14 ms·

The 640 K Barrier

244 points by mwcampbell 10y ago

13of40 10y ago
I attended a talk by Bill Gates several years back, where he stated that when IBM was developing the PC, he tried to convince them to base it on the MC68000, and that their decision to go with the 8088 set personal computing back a decade. As the article points out, though, there were a ton of 68000 machines that ultimately got left in the dust by the PC, so I wonder how it would have really turned out.
- valuearb 10y ago
  Intel turned out way better than Motorola (and everyone else) at increasing transistor density.
  - pm90 10y ago
    Well, maybe that was because they had a lot more money to throw at R&D? Not saying either way, but it looks like this was the opportunity that really pushed Intel into the big league. To their credit, they used it wisely and kept making better chips.
    - LordKano 10y ago
      Intel's chips continued to advance after those designed by the AIM Alliance (Apple IBM Motorola) hit their ceiling, so I'm not sure it was just R&D budget. I was impressed by the performance of the PowerPC 970 but much sooner than expected, Intel's (and AMD's) lineup made it irrelevant.
    - astrodust 10y ago
      It's more like Intel had a CEO that understood what it took to win in the CPU business and Motorola ended up with a CEO that printed out his email and banned Macs from the company when they were one of the few licensees making Apple Mac clones and Apple was one of their biggest buyers of CPUs.
  - Zaak 10y ago
    I would attribute that more to Intel's revenue than anything special about the company though.
  - tyingq 10y ago
    They didn't really trounce all the RISC vendors until AMD showed them the way with x64. They wasted a lot of time on Itanium.
  - Keyframe 10y ago
    As others have noted, Intel was in cash and drove on top of that mostly. Not to belittle Intel though. Motorola would do well, as evidenced by 88k and later PowerPC with Apple and IBM... but at that point in time it was already too little too late.
- thelazydogsback 10y ago
  Should have been the Z-8000! I would have liked to have seen Zilog/Motorola be the battle rather than Intel/Motorola. (But maybe that's just my TRS-80 bias showing...)
- EliRivers 10y ago
  As I recall (although it is only a recollection, so if someone's got better evidence than my unreliable memory I stand corrected), what drove the triumph of the PC was not that it contained an 8088, but the software available for it and the ease with which third parties could make compatible hardware (and indeed, clone the whole thing). I suspect (but cannot prove) that both of those could still have happened if they'd gone with the MC68000.
  - gmiller123456 10y ago
    To cite "Triumph of the Nerds" again. There were several things that came together to make it possible. IBM's support for it was pretty essential, their bureaucracy being incompatible with a fast changing market leading to them outsource all of the components, and the simplicity of the system making it easy to reverse engineer.
    - digi_owl 10y ago
      In a sense the PC was a recreation of the Altair, but with extended IO features out of the box.
  - Keyframe 10y ago
    I'd argue for 'open' hardware platform more than anything. Take a look at other personal computers of the time, within an order of (or two) magnitude price up or down, like Mac, Amiga, Atari, SUN, HP(UX), and SGI. They all had great(er) software and hardware and more advanced OS' and features, but got trumped quickly. On the software side, PC had business productivity from the start which could be used as an argument on the software front (Lotus 1-2-3, namely).
- AnimalMuppet 10y ago
  IIRC, a big part of the reason for choosing the 8088 was that Intel successfully generated some FUD about Motorola's ability to manufacture the 68000 in the quantity needed for the PC.
  - Aloha 10y ago
    No. IBM had a second source requirement on procurement, Intel was willing to license or already has licensed the 8088 to be manufactured by someone else, and Motorola was not.
    - xenadu02 10y ago
      AMD was the second source BTW. The licensing agreement allows cross-sharing which is why Intel was able to adopt AMD64.
      - digi_owl 10y ago
        There were others as well. VIA is still around, while others have folded or merged (with Intel forbidding a license transfer).
- gmiller123456 10y ago
  And in "Triumph of the Nerds" Ballmer said working on OS/2 set them back 10 years too. So, I guess with these two setbacks together, the PC became un-invented.
- digi_owl 10y ago
  I seem to recall reading that the compatibility between 68k variants were less then stellar. Not sure if it was Filfre, in relation to the Amiga, or elsewhere.
  - foobiekr 10y ago
    the 68k family did not maintain total binary compatibility for supervisor mode from chip to chip. this was a pain. the 24 bit addressing thing, yeah, that was a hazard as well.
- ajross 10y ago
  The 68k had its own list of dumb architectural mistakes, FWIW. Registers were 32 bits wide but load addresses were 24 bit -- the CPU just ignored the high 8 bits, which led to programmers trying to cheat and stuff things like tag bits into pointers, which then broke on the 68020 which expanded the address space. The hardware bus was async (!!!), meaning you had to arrange correct clock synchronization for every one of your peripherals independently. (c.f. "DTACK grounded", the classic 'zine of the 68k hobbyist). The exception handling was insanely complicated, and even then they got it wrong in the first version: faulting instructions couldn't be restarted, making the use of an MMU impossible even in principle. They fixed this (via dumping even more undocumented complexity onto the stack) in the 68010, which was essentially a "patch release" to the part that was needed by the Unix workstation community. It's true that starting the PC with a 32 bit flat address space would have saved headaches in the late 80's, and it's likely that the feature set in Win95 would have arrived a few years earlier. But on balance the mac and unix worlds had not less grief moving off of 68k.
  - Ded7xSEoPKYNsDd 10y ago
    The 8086 also ignored high address bits, and Intel had to add workarounds for that in later CPUs: http://wiki.osdev.org/A20_Line http://wiki.osdev.org/A20_Line
    - ajross 10y ago
      That was a wraparound condition, sort of the opposite of ignored bits. Memory addressing on 8086 inherently adds two registers every time: the pointer and a segment register (which points to a 64k region of the 1M address space with a granularity of 16 bytes). The problem is what to do when the segment plus the address overflows. On the 20 bit original implementation, you just got the rolled-over address. (What you should have gotten was a fault of some kind, of course.) On the 286, the same addition would give a valid address in the second megabyte of memory, which isn't the same memory. So the PC/AT (not the CPU) had a compatibility switch wired that would force the 21st memory address line low in real mode for compatibility with apps that actually relied on the early behavior.
- iconjack 10y ago
  The story I heard at the time was that the IBM team did want to go with the 68000, but Motorola couldn't guarantee enough units.
  - megablast 10y ago
    In those days you had to have a second source for your chips, in case something happens to you. AMD was Intel's seconds source, Motorola had none.
mikestew 10y ago
If one ever wondered why the original PCs were viewed as toys by professionals in the field, this article is a good explanation as to why. Imagine you go from, say, an IBM 370 mainframe which has had virtual memory, VMs, no-execute flags, and considerably more than 640K back in the 60s to...this morass just to use the memory you paid for (and pay you did, back then). Granted, PCs didn't cost a couple of million with a maintenance agreement, but that didn't make them any more useful for running your nightly batch jobs.
