Initialize the floppy disk drive and the hard disk drive
6A Disable gate A20 and test math coprocessor
70 Set system date and time RTC-146918
77 Call interrupt 19 boot loader

AT&T

AT&T BIOS Post Codes:
01 CPU test
02 System I/O port test
03 ROM checksum test
05 DMA page register test
06 Timer 1 test
07 Timer 2 test
08 RAM refresh test
09 8/19 bit bus conversion check
0A Interrupt controller 1 test
0B Interrupt controller 2 test
0C Keyboard controller test
0D CMOS RAM/RTC test
0E Battery power test
0F CMOS RAM checksum test
10 CPU protected mode
11 Display configuration test
12 Display controller test
13 Primary display error
14 Extended CMOS test
15 AT bus reset
16 Initialize chipset registers
17 Check for extension ROM's
18 Internal memory address test
19 Remap memory
1A Memory interleave mode test
1B Remap shadow memory
1C Setup MRAM
1D Expanded memory test
1E AT memory error
1F Internal memory error
20 Minimum POST tests complete
21 DMA controller 1 test
22 DMA controller 2 test
23 Timer 0 test
24 Initialize internal controllers
25 Unexpected interrupt
26 Expected interrupt
30 Switch to protected mode
31 Size AT bus memory or size external memory
32 Address lines A16 to A23 test
33 Internal memory test or conventional memory test
34 AT bus memory test or external memory test
38 Shadow ROM BIOS to RAM
39 Shadow extension BIOS to RAM
40 Enable/disable keyboard
41 Keyboard clock and data test
42 Keyboard reset
43 Keyboard controller test
44 A20 gate test
50 Initialize interrupt table
51 Enable timer interrupt
60 Floppy controller/drive test
61 Hard disk controller test
62 Initialize floppy drives
63 Initialize hard drives
70 Real time clock test
71 Set real time clock
72 Test parallel interfaces
73 Test serial interfaces
74 Check external ROM's
75 Numeric coprocessor test
76 Enable keyboard and RTC interrupts (IRQ 9)
F0 Display system startup message
F1 Check for ROM at E000h
F2 Boot from floppy or hard disk
F3 Run setup program
F4 Run password program
FC DRAM type detection
FD CPU register test

AT&T BIOS Post Codes v3.0:
01 CPU test 1: verify CPU status bits
02 Powerup check - Initialize motherboard and chipset with default values; Check 8042 keyboard controller buffer
03 Clear 8042 keyboard controller - send command AA, fail if status is not 2 output buffer full
04 Reset 8042 keyboard controller
05 Get8042 keyboard controller manufacturing status
06 Initialize motherboard chipset; disable color/mono video; disable 8237 DMA controller; reset 80x87 coprocessor; initialize 8255 timer 1; clear DMA/page registers/CMOS RAM shutdown byte
07 CPU test 2; read/write/verify CPU registers SS, SP, BP, with FF and 00
08 Initialize CMOS RAM/RTC
09 Checksum 32K of BIOS ROM
0A Initialize video interface; initialize 6845 controller
0B Test 8254 programmable interrupt timer channel 0
0C Test 8254 programmable interrupt timer channel 1
0D Test 8254 programmable interrupt timer channel 2
0E Test CMOS RAM shutdown byte
0F Test extended CMOS RAM, if present
10 Test 8237 DMA controller channel 0
11 Test 8237 DMA controller channel 1
12 Test 8237 DMA controller page registers
13 Test 8741 keyboard controller interface
14 Test memory refresh toggle
15 Test first 64K of base memory
16 Set up interrupt tables in low memory
17 Set up video I/O operations
18 (1 beep) Test MDA/CGA video memory unless EGA/VGA adapter is found
19 Test 8259 programmable interrupt timer channel 1
1A Test 8259 programmable interrupt timer channel 0
1B Test CMOS RAM battery level
1C Test CMOS RAM checksum
1D Set system memory size parameters
1E Size base memory 64K at a time
1F Test base memory found from 64K to 640K
20 Test stuck bit in 8259 programmable interrupt controller
21 Test for stuck NMI bits
22 Test 8259 programmable interrupt controller functionality
23 Test protected mode
24 Size extended memory above 1MB
25 Test all base and extended memory found, except the first 64K
26 Test protected mode exceptions
27 Initialize shadow RAM and move system BIOS and/or video BIOS into it if enabled by CMOS RAM setup
28 Detect and initialize Intel 8242/8248 chip
29 Reserved
2A Detect and initialize keyboard
2B Detect and initialize floppy drive
2C Detect and initialize serial ports
2D Detect and initialize parallel ports
2E Detect and initialize hard drive
2F Detect and initialize coprocessor
30 Reserved
31 Detect and initialize adapter ROM's
BD Initialize Orvonton cache controller, if present
CA Initialize 386 Micronics cache, if present
CC Shutdown NMI handler
EE Test for unexpected processor exception
FF Interrupt 19 boot loader

