[HN Gopher] PC DOS 1.1 from Scratch
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PC DOS 1.1 from Scratch
Author : kencausey
Score : 83 points
Date : 2021-09-10 15:30 UTC (7 hours ago)
(HTM) web link (www.os2museum.com)
(TXT) w3m dump (www.os2museum.com)
| h2odragon wrote:
| The detailed, loving description of the baroque boot process
| takes me back to my days, shortly after that period, of cracking
| and making "boot only" floppies that either wouldn't show files
| if read normally, or showed different files; while having
| something else happen if you booted from it.
|
| _Twitch_ and _shudder_
|
| "Pinball Construction Kit" was a commercial game that used their
| own floppy format.
| bitwize wrote:
| Microsoft Flight Simulator (before version 3) was another. The
| DOS view of the disk contained a single file, FS.COM, 60 bytes
| long.
| dragonwriter wrote:
| > "Pinball Construction Kit" was a commercial game that used
| their own floppy format.
|
| Software (IME, mostly games, but then my experience with
| software at the time was game-heavy) that worked that way was
| quite common.
| h2odragon wrote:
| One of my gigs was for someone selling essentially locked
| down spreadsheets. to their tiny niche markets, that was
| effective DRM and an appreciated convenience.
|
| > my experience with software at the time was game-heavy
|
| Well put. min too :)
| butterisgood wrote:
| I returned two copies of Pirates! thinking the disk was not
| working until I realized you had to boot from the game disk and
| not DOS.
| tpmx wrote:
| Also Sega Zaxxon iirc, the only original PC game I had back in
| the 80s. (I guess the copy protection scheme kinda worked?)
|
| "Cracked" copy:
|
| https://archive.org/details/msdos_Zaxxon_1984 (it's kinda hard)
| WalterBright wrote:
| What's interesting about this is I feel I could write DOS from
| scratch with little effort these days. But it would have no value
| today.
|
| The software I write today is _far_ more complex than what was
| available in the early 80 's.
| mhh__ wrote:
| The machine description files in GCC and LLVM are probably
| enough lines to fit a C compiler from the early days in them.
|
| The sophistication is a good thing but for god's sake give me
| my latency back.
| tpmx wrote:
| I've had similar thoughts about this development. (Not about
| myself being able to rewrite DOS without much effort - but I
| don't doubt that you could!)
|
| The sophistication of some individual projects today rivals
| major industry efforts back in the early 80s.
|
| I think it boils down to mostly these things:
|
| a) back then the number of software developers was perhaps
| 100x-500x smaller than today - so there was simply a much
| smaller pool of smart people. (But also: Today we have a _much,
| much_ larger pool of kinda meh people.)
|
| b) there was no widespread internet access, so developers
| learned new concepts very slowly, often re-inventing them on
| their own. also, smart people often gut stuck in places where
| they had no chance of excelling.
|
| c) better tools now: much better screens, windowing systems,
| mice, better editors, source code version control tools, SSDs
| instead of floppies, VMs, trivial networking, pdf readers,
| archive.org/etc, web browsers/services/sites, etc etc.
| WalterBright wrote:
| I don't understand it, myself. The small size of DOS and its
| utilities make it look, in a word, trivial to me. I've read
| about the early days of Microsoft and how they struggled to
| get DOS finished, and from the perspective of today am more
| or less baffled.
|
| A part of the problem was they wrote in assembler. Today, I
| would not write it in assembler. I'd write it in C (or
| DasBetterC!) and get it all complete and debugged. Then, I'd
| hand translate it to asm. I expect this would go 10x faster.
|
| I'd also develop it on a Unix computer, using an emulator to
| debug it, much like how Gates/Alan developed Basic. (That was
| a really smart move by those two.)
|
| I don't use IDEs myself, but git is an absolute game changer.
| wvenable wrote:
| You have the advantage, in this case, of knowing what the
| end result is. I can re-write any of my own existing
| applications in a fraction of the time it took to develop
| them initially.
|
| But I agree that it all looks trivial. I'm developing an OS
| for a custom 8bit system and it's pretty slow going even
| though it's trivial. Of course, if I was cloning an
| existing OS it would go a lot faster but obsessing over the
| fine details is part of the fun.
| tpmx wrote:
| Nit: Gates/Allen developed their basic on an 8080 emulator
| running on a PDP-10 (1966), so it wasn't running Unix. The
| PDP-11 (1970) was the first computer to run Unix. I agree
| that it was a pretty smart move to emulate the 8080 on a
| mainframe computer.
|
| Source: https://en.wikipedia.org/wiki/Microsoft_BASIC +
| https://www.inwap.com/pdp10/xkleten.txt
| animatedb wrote:
| I imagine you may know a lot about this, but what
| OS/machine were they using to develop it? PDP-11?, CPM?
| What editors did they use? Line editors? Which machines did
| they use to test on? Most drives and even RAM was
| unreliable back then and everything was small. I imagine
| there were plenty of obstacles back then. I remember using
| CPM where floppy disks had to be swapped between the editor
| and compiler, and your program may fit on another floppy
| disk.
| DoctorNick wrote:
| "To compile PC-DOS from scratch, first you must invent the
| universe." - Carl Sagan
| redleggedfrog wrote:
| For a minute I thought it was PC DOS 1.1 rewritten in the Scratch
| language, and I was ready to be impressed. Still a good article.
| I actually used DOS 1.1, when it came out. I'm old.
| h2odragon wrote:
| Ah, but did you have to program it? Have you known the horror
| of the FCB? https://en.wikipedia.org/wiki/File_Control_Block
| OneEyedRobot wrote:
| I think my fingers still know edlin.
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