- digi_owl 10y ago
  As i learn of the mainframes of yesterday it feels like all the hoopla of _nix on x86 these days is basically rediscovering all those things mainframes did back then...
  - mikestew 10y ago
    Well, an original PC cost, what, $5K back in the day? A new 3081 370-compatible from the early 80s was multiple millions (can't find hard prices quickly, so guessing). I'll bet the CPU in the mainframe alone cost multiples of an entire XT. Mainframe engineers had a little more breathing room when making their design decisions. So we can look at it one of two ways: those kids today, all excited about VMs and stuff we had in the 60s. Or, holy crap, I can do stuff on my phone that used to take a multi-million dollar mainframe.
  - astrodust 10y ago
    Hypervisors are all the rage today but that's so 1970s in the mainframe world. Welcome to the party, kids.
    - digi_owl 10y ago
      Indeed. What I find most "puzzling" is the lack of acknowledgement of this in the business. Its like it is a whole new, almost magical, thing that the devs dreamed up. I wonder if it has to do with how the microcomputer world had to almost bootstrap itself without any input from the mainframe people, because the latter considered the micros little more than toys. And this continue into the present, as a large segment of the business is self taught. And by now even going to university will not expose you to mainframes, as they have largely been abandoned in favor of clusters.
thelazydogsback 10y ago
Should have some props in there for Topview, Desqview, and especially QNX...
- zwieback 10y ago
  Props from me. I loved Desqview, it worked great. I didn't really use high memory other than for Desqview and SmartDrv. Once the 386 came around it was so much easier, Watcom C++ was my favorite way to take advantage of my luxurious 16MB I could afford at the time.
  - thelazydogsback 10y ago
    Compiling helloworld.c with one floppy and no hard drive on the original PC required one disk for each of the following: (1) source code, (2) cpp.exe, (3) cc1.exe, (4) cc2.exe, (5) lib manager (can't remember the name - something like "marion"?), (5) and the linker -- I think it was 8 floppy swaps total. It blows my mind that my first HD was 5 MB and cost $800. Also missing was the programming side things: LocalAlloc vs. GlobalAlloc, low-mem HWNDs, etc. - ug - don't miss that...
    - ThomaszKrueger 10y ago
      And the FAR PASCAL calls as well.
    - 13of40 10y ago
      I realized yesterday that for years I've been mentally measuring data by how many Amiga 3.5 inch disks it would take to store. Noticed this when I was patting myself on the back for getting the build output of the tool I'm working on down below ~60 disks.
    - digi_owl 10y ago
      At the same time the system felt much more controllable and understandable from a user POV. And I sometimes feel that Linux is going through a similar transition, at least on the user space level.
korethr 10y ago
This article is bringing back memories. Not just of fiddling with CONFIG.SYS and AUTOEXEC.BAT, but fiddling with the sound card too, as was mentioned in passing. As mentioned in the article, I did indeed feel a sense of triumph when I finally got Wing Commander: Privateer to run. As EMS was a kludge that sucked up high memory for its mappings, I eventually had a fancy CONFIG.SYS with different menu options for different memory setups, depending on which game I wanted to play. Good times.
- spapas82 10y ago
  Couldn't agree more! I was like 10 years old in the 90's (before Windows 95 on 1995) when all good games run on DOS. I had became an expert on how to edit config.sys and autoexec.bat to enable EMS or XMS or save a few KB off the 640 kb limit - some games needed more than 590 kb from base memory free even though they were also using extended memory! And of course you needed to know exactly your sound card configuration (IRQ number and COM port) and your video driver capabilities and memory size (I started with a hercules and moved over to a trident before getting a 3dfx voodoo). Yes, running a game then was much more difficult than double clicking an icon but it was worth it. The games of that era were great and you could aquire skills (persistance, attention to detail, thinking on finding solutions) useful for the rest of your life - if you were a kid at least!
  - khedoros1 10y ago
    We're close to the same age. I remember that I had certain games with awesome boot disk creation utilities, and I knew which disks would help with which games. Although, those were always just the next step after running memmaker again, hoping that it would find just a little extra (but not really understanding what it was doing). And I remember being a little disappointed when a game only supported the PC Speaker or Adlib, but shrugging, and deciding to be grateful that I didn't have to worry about getting digital audio working too.
    - digi_owl 10y ago
      I think one game that gave me grief back then was Master of Magic. It needed lots of free memory, EMS, and those two plus sound was nigh impossible.
zwieback 10y ago
Shout out to Windows Real Mode, which had a built-in virtual memory manager that swapped out unused memory to disk. All of that required apps to participate, of course, but it could multi-task in the lower 640K.
- LeoPanthera 10y ago
  Astonishingly, Real Mode still exists even on 64-bit Intel chips, and is still the default mode. Booting a modern OS involves a whole stack of bootstraps to jump from Real Mode to Protected Mode to Long Mode. It's duct tape all the way down.
  - digi_owl 10y ago
    That's one of the things I feel FOSS is largely underestimating, the amount of old code running in offices around the world. You can still run programs from the Windows 1.x-3.x era (win16) if you have a 32 bit Windows 10 install. You apparently need the 32 bit version because 64 and 16 bit modes are mutually exclusive (or some such).
    - poizan42 10y ago
      It's because Virtual 8086 mode is unavailable in long mode. So either you would have to switch the cpu in and out of long mode (which probably has a performance penalty and complicates the code), or use the more general purpose virtualization support (which may not be available), or just emulate everything. It not surprising that Microsoft just decided that it wasn't worth it.
  - astrodust 10y ago
    It's a 16-bit CPU with 32-bit extensions running in 64-bit mode.
    - LeoPanthera 10y ago
      Prefix this with "It's a 64-bit CPU pretending to be..." and you've got it right.
jsnell 10y ago
It feels kind of embarrassing to admit that despite years of tweaking this stuff to get games to run as a kid, I never actually bothered to find out what the difference between EMS and XMS was. Or even know the basics of how they both worked. "It's just extra memory, right?". It's bizarre that the computer magazines I read (and obsessively reread) would not have run an article like this.
- zerocrates 10y ago
  > It's bizarre that the computer magazines I read (and obsessively reread) would not have run an article like this. The "Megamemory Explained" graphic used in this post comes from the Jan. 14, 1986 issue of PC Magazine, part of an article called "Enlarging the Dimensions of Memory." It doesn't cover XMS as the 386 was so new as to be effectively nonexistent at the time, but otherwise seems to be a pretty thorough explanation.
  - polpo 10y ago
    And here's another article from 1993 in PC Magazine which goes into detail, and with a bit more accuracy than the original article for this HN discussion (for example, it explains how XMS works on the 286): https://books.google.com/books?id=gCfzPMoPJWgC&pg=PA302&lpg=PA302&dq=xms+loadall&source=bl&ots=rmlgK_Hia9&sig=skK-3_tKMmhbFteI4FgBgnYTUhc&hl=en&sa=X&ved=0ahUKEwjbgMq26aTTAhVdImMKHSnTACUQ6AEIMDAC#v=onepage&q=xms%20loadall&f=false https://books.google.com/books?id=gCfzPMoPJWgC&pg=PA302&lpg=...