AT&T BIOS Post Codes v3.00 - 3.03 8/26/87 286 N3.03 Extensions:
01 Processor test #1
02 Determine type of POST test
03 Clear 8042 keyboard controller interface
04 Reset 8042 keyboard controller interface
05 Get 8042 keyboard controller manufacturing status
06 Initialize LSI onboard chips
07 Processor test #2
08 Initialize CMOS chip
09 EPROM checksum for 32KB
0A Initialize video interface
0B Test 8254 programmable interrupt timer channel 0
0C Test 8254 programmable interrupt timer channel 1
0D Test 8254 programmable interrupt timer channel 2
0E Test CMOS date and timer
0F Test CMOS shutdown byte
10 Test DMA channel 0
11 Test DMA channel 1
12 Test DMA page registers
13 Test 8741 keyboard controller
14 Test memory refresh toggle circuits
15 Test 1st 64KB of system memory
16 Setup interrupt vector table
17 Setup video I/O operations
18 Test video memory
19 Test 8259 programmable interrupt controller channel 1 mask bits
1A Test 8259 programmable interrupt controller channel 2 mask bits
1B Test CMOS battery level
1C Test CMOS checksum
1D Setup configuration byte for CMOS
1E Sizing system memory & compare with CMOS
1F Test found system memory
20 Test stuck 8259's interrupt bits
21 Test stuck NMI bits
22 Test 8259 programmable interrupt controller functionality
23 Test protected mode and A20 gate
24 Sizing extended memory above 1MB
25 Test found system/extended memory
26 Test exceptions in protected mode
27 Reserved
2A POST_KEYBOARD
2B POST_FLOPPY
2C POST_COMM
2D POST_PRN
2E POST_DISK
2F POST_MATH
30 POST_EXCEPTION
CC POST_NMI

AT&T BIOS Post Codes XT 8088/86 BIOS v3.1:
01 Processor test 1
02 Determine type of POST test
06 Initialize 8259 programmable interrupt controller and 8237 DMA controller chips
07 Processor test #2
09 EPROM checksum for 32KB
0A Initialize video controller 6845 registers
15 Test 1st 64K of system memory
16 Setup interrupt vector table in 1st 64K
17 Setup video I/O operations
18 Test video memory
19 Test 8259 programmable interrupt controller channel 1 mask bits
1A Test 8259 programmable interrupt controller channel 2 mask bits
1D Setup configuration byte from CMOS
1E Sizing system memory & compare with CMOS
1F Test found system memory
20 Test stuck 8259's interrupt bits
21 Test stuck NMI bits
22 Test 8259 interrupt functionality
2A Initialize keyboard
2B Initialize floppy controller and drive
2C Initialize COM ports
2D Initialize LPT ports
2F Initialize coprocessor
31 Initialize option ROM's
FF Interrupt 19 boot loader

ACER motherboards:

