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Low-level working of laptops.

By lamo ยท 10 replies
Apr 1, 2008
  1. In this thread, i'll try to describe and answer of some questions about low-level working of laptops. this is about BIOS loading, EC/KBC controllers work,common problems with southbridge faulty etc. i'll be wait for community questions. don't ask me how to unlock dell,HP,IBM laptops, and don't ask me to generate some master passwords. but you can ask me how password systems works in laptops.

    this particular case for beginning:
    toshiba tecra 8100,8200. sometimes you can turn on laptop and listen beeps, which points to RAM failure, but you're sure that memory modules are fine. this problem is connected with bad soldering of memory slots. you can see this bad soldering only using binocular magnifier. the solution is resolder memory slots, using micro-soldering equipment.
  2. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    Why is it that some laptops seem to automatically create a password?
    I have seen this here before. Where a user swears that no password was ever used in bios, then all of a sudden their laptop asks for a password at startup.

    Are some laptops set up for default password, or is it some chip on board gone mad?
  3. lamo

    lamo TS Rookie Topic Starter

    kimsland, the self-creation of password is connected with errors and bugs in bios. and, don't forget about some spyware and viruses. this is confirmed information, that some of viruses can create a power-on password, and even HDD password!
    hint: the power-on password(POP) and administrator password are different thing. while the POP is storing in CMOS memory and can be removed by disconnecting the CMOS battery from laptop MB, but administrator password is storing in energy-independent memory(eeprom or KBC controller). however, there's no difference for dell laptops between admin password and POP (at least as i know, and this is unconfirmed data, sorry, i didn't have much time to check this).
    PS. you don't need to be skilled to create some software which creates POP. but you have to be skilled to write tool, which create admin password or HDD password :)
  4. lamo

    lamo TS Rookie Topic Starter

    another byte of data.
    videchip failure diagnostics. when you turn on laptop, sometimes you can see vertical stripes on the LCD(but external monitor may be ok, or may show same image with these stripes). it's important to differentiate between LCD faulty and videochip faulty(LCD failure stripes has 1 pixel thickness and may disappear during work). second symptom is various "noise" on display. and one major symptom: windows won't load when original driver for certain videoadapter is installed. in those cases described above the solution only one: replace videochip(with videomemory reballing), replace videocard(in some laptops there's MXM1 or MXM2 videocards), or replace motherboard. in some cases it's cheaper and faster to replace videochip(that's of course if you have acceptable equipment :) )
  5. roland_xp_80

    roland_xp_80 TS Rookie

    Can you find my bios password??

    Anybody please help me to get my bios password. I need bios password for del latitude d810.. this is really urgent..

    Please help me.. thanks..
    Service Tag : DKFSZ1J
    System Number : DKFSZ1J-595B
    Express SERVICE Code: 295-340-399-11

    Please help me.. thanks..
  6. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

  7. Kegtapper

    Kegtapper TS Rookie Posts: 17

    The POP password cannot be removed by disconnecting the CMOS battery in DELL's since Pentium IIIm. Nor many other Pentium 4's today. They store the password in a 2-Wire Serial EEPROM. Typically 8 pin (14-16 pin for some Thinkpads). It has to be replaced, read or erased. Atmel and MX are some of the major chips.

    Even newer Dual Core, store theirs in a TCM/TQM module, which takes a 'snapshot' of the system parts, and your password for protection (together). If the chip is changed, the laptop is still locked. It has to be read or erased.
  8. lamo

    lamo TS Rookie Topic Starter

    Kegtapper, this information is right for dell laptops, but POP can be removed by disconnecting CMOS battery(at least in IBM,Acer,Asus laptops). btw, IBM is using the atmel 24rf08 eeprom, and you can't read or erase this eeprom using simple i2c programmer.
  9. lamo

    lamo TS Rookie Topic Starter

    add: that's because, i say, that "paperclip method" is dangerous. you can damage KBC firmware, or even burn it. and if you damage the firmware you can only replace the controller from same MB. SMSC controllers have frimware that changes only if you reflash it, same as H8 microcontrollers(SONY laptops). but most of NS,Winbond KBC controllers are loading their's firmware from BIOS image during powering on.
  10. Kegtapper

    Kegtapper TS Rookie Posts: 17

    re: Atmel 24rf08 - IBM uses 2 versions of that chip. 8 pin in T & R-Series and 14 pin A-series.
    re: CMOS Battery - like I said in older products you mentioned. I generally clear 6-8 a month in various machines.

    i2c programmer alone is not enough, you'll need software also decrypt text. This is information not from what I have read, but what I do. I've made 2 of them so far and bought a JDM reader for other larger chips ~$12..

    BTW- I never use the paper clip method, especially in IBM which would leave CRC errors in BIOS making it one (or 2) more thing(s) to do.
  11. lamo

    lamo TS Rookie Topic Starter

    kegtapper, the paperclip method won't work with IBM, because you have to do command "reset Access pages" before writing. the paperclip method dangerous because you can make a mistake and short for instance 3.3v to GND and make nigh current peaks in 3.3v bus. the 24rf08 communicates directly with H8 KBC controller which responsible for powering on, controlling main voltages in laptop and many other things. 14-pin version of 24rf08 was in all T2x series, except T23(don't remember exactly, i'll check it tomorrow i have a t23 which waits for northbridge replacing).
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