    - flomo 10y ago
      Wow, that is the exact article where I learned this stuff from. (Funny how your memory gets jogged like that.) I was an Apple guy and a late comer to the PC world, and PC Magazine was pretty much a must-read back in the day. Lots of good technical content.
- joakleaf 10y ago
  As I recall: you could only access XMS memory by copying. So you had to _copy_ a memory block from above the 1MB barrier to the lower 1MB addressable space to read, and copy back up again to write. EMS was pageable. You could had up to four 16 KB pages below 1MB that were fully accessible, but you had to select which address above 1MB each of those four pages had to point to. So in short, XMS was inefficient, because you had to copy, and EMS was more efficient because you simply decided which part of the extended memory you wanted to map to lower memory. I think, EMS was emulated in real mode on the 80386 chip by using its virtual 8086 mode. This was not possible on the 80286, so the 80286 could only use XMS in real mode. I briefly developed using both EMS and XMS, and as I recall, XMS was somehow less painful to get up and running and generally work with, but the performance conscience part of me obviously favored EMS's paging mechanism. Fortunately, 32-bit memory came along quickly both in the form of Windows and DOS protected mode.
raarts 10y ago
The article mentions confusion. That's an understatement. Information was much harder to come by at the time, you had to rely on articles in computer magazines. Also many bugs existed in memory drivers, not to mention interoperability problems, due to programmers not understanding the issues. This brings back memories, but not particularly good ones.
ThomaszKrueger 10y ago
It should be noted that some level of multitasking was achieved with so-called TSRs (terminate and stay resident programs). My preferred utility of course was Sidekick.
guelo 10y ago
The original mistake was made by the IBM engineers that came up with that memory map. They reserved a few bytes at the beginning and then a bunch of bytes at the end. That really makes no sense. They could have avoided all the pain that followed by putting all the reserved space in a contiguous block at the beginning. Maybe they thought it was easier for application programmers to use smaller address numbers? Or maybe it was due to some hardware shortcut, which wouldn't be surprising considering they had already taken the shortcut of using the 8088 instead of 8086. This kind of story is repeated whenever temporary hacks turn into massive successes, for example Javascript's limitations that still haunt us today. If you dig down into these histories you almost always find that it's not the engineers' fault but shortsighted managers.
- zwieback 10y ago
  I thought it was because it's easier to decode a few upper address lines on the bus so each peripheral is cheaper and easier to build. If you put the hardware addresses in the lower address space you'd have to decode the entire address to see if the access is on your card. I think the real problem was that people didn't want to let go of DOS. OS/2 1.x was a fine OS, especially from 1.2 onward and it ran great on a 286.
  - mschaef 10y ago
    OS/2 may have been fine in the abstract, but set in the context of the time, it left a lot to be desired. Not only did it require a bunch of extra (expensive) memory, it also required new the purchase of new software to take advantage of that memory. (Otherwise it was just a hobbled version of DOS via the compat. box.) Combine that with the $3K SDK cost and the deliberately incompatible PM, there were good reasons it was a hard sell.
    - Zardoz84 10y ago
      One of the big fails of OS/2 was the IBM never had the desire that it would ran on any PC clone. They priorize doing something similar what does Apple with OSX on lesser degree. In other words, there was few drivers for hardware that wasn't on a PS/2 computer. Add to the mix the non cheap SDK...
floatboth 10y ago
I'm really surprised that the DOS extenders weren't the first solution to appear…
- mwcampbell 10y ago
  If I understand the article correctly, DOS extenders weren't feasible until the 386, because the 286 couldn't switch out of protected mode and back to real mode except by doing a full reset.
  - WalterBright 10y ago
    There were effective 286 DOS Extenders. Zortech included the Rational Systems 286 DOS Extender with the Zortech C++ compiler.
    - bni 10y ago
      After reading the article, I am really curious how these could work.
      - cardiffspaceman 10y ago
        We're talking protected mode. The segment register would be an index into a table of segments of memory and the segments would be implemented in your RAM, and all of them would be accessible "at once" modulo the fact that there were only a few segment registers. The DOS extender could hack DOS so that you could in some fashion call DOS through "INT 21h" and it would do something (emulation, call through glue code into real mode etc). The call might require a transition into and out of real mode, which would not be cheap. Sometimes the only way to call DOS was to use "low" memory that was directly accessible from real mode, and you'd need to use special routines instead of malloc/free to manage that memory. You'd still have to call DOS through a hack but the memory arguments of the call would not need to be rearranged within the extender.
psyc 10y ago
For the first decade or so that I was programming, the 640k barrier was as normal as air. Now I do back-of-envelope calculations that tell me a single data structure is 100MB, and I'm like, "Yeah that's fine."
avodonosov 10y ago
Intel could have allowed more memory in the real mode, instead of providing that only in protected mode incompatible with the existing software ecosystem.
polpo 10y ago
This article is a bit inaccurate about XMS. XMS works just fine on the 286; see the original spec [1]. This is done purely in real mode on the 286 with the the A20 line [2] which allows addressing a 64kB area above 1024MB, in combination with the the undocumented LOADALL instruction, which allows addressing even beyond that [3]. [1] http://www.phatcode.net/res/219/files/xms20.txt http://www.phatcode.net/res/219/files/xms20.txt [2] https://en.wikipedia.org/wiki/A20_line https://en.wikipedia.org/wiki/A20_line [3] https://retrocomputing.stackexchange.com/questions/1006/what-is-the-infamous-instruction-loadall-on-the-80286-and-what-was-it-used-for/1011 https://retrocomputing.stackexchange.com/questions/1006/what...
thought_alarm 10y ago
Great read. Are there technical reasons why Microsoft didn't release a Protected Mode version of MS-DOS in the 80s, or was it just a case of trying to push users and developers to OS/2 and Windows? It seems like such a no-brainer, especially since MS-DOS provided so few services to applications anyway. You have MS-DOS 8 and MS-DOS 16, and you let the user choose which version to boot into, or you automatically kick over to MS-DOS 16 when a Protected Mode app is launched. It seems a lot saner than forcing users to muck around in config.sys. That people were forced to deal with the memory limitations of the 8088 PC well into the 90s is just bananas.
- stickfigure 10y ago
  It's not quite that simple. DOS is not like what we think of as an OS today; more like some libraries that sit in RAM at known addresses plus a loader barely smart enough to transfer data from disk to RAM and start execution. All the intelligence is in the application program itself. And those programs were still stuck with 20-bit pointers. It wasn't just a question of rewriting the OS, it was also a question of rewriting all the application software. Which eventually happened.