04 CPU verification; POST start
08 Shutdown condition 0; Shutdown byte 0
0C BIOS ROM checksum tested
10 CMOS ROM shutdown byte tested
14 DMA controller tested
18 System timer initialized
1C Memory refresh system tested
1E Memory type determined
20 Base 128K memory tested
24 8042 keyboard controller tested
28 CPU descriptor instruction tested
2C 8259 PIT tested
30 Temporary Interrupts located and initialized
34 BIOS Interrupt vectors and routines configured
38 CMOS RAM tested
3C Memory size determined
40 Shutdown condition 1
44 Video BIOS ROM initialized
45 RAM initialized and tested
46 Cache memory and controller initialized and tested
48 Memory tested
4C Shutdown condition 3
50 Shutdown condition 2
54 Shutdown condition 7
58 Shutdown condition 6
5C Keyboard and auxiliary I/O tested
60 BIOS Interrupt routines setup
64 RTC tested
68 Floppy drive and controller tested
6C Hard drive and controller tested
70 Parallel port tested
74 Serial port tested
78 Time of day setup
7C Optional ROM's searched for and started
80 Math coprocessor tested
84 Keyboard tested
88 System initialized
8C System initialized
90 Operating system boot process started
94 Shutdown condition 5
98 Shutdown condition A
9C Shutdown condition B

ALR Motherbaords:

01 CPU register test in progress
02 Real-time clock write/read failure
03 ROM BIOS checksum failure
04 Programmable internal timer failure (or no video card present)
05 DMA initialization failure
06 DMA page register write/read failure
08 RAM-refresh verification failure
09 1st 64KB RAM test in progress
0A 1st 64KB RAM chip or data line multi-bit failure
0B 1st 64KB RAM odd/even logic failure
0C Address line failure 1st 64KB RAM
0D Parity failure 1st 64KB RAM
10-1F bit 0-15 64KB RAM failure
20 Slave DMA-register failure
21 Master DMA-register failure
22 Master-interrupt mask-register failure
23 Slave-interrupt mask-register failure
25 Interrupt vector loading in progress
27 Keyboard-controller test failure
28 RTC power failure and checksum calculation in progress
29 Real-time clock-configuration validation in progress
2B Screen-memory test failure
2C Screen-initialization failure
2D Screen-retrace test failure
2E Search believed operational on screen believed running with video ROM
30 Monochrome display believed operable
32 Color display (40 column) believed operable
33 Color display (80 column) believed operable

ARCHE Legacy motherboards:

