What was the first OS you ever used?

Yes and NT is my second favourite OS. Shame these people are no longer running the show and NT has become so saddled with terrible, burdensome middleware.

It is a shame indeed because NT was a tour de force of design and ahead of its time. Beneath the painted, gaudy mess of Windows today, the sound architecture of the house is still there.
 
The very first was Apple DOS. Shortly after Commodore Basic.

I've tried plenty of OSs, CP/M, Berkely Unix, Minix, Xenix, AmigaOS, GeoS, MS-DOS, PC-DOS, DR-DOS, MacOS, Next, lots of Linux distros, OS2, and every version of windows, just to name a few.
 
Win95 - Man I remember the reformatting effort of that beast. Something like 25 3.5 floppies. What a p.I.t.a - uh oh, lost your boot floppy? Well now, more fun! It’s like a re-formatting afternoon, put a disk in, go jump on the trampoline with the doggo for 5 min or so, rinse and repeat. Cd-rom could not come soon enough.
 
DOS and Window 3.1 are the ones I first remember using. No one to show me how to use DOS, I figured it out on my own because I wanted to play the games on the 5.25" floppy disks.
 
First PC was an DOS 5, win 3.11 on a AMD 386 DX 40mhz, 4mb EDO RAM, 120mb hdd, 512k trident vesa card. Later got a Creative multimedia kit with SB16, 2x cdrom, which felt like stepping into a new era! Had to upgrade my vga to a 2mb S3 trio968 to play The 7th guest on CDROM without hiccups. good ol'days. All that in Brazil 1991
 
Burroughs mainframe, FORTRAN, IBM punch cards
Used to use Fortran and punch cards on IBM S/360 clone (EC 1033)

BASIC programs, hand entered, saved on cassette tape
Used tape to record my creations on MZ-821. Basic, hexa code of Z80 and Turbo Pascal.

MSDOS on an 8088
At uni computer lab there was 80286 used as server for 10 other PCs with 8088, CGA card (4 colors) and no storage device (no HDD, no floppy, no tape ... nothing). They booted from that 80286 trough ArcNet (different HW and protocols than Ethernet) and used part of memory as RAMdisc.




 
IRQ jumpers, autoexec.bat, msconfig.sys ...
It worked.
It took 10~15 years to make USB working.
PnP at that time was read as ... Plug and Pray

... manually installing drivers for a $240 CDROM that was NOT a burner!
Had to buy SCSI adapter for my 1st CD burner to burn CDs at breakneck speed of x2.
And worried to touch the mouse to not crash the burning process with some inappropriate windows response.

Sometimes I am feeling old.

 
I remember I had an Amstrad CPC 6128 back in 1985/86. It ran on AMSDOS (Amstrad DOS) with Locomotive BASIC. I bought various games on 3 1/2" floppy disks and messed about with writing code etc... those were the days [sigh].
Don't forget it could also run CPM with the |CPM command. Had a 464 with greeen screen before getting a colour 6128 later on (finally let it go when I sold it 5 years ago).
 
First "OS" that wasn't just a Basic interpreter that I used as a kid was GEM/TOS on the Atari ST. Then MacOS 6 on a bootsale Mac Classic that I had for a while, then Windows 95 on a hand-me-down 486 (and continued with Windows from there).
 
Had a VIC-20 when I was a kid… early 1980s… Commodore BASIC 2.0… still have it - but the tape drive is a bit wonky and not really worth booting up any more…
 
Never really played with it, but I did see & use a TRS-80 once.
But my own first computer OS was DOS 3.31.
I remember when DR-Dos came along, switched to that. I think when Windows 3.11
came along I had to wait for DR-Dos to be "patched" because MS didn't give Digital Research
the code so they could make DR work with 3.11.
It wouldn't install or something...been too long to remember what the problem was.
 
Brief timeline: Dos 6.22 ->Win 3.1 & Macintosh & NeXTSTEP -> Win 95 -> Win ME -> Windows 2000 -> Windows NT -> Windows XP -> Windows Vista -> Win 8 & Fedora & Centos -> Win 10 -> Win 11
 
EXEC-8 (on UNIVAC 1108) while working a summer job during high school at the National Bureau of Standards in Gaithersburg MD. When I was alone on the raised-floors deep in the maze of corridors on the 1108 I could swear that beast was alive. Took a break when the IBM 360 was phased in and then picked up again with MS-DOS on a 12MHz 286 in the very early 80s.
 
Couple of things I noticed on this one.

1. Most of you are at least as old or older than me, Which surprised me a little.

2. A LOT of you use early IBM PC clones or early MSDOS/Windows stuff which was really not as prevalent here in the UK.
 
Love this question! I felt scared of reading the comments first, but man am I relived to see the answers. LOL

MS DOS on a 386 at home, playing Dune and the Sierra clickers, barely any studying done.

Apple DOS 3.3 on an Apple II at school, drawing shapes on BASIC, sneaking in during recess to play Prince Of Persia.

Here's one you might not know, I also had the Japanese MSX running a version of MS BASIC where I had the privilege of playing the original versions of Metal Gear, Castlevania (Vampire Killer at the time), Gradius 2 (called nemesis 2), Penguin Adventures (Kojima's first game ever), Dragon Slayer by Square, Kung Fu 1&2 (fighter by Konami), F1 Spirit by Konami, and Ninja by Hudson.

Looking back, it wasn't intuitive. You literally had to learn the secret handshake to boot a program. Mistakes were unforgiven. But it taught me how to learn computers, that they are literal, meaning they taught me to always check my own work and never suspect maliciousness, that the interfaces we use today are glossy surface veils that we can hack through, ok I said enough.
 
CP/M. On a system I put together myself (as one had to, way back) comprising a box with power supply and S-100 bus, a CPU card with a mighty, all-powerful 4 MHz Z80 CPU, a memory card with a massive 64 kbytes of dynamic RAM, a single floppy disc drive with its interface card and a “communications” interface card with two RS-232 (serial) ports (one for my fifth-hand terminal) and one Centronics (parallel) port for an Epson dot matrix printer that came later when I had the cash.
 
Color BASIC 1.0 on a TRS-80 Color Computer (circa 1978).

But my favorite of all time was Atari TOS (with GEM) on the ST's.
GEM was also available on the Amstrad PC1512/1640 range of IBM compatibles (was included with MS-DOS 3.1 or DR-DOS as you had the option). MS-Windows was really nowhere to be seen in the UK (and Europe) until Win 3.0 (and above - 3.11 for workgroups being the outbreak version) made an appearence when 80386's were the norm. I was lucky enough to break my teeth on a large selection of home computers: Ti99/4 (not the 4a), Acorn Electron, BBC model B (at primary/elementary school), Amstrad CPC464, 6128, PCW8256, Commodore 64, Tatung Einstein, Sharp MZ700 and PC1640 ECD. Missed out on the Atari ST/Amiga/Archemides battle as went from PC1640 to a beige box 486 and then a Pentium 133, AMD Duron and onto one beige box PC after another.
Strange how we now all talk about the CPU and GPU's in our systems - back in the 80s we didn't argue about the 6510 v the Z80 v the 6502.......
 
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