  - digi_owl 10y ago
    And why I half-jokingly consider unikernels "DOS in a can".
    - throwaway91111 10y ago
      Nothing bars unikernels from running their code in protected memory as the sole non-ring-0 proc.
- JdeBP 10y ago
  Microsoft did. It was simply inside 386 Enhanced Mode DOS+Windows. By the way, MS/PC-DOS provided quite a lengthy list of services to applications. Have a look at DOS parts of Ralf Brown's Interrupt List some time.
orbitingpluto 10y ago
Microsoft Mouse (software release 9.00) from 1993 was a coveted driver back in it's day. If I remember correctly I think it only took 2K of conventional memory and the rest shunted into upper memory. After discovering that on a BBS I rarely needed an alternative config.sys/autoexec.bat.
lordnacho 10y ago
The 640K thing precipitated the first program I ever wrote. If you can call it that. I had a bunch of games I wanted to play in the early/mid 1990s, including Wing Commander. Each one seemed to require it's own config.sys/autoexec.bat, so I wrote a menu type thing to choose the game and do the appropriate setup. The experience made me think about what else I could do by joining a few commands together. I wish the internet had been available to me then, because I would have made much faster progress if something like stackoverflow had existed.
- AceJohnny2 10y ago
  > because I would have made much faster progress if something like stackoverflow had existed. Kids these days have it easy! /s
  - deleted 10y ago
    [deleted]
- 0xADEADBEE 10y ago
  Couldn't agree more. I try not to think about it but if I'd have had the resources available to me back then that I have now, I would be orders of magnitude better. I built my first computer about 17 years ago but dial up was still a thing and I was discouraged from spending time on it so I just did html in the 30 minutes per day I was allowed. If I'd have found a REPL back then, I probably wouldn't feel so inadequate when discussing concepts with my friends at the big 4! It'll work out fine, but later than planned; the spectre of unemployability will start looming in a decade or so, which certainly motivates me!
Zardoz84 10y ago
I rememeber that I was very effective tunning the config.sys and autoexec.bat to grab the max conventional ram. If my memory don't fail, I think that I managed to get ~636-634KiB on my first PC (an AMD 386@40 with 4 MiB of RAM). I usually, launch memmaker, and then fine-tune the config.sys & autoexec.bat . country.sys ? doskey.sys ? ansi.sys ? Remove it! I need moar free conventional ram !
- nvahalik 10y ago
  That was my first thought—hmmm... memmaker.exe ought to take care of this.
supernintendo 10y ago
> "640 K ought to be enough for anybody." Bill Gates never actually said this [1]. There are those who might attribute this to the Mandela Effect. [1] https://www.wired.com/1997/01/did-gates-really-say-640k-is-enough-for-anyone/ https://www.wired.com/1997/01/did-gates-really-say-640k-is-e...
yuhong 10y ago
This reminds me of the OS/2 2.0 fiasco, which is so bad it is one of my favorite topics.
magoon 10y ago
So much time spent optimizing my system to provide as much "conventional memory" so I could run a performant BBS in 640K, with all the drivers and such. It's hard to imagine now.
orionblastar 10y ago
I used to work as a technician getting DOS/Windows 3.X and OS/2 2.X systems working. There was a program I used to identify expansion cards and get the ID number off of them. It could detect memory size as well, but that doesn't work in modern systems anymore. https://sourceforge.net/projects/gconf/ https://sourceforge.net/projects/gconf/ Had a VP with a WANG PC that used Microchannel, he needed Netware, AS/400, and the Wal-Mart client going at the same time and not cut into his 640K of DOS memory. There was a trick to it. First using card IDs I found the option floppies for his expansion cards from CompUServe (As The Internet/WWW was in infancy and our employer paid for CompUServe to research things) and I re-arranged the expansion card memory to leave a 64K area that was not used that DOS could load drivers into it to free up the main 640K memory. At the time Netware and AS/400 used DOS drivers, while OS/2 had OS/2 drivers that could access the memory beyond it. This was before Windows 95 (It was in beta test at the time). I had upgraded the VP to MS-DOS 6.22 used loadhigh and memmaker and other things and managed to get all three networks working with most of the 640K area free. No other tech had done things like that before. I studied programming in college, but this gconf tool I wrote had helped me out a lot. I wrote it in college and then modified it to be named whichnet so that it could read Arcnet or Starnet network cards and use the correct Netware driver for DOS on a boot floppy disk. Either by using the expansion card ID to detect the right card or by reading ROM memory and look for patterns or a signature. It had worked 99% of the time, and in the 1% it had failed and I never learned why, but worked af\ter a reboot or shutdown and power up. I wrote this HexStrip or HStrip to extract ASCII data out of Word Perfect or other files that got corrupt and could no longer be read. It is also good for scanning EXE and COM files in DOS to see if there is a virus that stores ASCII text when it infects without running the EXE or COM. I used it in Tradewars 2002 with the trader.dat to pull out all of his advice for playing the game in it. https://sourceforge.net/projects/hstrip/ https://sourceforge.net/projects/hstrip/ I had bought QEMM which helped as well, until the Windows 9X and Windows NT OS models put them out of business and Symantec bought out Quarterdeck and other companies. Also, I think B000:0000 to B700:0000 was the monochrome memory that could be used to load things into it as well if you never used it. I used to write DOS memory maps, until DOS came with MSD.exe that could show used and unused memory maps. Intel 8086/8088 had 640K of RAM, and 384K of reserved memory, that some of it can be used by EMS for paging to load things into it to free up the 640K.
dalf 10y ago
A lot of memories pop into my mind with this article including unrelated stuff as the first try of Linux, kernel 1.2.8, and the "how to setup the CDROM reader attached to soundcard ?" question. To go back to the subject, I remember to have used a "driver" to free up some additional memory, but I can't remember the name and how it worked. May be I found it reading Imphobia ? The name may starts with a R. There was the unreal mode / flat mode too : https://en.wikipedia.org/wiki/Unreal_mode https://en.wikipedia.org/wiki/Unreal_mode I've remember to have code a memory allocator for Turbo Pascal. With pure DOS (not Windows), it was easy to use after the setup.
Aardwolf 10y ago
Awesome article! Best read in a while. I wish it would continue to the state of things the next years, with DOS4GW, and Windows 95 and 98 still running on top of DOS. The article stops too early :)
ajnin 10y ago
Very interesting article. I hadn't realized that Microsoft strategy of developing their market not by the merits of they product but by lock-in to use business programs (and also games and such) went back so far. Also it's great to finally learn what "UMB" stands for in "DOS=HIGH,UMB". Never felt right to add that option without knowing its meaning :-).
cardiffspaceman 10y ago
I designed a game engine for a few games, implemented it on Windows 3.1, and assisted with its DOS implementation. The code running on this engine built equally conveniently for Windows or for DOS due to the design of the engine. The publisher wanted the games to launch and run decently if "mem/c" indicated 500K. This was what was typically available in a 1Meg machine if it had things like Netware installed. We achieved this in part with commercial source-licensed libraries and in part with Borland's VROOM overlay technology.