01 Disable the NMI and test CPU registers
02 Verify the BIOS ROM checksum (32KB at F8000h)
03 Initialize the keyboard controller and CMOS RAM communication
04 Disable the DMA and PIT; test the CMOS RAM interrupt
05 Reset the video controller
06 Test the 8254 programmable interrupt timer
07 Test delta count timer channel 2 (speaker)
08 Test delta count timer channel 1 (memory refresh)
09 Test delta count timer channel 0 (system timer)
0A Test parity circuit and turn on refresh
0B Enable parity check and test system timer
0C Test refresh trace link toggle
0D Test refresh timing synchronization
10 Disable cache and shadow memory; test the 64KB base memory
11 Perform 64KB memory read/write test
12 Initialize interrupt vector table in lower 1KB of RAM
14 Test CMOS RAM shutdown register...disable DMA and interrupt controllers
15 Test CMOS RAM battery and checksum
16 Test for floppy drive, based on CMOS setup...initialize monochrome video
17 Initialize CGA video
18 Clear the parity status (if any)
19 Test for EGA/VGA video BIOS at C0000h and pass control
1A Return from video ROM
1B Test primary video adapter...test video memory
1C Test secondary video adapter...test video memory
1D Compare CMOS settings to video adapter
1E Set video mode according to CMOS settings
20 Display CMOS RAM read/write errors and halt
21 Set cursor and call interrupt 10 to display status message
22 Display power on message; "386 BIOS"; check if CPU speed is 25Mhz or 33Mhz
23 Read new cursor position
24 Display AMI copyright message at the bottom of the screen
25 Test shadow RAM
F0 Shadow RAM test failed
30 Ready to enter protected mode
31 Enter protected mode (A20 gate) and enable timer interrupt (IRQ 0)
32 Get memory size above 1MB
33 Get memory size below 640KB
34 Test memory above 1MB
35 Test memory below 1MB
37 Clear memory below 1MB
38 Clear memory above 1MB
39 Use CMOS shutdown byte and return to real mode
3A Test 64KB read/write
3B Test RAM below 1MB and show the area being tested
3C Test RAM above 1MB and show the area being tested
3D RAM test complete OK
3E Ready to return to real mode
3F Back in real mode
40 Disable A20 gate
41 Check for AMI copyright message in ROM
42 Display the AMI copyright message, if found
43 Test cache memory; Clear <Esc> message
4E Process shutdown 1; Return to real mode
4F Restore interrupt vectors and data in BIOS RAM area
50 Test DMA controller
51 Initialize DMA controller
52 Test the DMA controller with patterns
54 Test DMA controller latches
55 Initialize and enable DMA controllers 1 and 2
56 Initialize 8259 programmable interrupt controllers
57 Test 8259 programmable interrupt controllers and setup interrupt mask registers
61 Check DDNIL status bit and display message
70 Perform keyboard (BAT) basic assurance test
71 Program keyboard to AT type
72 Disable keyboard and initialize keyboard circular buffer
73 Display message and initialize floppy controller and drive
74 Attempt to access the floppy drive
75 If the CMOS RAM is good, check and initialize the hard disk controller and drive
76 Attempt to access the hard disk drive
77 Shuffle and internal error codes
79 Check CMOS RAM battery and checksum...clear parity status
7A Compare size of base/extended memory to CMOS information
7B Unknown AMI function
7C Display AMI copyright
7D Set AT memory expansion bit
7E Verify the ROM contains and AMI copyright
7F Clear the <Del> message from the display...check if <Del> was pressed
80 Locate option ROM at C800h to DE00h and pass control to any found
81 Return from option ROM and initialize timer and data area
82 Setup parallel and serial ports
83 Test for math coprocessor
84 Check if keyboard is locked
85 Display any soft error messages
86 Test for option ROM at E0000h
A0 Error found in 256KB or 1MB RAM IC in lower 640KB
A1 Base 64KB random access and data pattern test (only in 386APR and Presto 386SX BIOS)
A9 Initialize on board VGA controller (Presto 386SX BIOS)
B0 Error in 256KB RAM IC in 640KB
B1 Base 64KB random access and data pattern test (only in Presto 386SX BIOS)
E0 Return to real mode and initialize base 64KB RAM (Presto)
E1 Initialize 640KB RAM (Presto)
EF Configuration memory error - can't find memory
F0 Test shadow RAM from 04000h
00 Call the interrupt 19 boot loader

Chips & Technologies BIOS Post Codes:


00 Error in POS register
01 CPU flag register failed
02 CPU register test failed
03 BIOS ROM checksum failed
04 DMA controller test failed
05 System timer IC failed
06 Base 64K RAM failed address test: not installed, misconfigured, or bad addressing
07 Base 64K RAM failed data test
08 Interrupt controller failed
09 Hot (unexpected) interrupt occurred
0A System timer does not interrupt
0B CPU still in protected mode
0C DMA page registers failed
0D Refresh not occurring
0E Keyboard controller not responding
0F Could not enter protected mode
10 GDT or IDT failed, Keyboard controller failed
11 LDT register failed, Keyboard controller failed
12 Task register failed, Keyboard controller failed
13 LSL instruction failed, keyboard controller failed
14 LAR register failed, Keyboard controller failed
15 VERR/VERW failed, Keyboard controller failed
16 Keyboard controller gate A20 failed
17 Exception failed/unexpected exception
18 Shutdown during memory test
19 Last used error code
1A Copyright checksum error
1B Shutdown during memory sizing
1C Chipset initialization
50 Initialize hardware
51 Initialize timer
52 Initialize DMA controller
53 Initialize 8259 programmable interrupt controller
54 Initialize system chipset
55 Setup EMS configuration
56 Entering protected mode for first time
57 Size memory chips
58 Configure memory chip interleave
59 Exiting protected mode for first time
5A Determine system board memory size
5B Relocate shadow RAM
5C Configure EMS
5D Set up wait state configuration
5E Re-test 64K RAM
5F Test shadow RAM
60 Test CMOS RAM
61 Test video
62 Test and initialize DDNIL bits
63 Test protected mode interrupt
64 Test address line A20
65 Test memory address lines
66 Test memory
67 Test extended memory
68 Test timer interrupt
69 Test real time clock (RTC)
6A Test keyboard
6B Test 80x87 math chip
6C Test RS232 serial ports
6D Test parallel ports
6E Test dual card
6F Test floppy drive controller
70 Test hard drive controller
71 Test keylock
72 Test pointing device
90 Setup RAM
91 Calculate CPU speed
92 Check configuration
93 Initialize BIOS
94 POST Bootstrap
95 Reset IC's
96 PEAK: System board POS. NEAT/OC8291 ELEAT: Test /initialize cache RAM and controller.
97 VGA power on diagnostics and setup
98 Adapter BIOS
99 Re-initialize DDNIL bits
A0 Exception 0
A1 Exception 1
A2 Exception 2
A3 Exception 3
A4 Exception 4
A5 Exception 5
A6 Exception 6
A7 Exception 7
A8 Exception 8
A9 Exception 9
AA Exception A
AB Exception B
AC Exception C
AD Exception D
C0 System board memory failure
C1 I/O channel check activated
C2 Watchdog timer timeout
C3 Bus timer timeout

LANDMARK motherboards:

Landmark Jumpstart XT BIOS Post Codes:
01 Jump to reset area in BIOS ROM
02 Initialize DMA page register
03 Initialize DMA refresh register
04 Clear all RAM
05 Perform RAM test on first 64KB
06 Clear first 64KB
07 Initialize BIOS stack to 0FC0h
08 Set the equipment flag based on XT switches
09 Initialize default-interrupt vectors
0A Initialize the 8255 parallel interface, if it exists
0B Initialize the 8259 PIT and enable interrupts
0C Setup adapters and peripherals
0D Setup video system
0E Initialize the video system
0F Initialize the equipment
10 Initialize memory configuration
11 Setup system timer function
12 Initialize system timer
13 Setup time-of-day function
14 Initialize time of day from RTC data
15 Setup and initialize "print screen" function
16 Setup and initialize cassette interface, if available
17 Setup and initialize bootstrap function
18 Setup and initialize keyboard function
19 Enable speaker
1A Setup system timer
1B Enable the RTC
1C Setup timer 2
1D Determine memory size; write 55Aa/AA55 to first and last word in segment
1E Read first and last word of segment
1F Compare first and last words
20 Report found memory size of segment
21 Perform BIOS ROM checksum test
22 Perform complete RAM testing on cold boot
23 Move system stack to bottom of memory and save pointer 40:0E
24 Reset parity after RAM sizing
25 Enable timer and keyboard interrupts
26 Setup the serial and parallel ports
27 Setup the game port
28 Setup the floppy-disk controller
29 Scan for optional ROM's in 2KB chucks from C8000h
2A Call the boot loader