244 points by mwcampbell 10y ago

I attended a talk by Bill Gates several years back, where he stated that when IBM was developing the PC, he tried to convince them to base it on the MC68000, and that their decision to go with the 8088 set personal computing back a decade. As the article points out, though, there were a ton of 68000 machines that ultimately got left in the dust by the PC, so I wonder how it would have really turned out.

valuearb 10y ago
Intel turned out way better than Motorola (and everyone else) at increasing transistor density.
- pm90 10y ago
  Well, maybe that was because they had a lot more money to throw at R&D? Not saying either way, but it looks like this was the opportunity that really pushed Intel into the big league. To their credit, they used it wisely and kept making better chips.
  - LordKano 10y ago
    Intel's chips continued to advance after those designed by the AIM Alliance (Apple IBM Motorola) hit their ceiling, so I'm not sure it was just R&D budget. I was impressed by the performance of the PowerPC 970 but much sooner than expected, Intel's (and AMD's) lineup made it irrelevant.
  - astrodust 10y ago
    It's more like Intel had a CEO that understood what it took to win in the CPU business and Motorola ended up with a CEO that printed out his email and banned Macs from the company when they were one of the few licensees making Apple Mac clones and Apple was one of their biggest buyers of CPUs.
- Zaak 10y ago
  I would attribute that more to Intel's revenue than anything special about the company though.
- tyingq 10y ago
  They didn't really trounce all the RISC vendors until AMD showed them the way with x64. They wasted a lot of time on Itanium.
- Keyframe 10y ago
  As others have noted, Intel was in cash and drove on top of that mostly. Not to belittle Intel though. Motorola would do well, as evidenced by 88k and later PowerPC with Apple and IBM... but at that point in time it was already too little too late.
thelazydogsback 10y ago
Should have been the Z-8000! I would have liked to have seen Zilog/Motorola be the battle rather than Intel/Motorola. (But maybe that's just my TRS-80 bias showing...)
EliRivers 10y ago
As I recall (although it is only a recollection, so if someone's got better evidence than my unreliable memory I stand corrected), what drove the triumph of the PC was not that it contained an 8088, but the software available for it and the ease with which third parties could make compatible hardware (and indeed, clone the whole thing). I suspect (but cannot prove) that both of those could still have happened if they'd gone with the MC68000.
- gmiller123456 10y ago
  To cite "Triumph of the Nerds" again. There were several things that came together to make it possible. IBM's support for it was pretty essential, their bureaucracy being incompatible with a fast changing market leading to them outsource all of the components, and the simplicity of the system making it easy to reverse engineer.
  - digi_owl 10y ago
    In a sense the PC was a recreation of the Altair, but with extended IO features out of the box.
- Keyframe 10y ago
  I'd argue for 'open' hardware platform more than anything. Take a look at other personal computers of the time, within an order of (or two) magnitude price up or down, like Mac, Amiga, Atari, SUN, HP(UX), and SGI. They all had great(er) software and hardware and more advanced OS' and features, but got trumped quickly. On the software side, PC had business productivity from the start which could be used as an argument on the software front (Lotus 1-2-3, namely).
AnimalMuppet 10y ago
IIRC, a big part of the reason for choosing the 8088 was that Intel successfully generated some FUD about Motorola's ability to manufacture the 68000 in the quantity needed for the PC.
- Aloha 10y ago
  No. IBM had a second source requirement on procurement, Intel was willing to license or already has licensed the 8088 to be manufactured by someone else, and Motorola was not.
  - xenadu02 10y ago
    AMD was the second source BTW. The licensing agreement allows cross-sharing which is why Intel was able to adopt AMD64.
    - digi_owl 10y ago
      There were others as well. VIA is still around, while others have folded or merged (with Intel forbidding a license transfer).
gmiller123456 10y ago
And in "Triumph of the Nerds" Ballmer said working on OS/2 set them back 10 years too. So, I guess with these two setbacks together, the PC became un-invented.
digi_owl 10y ago
I seem to recall reading that the compatibility between 68k variants were less then stellar. Not sure if it was Filfre, in relation to the Amiga, or elsewhere.
- foobiekr 10y ago
  the 68k family did not maintain total binary compatibility for supervisor mode from chip to chip. this was a pain. the 24 bit addressing thing, yeah, that was a hazard as well.
ajross 10y ago
The 68k had its own list of dumb architectural mistakes, FWIW. Registers were 32 bits wide but load addresses were 24 bit -- the CPU just ignored the high 8 bits, which led to programmers trying to cheat and stuff things like tag bits into pointers, which then broke on the 68020 which expanded the address space. The hardware bus was async (!!!), meaning you had to arrange correct clock synchronization for every one of your peripherals independently. (c.f. "DTACK grounded", the classic 'zine of the 68k hobbyist). The exception handling was insanely complicated, and even then they got it wrong in the first version: faulting instructions couldn't be restarted, making the use of an MMU impossible even in principle. They fixed this (via dumping even more undocumented complexity onto the stack) in the 68010, which was essentially a "patch release" to the part that was needed by the Unix workstation community. It's true that starting the PC with a 32 bit flat address space would have saved headaches in the late 80's, and it's likely that the feature set in Win95 would have arrived a few years earlier. But on balance the mac and unix worlds had not less grief moving off of 68k.
- Ded7xSEoPKYNsDd 10y ago
  The 8086 also ignored high address bits, and Intel had to add workarounds for that in later CPUs: http://wiki.osdev.org/A20_Line http://wiki.osdev.org/A20_Line
  - ajross 10y ago
    That was a wraparound condition, sort of the opposite of ignored bits. Memory addressing on 8086 inherently adds two registers every time: the pointer and a segment register (which points to a 64k region of the 1M address space with a granularity of 16 bytes). The problem is what to do when the segment plus the address overflows. On the 20 bit original implementation, you just got the rolled-over address. (What you should have gotten was a fault of some kind, of course.) On the 286, the same addition would give a valid address in the second megabyte of memory, which isn't the same memory. So the PC/AT (not the CPU) had a compatibility switch wired that would force the 21st memory address line low in real mode for compatibility with apps that actually relied on the early behavior.
iconjack 10y ago
The story I heard at the time was that the IBM team did want to go with the 68000, but Motorola couldn't guarantee enough units.
- megablast 10y ago
  In those days you had to have a second source for your chips, in case something happens to you. AMD was Intel's seconds source, Motorola had none.

mikestew 10y ago

If one ever wondered why the original PCs were viewed as toys by professionals in the field, this article is a good explanation as to why. Imagine you go from, say, an IBM 370 mainframe which has had virtual memory, VMs, no-execute flags, and considerably more than 640K back in the 60s to...this morass just to use the memory you paid for (and pay you did, back then). Granted, PCs didn't cost a couple of million with a maintenance agreement, but that didn't make them any more useful for running your nightly batch jobs.

digi_owl 10y ago
As i learn of the mainframes of yesterday it feels like all the hoopla of _nix on x86 these days is basically rediscovering all those things mainframes did back then...
- mikestew 10y ago
  Well, an original PC cost, what, $5K back in the day? A new 3081 370-compatible from the early 80s was multiple millions (can't find hard prices quickly, so guessing). I'll bet the CPU in the mainframe alone cost multiples of an entire XT. Mainframe engineers had a little more breathing room when making their design decisions. So we can look at it one of two ways: those kids today, all excited about VMs and stuff we had in the 60s. Or, holy crap, I can do stuff on my phone that used to take a multi-million dollar mainframe.
- astrodust 10y ago
  Hypervisors are all the rage today but that's so 1970s in the mainframe world. Welcome to the party, kids.
  - digi_owl 10y ago
    Indeed. What I find most "puzzling" is the lack of acknowledgement of this in the business. Its like it is a whole new, almost magical, thing that the devs dreamed up. I wonder if it has to do with how the microcomputer world had to almost bootstrap itself without any input from the mainframe people, because the latter considered the micros little more than toys. And this continue into the present, as a large segment of the business is self taught. And by now even going to university will not expose you to mainframes, as they have largely been abandoned in favor of clusters.

thelazydogsback 10y ago

Should have some props in there for Topview, Desqview, and especially QNX...

zwieback 10y ago
Props from me. I loved Desqview, it worked great. I didn't really use high memory other than for Desqview and SmartDrv. Once the 386 came around it was so much easier, Watcom C++ was my favorite way to take advantage of my luxurious 16MB I could afford at the time.
- thelazydogsback 10y ago
  Compiling helloworld.c with one floppy and no hard drive on the original PC required one disk for each of the following: (1) source code, (2) cpp.exe, (3) cc1.exe, (4) cc2.exe, (5) lib manager (can't remember the name - something like "marion"?), (5) and the linker -- I think it was 8 floppy swaps total. It blows my mind that my first HD was 5 MB and cost $800. Also missing was the programming side things: LocalAlloc vs. GlobalAlloc, low-mem HWNDs, etc. - ug - don't miss that...
  - ThomaszKrueger 10y ago
    And the FAR PASCAL calls as well.
  - 13of40 10y ago
    I realized yesterday that for years I've been mentally measuring data by how many Amiga 3.5 inch disks it would take to store. Noticed this when I was patting myself on the back for getting the build output of the tool I'm working on down below ~60 disks.
  - digi_owl 10y ago
    At the same time the system felt much more controllable and understandable from a user POV. And I sometimes feel that Linux is going through a similar transition, at least on the user space level.

korethr 10y ago

This article is bringing back memories. Not just of fiddling with CONFIG.SYS and AUTOEXEC.BAT, but fiddling with the sound card too, as was mentioned in passing. As mentioned in the article, I did indeed feel a sense of triumph when I finally got Wing Commander: Privateer to run. As EMS was a kludge that sucked up high memory for its mappings, I eventually had a fancy CONFIG.SYS with different menu options for different memory setups, depending on which game I wanted to play. Good times.