Landmark Jumpstart XT BIOS Post Codes:
03 Sound one short beep
04 Initialize the bell tone
05 Enable CMOS RAM
06 Reset video controller
07 Disable parity checking
08 Start memory refresh
09 Clear the reset flag in RAM
0A Test DMA page registers
10 Use CMOS to determine if a soft reset has occurred
11 Check BIOS ROM checksum
12 Test system timer A
13 Test DMA channel 0
14 Test DMA channel 1
15 Test memory refresh
16 Flush 8042 keyboard controller input buffer
17 Reset 8042 keyboard controller
18 Get keyboard type
19 Initialize the keyboard
1A Clear any existing parity
1B Enable on-board parity
1C Test base 64KB memory
1D Test base 64K parity
1E Initialize POST stack
20 Check keyboard type
21 Test protected mode CPU registers
22 Initialize 8259 programmable interrupt controller
23 Initialize all interrupts
24 Test all interrupts
25 Perform DRAM checksum
26 Adjust configuration based on hardware found and CMOS settings
27 Check for presence of manufacturing switch
28 Initialize video controller
2A Test video memory
2B Test video sync
2C Check for auxiliary video controller
2D Change video configuration
2F Initialize the video system
30 Change video interrupt
31 Display any POST messages
32 Test memory and calculate size
33 Adjust memory configuration
34 Enable I/O parity
35 Test 8259 programmable interrupt controller
36 perform byte-swap test
37 Test NMI
38 Perform timer test
39 Initialize system timer A
3A Protected mode memory test
3B Test keyboard
3C Test keyboard interrupt
3D Enable A20
3E Reset hard disk controller
3F Setup floppy disk controller
40 Test floppy drive system
41 Setup keyboard
42 Enable interrupt timer
43 Check for dual floppy disk/hard disk controller
44 Locate floppy drive A
45 Locate floppy drive B
46 reset hard disk controller
47 Enable slave DMA
48 Locate any external ROM's
49 Initialize the parallel ports
4A Initialize the serial ports
4B Initialize the math coprocessor
4C Read CMOS RAM status
4D Check CMOS configuration against detected hardware
4E Initialize timer ticks
4F Enable IRQ9
50 Enable on-board parity
51 Run any add-on ROM's
52 Enable keyboard interrupt
53 Reset the parallel port
60 Check for any errors
61 Sound one short beep
62 Print sign-on message
64 Call interrupt 19 boot loader

Landmark Supersoft AT BIOS Post Codes:
11 CPU register or logic error
12 ROMPOST A checksum error
13 ROMPOST B checksum error
14 8253 programmable interrupt timer channel 0
15 8253 programmable interrupt timer channel 1
16 8253 programmable interrupt timer channel 2
17 8237 DMA controller 1 error
18 8237 DMA controller 2 error
19 DMA page register error
1A 8042 keyboard controller error
21 Scan 16KB critical RAM error
22 Memory refresh error
23 CPU protected mode error
24 8259 interrupt controller 1 error
25 8259 interrupt controller 2 error
26 Unexpected interrupt detect
27 Interrupt 0, system timer, error
28 CMOS RTC error
29 NMI error
2A Locate and test math coprocessor
31 Keyboard controller error
32 Stuck key detected or CMOS RAM error
33 Floppy controller error
34 Floppy disk read error
35 MDA video memory error
36 Color video memory error
37 EGA/VGA RAM error
38 BIOS ROM checksum error
41 Memory error
42 Refresh fault
43 Display problem
44 Display problem
45 Display problem
59 No monitor detected

Phillips BIOS Post Codes:
0A DMA page-register R/W bad
10 CMOS RAM R/W error
11 System BIOS ROM checksum error
12 Timer A error
13 DMA controller A error
14 DMA controller B error
15 Memory refresh error
16 Keyboard controller error
17 Keyboard controller error
19 Keyboard controller error
1C Base 64KB RAM error
1D Base 64KB RAM parity error
1F LSI sync missing
21 PVAM register error
25 System options error
2B Video sync error
2C Video BIOS ROM error
2D Monochrome/color configuration error
2E No video memory detected
35 Interrupt controller error
36 Byte swapper error
37 NMI error
38 Timer interrupt fault
39 LSI timer halted
3A Main memory test error
3B Keyboard error
3C Keyboard interrupt error
3D DDNIL scan halted and cache disabled
40 Diskette error
48 Adapter card error
4C CMOS battery/checksum error
4D System options error
52 Keyboard controller error
6A Failure shadowing BIOS ROM
70 Memory size configuration error