spapas82 10y ago
Couldn't agree more! I was like 10 years old in the 90's (before Windows 95 on 1995) when all good games run on DOS. I had became an expert on how to edit config.sys and autoexec.bat to enable EMS or XMS or save a few KB off the 640 kb limit - some games needed more than 590 kb from base memory free even though they were also using extended memory! And of course you needed to know exactly your sound card configuration (IRQ number and COM port) and your video driver capabilities and memory size (I started with a hercules and moved over to a trident before getting a 3dfx voodoo). Yes, running a game then was much more difficult than double clicking an icon but it was worth it. The games of that era were great and you could aquire skills (persistance, attention to detail, thinking on finding solutions) useful for the rest of your life - if you were a kid at least!
- khedoros1 10y ago
  We're close to the same age. I remember that I had certain games with awesome boot disk creation utilities, and I knew which disks would help with which games. Although, those were always just the next step after running memmaker again, hoping that it would find just a little extra (but not really understanding what it was doing). And I remember being a little disappointed when a game only supported the PC Speaker or Adlib, but shrugging, and deciding to be grateful that I didn't have to worry about getting digital audio working too.
  - digi_owl 10y ago
    I think one game that gave me grief back then was Master of Magic. It needed lots of free memory, EMS, and those two plus sound was nigh impossible.

zwieback 10y ago

Shout out to Windows Real Mode, which had a built-in virtual memory manager that swapped out unused memory to disk. All of that required apps to participate, of course, but it could multi-task in the lower 640K.

LeoPanthera 10y ago
Astonishingly, Real Mode still exists even on 64-bit Intel chips, and is still the default mode. Booting a modern OS involves a whole stack of bootstraps to jump from Real Mode to Protected Mode to Long Mode. It's duct tape all the way down.
- digi_owl 10y ago
  That's one of the things I feel FOSS is largely underestimating, the amount of old code running in offices around the world. You can still run programs from the Windows 1.x-3.x era (win16) if you have a 32 bit Windows 10 install. You apparently need the 32 bit version because 64 and 16 bit modes are mutually exclusive (or some such).
  - poizan42 10y ago
    It's because Virtual 8086 mode is unavailable in long mode. So either you would have to switch the cpu in and out of long mode (which probably has a performance penalty and complicates the code), or use the more general purpose virtualization support (which may not be available), or just emulate everything. It not surprising that Microsoft just decided that it wasn't worth it.
- astrodust 10y ago
  It's a 16-bit CPU with 32-bit extensions running in 64-bit mode.
  - LeoPanthera 10y ago
    Prefix this with "It's a 64-bit CPU pretending to be..." and you've got it right.

jsnell 10y ago

It feels kind of embarrassing to admit that despite years of tweaking this stuff to get games to run as a kid, I never actually bothered to find out what the difference between EMS and XMS was. Or even know the basics of how they both worked. "It's just extra memory, right?". It's bizarre that the computer magazines I read (and obsessively reread) would not have run an article like this.

zerocrates 10y ago
> It's bizarre that the computer magazines I read (and obsessively reread) would not have run an article like this. The "Megamemory Explained" graphic used in this post comes from the Jan. 14, 1986 issue of PC Magazine, part of an article called "Enlarging the Dimensions of Memory." It doesn't cover XMS as the 386 was so new as to be effectively nonexistent at the time, but otherwise seems to be a pretty thorough explanation.
- polpo 10y ago
  And here's another article from 1993 in PC Magazine which goes into detail, and with a bit more accuracy than the original article for this HN discussion (for example, it explains how XMS works on the 286): https://books.google.com/books?id=gCfzPMoPJWgC&pg=PA302&lpg=PA302&dq=xms+loadall&source=bl&ots=rmlgK_Hia9&sig=skK-3_tKMmhbFteI4FgBgnYTUhc&hl=en&sa=X&ved=0ahUKEwjbgMq26aTTAhVdImMKHSnTACUQ6AEIMDAC#v=onepage&q=xms%20loadall&f=false https://books.google.com/books?id=gCfzPMoPJWgC&pg=PA302&lpg=...
  - flomo 10y ago
    Wow, that is the exact article where I learned this stuff from. (Funny how your memory gets jogged like that.) I was an Apple guy and a late comer to the PC world, and PC Magazine was pretty much a must-read back in the day. Lots of good technical content.
joakleaf 10y ago
As I recall: you could only access XMS memory by copying. So you had to _copy_ a memory block from above the 1MB barrier to the lower 1MB addressable space to read, and copy back up again to write. EMS was pageable. You could had up to four 16 KB pages below 1MB that were fully accessible, but you had to select which address above 1MB each of those four pages had to point to. So in short, XMS was inefficient, because you had to copy, and EMS was more efficient because you simply decided which part of the extended memory you wanted to map to lower memory. I think, EMS was emulated in real mode on the 80386 chip by using its virtual 8086 mode. This was not possible on the 80286, so the 80286 could only use XMS in real mode. I briefly developed using both EMS and XMS, and as I recall, XMS was somehow less painful to get up and running and generally work with, but the performance conscience part of me obviously favored EMS's paging mechanism. Fortunately, 32-bit memory came along quickly both in the form of Windows and DOS protected mode.

raarts 10y ago

The article mentions confusion. That's an understatement. Information was much harder to come by at the time, you had to rely on articles in computer magazines. Also many bugs existed in memory drivers, not to mention interoperability problems, due to programmers not understanding the issues. This brings back memories, but not particularly good ones.