ZENITH 191 Codes:

Zenith 191 BIOS Post Codes:
00 Start of Slush test
01 Processor test
02 cache and CLIO
03 ISP defaults set
04 Entering protected mode
05 Memory SIMM's count
06 Memory controller test
07 Prepared to test block
08 first 1Mb of RAM tested
09 Checksum OEM ROM
10 Lao flash ROM checks
11 F000 ROM checks
12 Aurora video ROM
13 F000 ROM slushed
14 SEP initialized
15 Language slushed
16 Perform video specific tests
17 Done slushing
32 Point interrupt vectors
33 turn on parity generation
34 Initialize system variables
35 Initialize interrupt controllers
36 Check error that occurred
37 Reinitialize SCP warm boot
38 Test CMOS diagnostics, power and reset
39 Reserved or DDNIL status flag check
3A Test CPU reset if 80386
3B Save the CPU ID in GS
3C Slush video ROM at C0000
3D Initialize the video and timers
3E Initialize CMA ports; Clear page
3F Set speed too fast for now
40 Checksum the nonvolatile RAM
41 Initialize configuration
42 Initialize expansion boards from VRAM
43 Turn cache off for memory test
44 Initialize memory counter; Test extended memory
45 Test base RAM
46 Determine amount of system RAM
47 Test and initialize cache if installed
48 Test system timer tick
49 Initialize the write queues
4A Initialize monitor RAM
4B Clear 16K of base RAM
4C Install BIOS interrupt vectors
4D Enable default hardware initialization
4E Determine global I/O configuration
4F Reserved
50 Initialize video
51 Initialize WD90C30 scratchpad register
52 Initialize the keyboard controller
53 Turn off IRQ 12 if mouse is off
54 Wait for user to enter correct password
55 Initialize system clock time of day
56 Test and initialize floppy drive controller
57 Initialize Winchester subsystem
58 Install ROM's starting at C80000h
59 Install ROM's starting at E0000h
5A Initialize SCSI interface
5B Set default I/O device parameters
5C Initialize cache speed and clock
5D Always tell system ROM cold
5E Run with gate A20 off in PC mode
5F Really turn off the SCP
60 Set machine speed using CFG
61 Turn on cache if machine halt
62 Calibrate 1ms constants
63 Enable NMI
64 Test for errors before boot
65 Call interrupt 19 boot loader

ZENITH ORION 4.01

02 Cold boot; Enter protected mode
03 Initialize the main system board
F0 Begin basic system hardware initialization
F1 Clear CMOS status locators
F2 Starting CLIO initialization
F3 Initialize SYSCFG register
F4 DXPI initialization for boot block
F5 Switching cache off
F6 Configure CPU socket pins
F7 Checking for 80387SX math coprocessor
F8 82C206 default initialization
F9 Superior default initialization
FF End of machine specific boot block
04 Check flash checksum
05 Flash ok; jump into flash code (FFFD flash code)
06 Reset or power up
07 CLIO default initialization command
08 SYSCFG register initialized
09 CMOS pre flush error words initialization
10 SCP initialization
11 DRAM autosizing complete
12 Parity check enabled
13 Start of slushware test
14 Slushware at 000F0000h ok
15 BIOS ROM copied to slushware
16 Back in real mode
17 BIOS ROM slushing is complete
18 Video ROM test at C0000
19 Internal video ROM tested
1A Back in real mode
1B Internal video hardware completed
1C CPU clock frequency determined
1E BIOS RAM cleared
20 Reset
21 Continue after setting memory size
22 Continue after memory test
23 Continue after memory error
24 Continue after boot loader request
25 Jump to execute user code
26 Continue after protected mode test passed
27 Continue after protected mode test failed
28 Continue after extended protected mode failed
29 Continue after block move
2A Jump to execute user code
2B Reserved
2C Reserved
2D Reserved
2E Reserved
2F Reserved
30 Exit from protected mode
31 Test reset passed
32 Check for ROM checksum; Warm boot
33 Clear the video screen on
34 Check system DRAM config update CMOS TOTAL MEM SIZE value
35 Preload CMOS; Check CMOS contents
36 Turn off the UMB RAM
37 Turn parity generation
38 Initialize system variable
39 Check for error in power
3A Initialize SCP mode
3B Test CMOS diagnostics power reset
3C Test CPU reset 80386 and determine state number
3D Save CPU ID and processor T
3E Initialize the video and timers
3F Initialize DMA controller ports; Clear page
40 Set speed to fast for now
41 Test EEPROM checksum
42 Enable/disable parallel/serial ports, floppy disk controller, hard disk controller
43 Flush external video BIOS if on CMOS
44 Turn cache off for memory
45 Test extended RAM from 0-16K
46 Test base RAM from 0-64K
47 Determine amount of memory in system
48 Set warm boot flag
49 Clear 16K of base RAM
4A Install BIOS interrupt vector
4B Test system timer
4C Initialize interrupt
4D Enable default hardware initialization
4E Determine global I/O configuration
4F Initialize video
50 Initialize WD90C30 scratchpad
51 Check for errors before boot
52 Reserved
53 Test system and initialize
54 Reserved
55 Initialize the keyboard processor
56 Initialize the PS/2 mouse
57 Configure CLIO for mouse
58 Configure CLIO for LAN
59 Configure CLIO for SCSI
5A Configure CLIO for WAM
5B Wait for user to enter code
5C Initialize system clock TOD
5D Test and initialize floppy drive sensor
5E Check for Z150 style disk
5F Initialize Winchester hard disk subsystem
60 Set default I/O device parameters
61 Get LAN ID info from LAN
62 Install ROM's at 0C8000h
63 Install ROM's at 0E000h
64 Initialize SCSI interface
65 Run with gate A20 off
66 Really turn off the SCP
67 Set machine speed using CMOS
68 Turn off cache
69 Calibrate 1ms constants
6A Enable non-maskable interpreter
6B reserved
6C Clear the warm boot flag
6D Check for errors before boot
6E Call to interrupt 19 boot loader

Zenith BIOS Post Codes: (General)
01 VGA check
02 MDA initialize
03 Initialize video
05 Set hard reset
07 Check ROM at E000
08 Check ROM shadow at F000
09 Remap video ROM at E000
0C CMOS RAM/8042 keyboard controller test
0D DMA controller test
0E DMA page register test
0F Test 64K base RAM
10 Test base memory
11 Second VGA unit
12 mono initialization
13 Real time clock/CMOS RAM test
15 CPU register test
16 CPU addition test
17 Real time clock/8042 keyboard controller test
18 Enter protected mode
19 Testing memory
1A Test extended memory
1B Leaving protected mode
1C Testing system board
1D Testing system board
1E Testing system board
1F Bus sizing
20 Set BIOS data area
21 Testing DMA controller
22 checking C800 for ROM
24 Testing base memory
25 8042 keyboard controller test
26 8042 keyboard controller test
27 8042 keyboard controller test
28 Memory parity test
29 Programmable interrupt timer test
2A Testing floppy disk drive(s)
2B Testing floppy drive controller and drive(s)
2C Testing hard disk controller and drive(s)
2D Checking CMOS settings
2E Soft configuration
30 Checking adapter ROM's
31 Checking CMOS settings
32 Enabling interrupts
33 Soft configuration
34 Soft configuration
35 Jump to boot code
00 Booting the operating system