ThomaszKrueger 10y ago

It should be noted that some level of multitasking was achieved with so-called TSRs (terminate and stay resident programs). My preferred utility of course was Sidekick.

guelo 10y ago

The original mistake was made by the IBM engineers that came up with that memory map. They reserved a few bytes at the beginning and then a bunch of bytes at the end. That really makes no sense. They could have avoided all the pain that followed by putting all the reserved space in a contiguous block at the beginning. Maybe they thought it was easier for application programmers to use smaller address numbers? Or maybe it was due to some hardware shortcut, which wouldn't be surprising considering they had already taken the shortcut of using the 8088 instead of 8086. This kind of story is repeated whenever temporary hacks turn into massive successes, for example Javascript's limitations that still haunt us today. If you dig down into these histories you almost always find that it's not the engineers' fault but shortsighted managers.

zwieback 10y ago
I thought it was because it's easier to decode a few upper address lines on the bus so each peripheral is cheaper and easier to build. If you put the hardware addresses in the lower address space you'd have to decode the entire address to see if the access is on your card. I think the real problem was that people didn't want to let go of DOS. OS/2 1.x was a fine OS, especially from 1.2 onward and it ran great on a 286.
- mschaef 10y ago
  OS/2 may have been fine in the abstract, but set in the context of the time, it left a lot to be desired. Not only did it require a bunch of extra (expensive) memory, it also required new the purchase of new software to take advantage of that memory. (Otherwise it was just a hobbled version of DOS via the compat. box.) Combine that with the $3K SDK cost and the deliberately incompatible PM, there were good reasons it was a hard sell.
  - Zardoz84 10y ago
    One of the big fails of OS/2 was the IBM never had the desire that it would ran on any PC clone. They priorize doing something similar what does Apple with OSX on lesser degree. In other words, there was few drivers for hardware that wasn't on a PS/2 computer. Add to the mix the non cheap SDK...

floatboth 10y ago

I'm really surprised that the DOS extenders weren't the first solution to appear…

mwcampbell 10y ago
If I understand the article correctly, DOS extenders weren't feasible until the 386, because the 286 couldn't switch out of protected mode and back to real mode except by doing a full reset.
- WalterBright 10y ago
  There were effective 286 DOS Extenders. Zortech included the Rational Systems 286 DOS Extender with the Zortech C++ compiler.
  - bni 10y ago
    After reading the article, I am really curious how these could work.
    - cardiffspaceman 10y ago
      We're talking protected mode. The segment register would be an index into a table of segments of memory and the segments would be implemented in your RAM, and all of them would be accessible "at once" modulo the fact that there were only a few segment registers. The DOS extender could hack DOS so that you could in some fashion call DOS through "INT 21h" and it would do something (emulation, call through glue code into real mode etc). The call might require a transition into and out of real mode, which would not be cheap. Sometimes the only way to call DOS was to use "low" memory that was directly accessible from real mode, and you'd need to use special routines instead of malloc/free to manage that memory. You'd still have to call DOS through a hack but the memory arguments of the call would not need to be rearranged within the extender.

psyc 10y ago

For the first decade or so that I was programming, the 640k barrier was as normal as air. Now I do back-of-envelope calculations that tell me a single data structure is 100MB, and I'm like, "Yeah that's fine."

avodonosov 10y ago

Intel could have allowed more memory in the real mode, instead of providing that only in protected mode incompatible with the existing software ecosystem.

polpo 10y ago

This article is a bit inaccurate about XMS. XMS works just fine on the 286; see the original spec [1]. This is done purely in real mode on the 286 with the the A20 line [2] which allows addressing a 64kB area above 1024MB, in combination with the the undocumented LOADALL instruction, which allows addressing even beyond that [3]. [1] http://www.phatcode.net/res/219/files/xms20.txt http://www.phatcode.net/res/219/files/xms20.txt [2] https://en.wikipedia.org/wiki/A20_line https://en.wikipedia.org/wiki/A20_line [3] https://retrocomputing.stackexchange.com/questions/1006/what-is-the-infamous-instruction-loadall-on-the-80286-and-what-was-it-used-for/1011 https://retrocomputing.stackexchange.com/questions/1006/what...

thought_alarm 10y ago

Great read. Are there technical reasons why Microsoft didn't release a Protected Mode version of MS-DOS in the 80s, or was it just a case of trying to push users and developers to OS/2 and Windows? It seems like such a no-brainer, especially since MS-DOS provided so few services to applications anyway. You have MS-DOS 8 and MS-DOS 16, and you let the user choose which version to boot into, or you automatically kick over to MS-DOS 16 when a Protected Mode app is launched. It seems a lot saner than forcing users to muck around in config.sys. That people were forced to deal with the memory limitations of the 8088 PC well into the 90s is just bananas.

stickfigure 10y ago
It's not quite that simple. DOS is not like what we think of as an OS today; more like some libraries that sit in RAM at known addresses plus a loader barely smart enough to transfer data from disk to RAM and start execution. All the intelligence is in the application program itself. And those programs were still stuck with 20-bit pointers. It wasn't just a question of rewriting the OS, it was also a question of rewriting all the application software. Which eventually happened.
- digi_owl 10y ago
  And why I half-jokingly consider unikernels "DOS in a can".
  - throwaway91111 10y ago
    Nothing bars unikernels from running their code in protected memory as the sole non-ring-0 proc.
JdeBP 10y ago
Microsoft did. It was simply inside 386 Enhanced Mode DOS+Windows. By the way, MS/PC-DOS provided quite a lengthy list of services to applications. Have a look at DOS parts of Ralf Brown's Interrupt List some time.

orbitingpluto 10y ago

Microsoft Mouse (software release 9.00) from 1993 was a coveted driver back in it's day. If I remember correctly I think it only took 2K of conventional memory and the rest shunted into upper memory. After discovering that on a BBS I rarely needed an alternative config.sys/autoexec.bat.

lordnacho 10y ago

The 640K thing precipitated the first program I ever wrote. If you can call it that. I had a bunch of games I wanted to play in the early/mid 1990s, including Wing Commander. Each one seemed to require it's own config.sys/autoexec.bat, so I wrote a menu type thing to choose the game and do the appropriate setup. The experience made me think about what else I could do by joining a few commands together. I wish the internet had been available to me then, because I would have made much faster progress if something like stackoverflow had existed.

AceJohnny2 10y ago
> because I would have made much faster progress if something like stackoverflow had existed. Kids these days have it easy! /s
- deleted 10y ago
  [deleted]
0xADEADBEE 10y ago
Couldn't agree more. I try not to think about it but if I'd have had the resources available to me back then that I have now, I would be orders of magnitude better. I built my first computer about 17 years ago but dial up was still a thing and I was discouraged from spending time on it so I just did html in the 30 minutes per day I was allowed. If I'd have found a REPL back then, I probably wouldn't feel so inadequate when discussing concepts with my friends at the big 4! It'll work out fine, but later than planned; the spectre of unemployability will start looming in a decade or so, which certainly motivates me!

Zardoz84 10y ago

I rememeber that I was very effective tunning the config.sys and autoexec.bat to grab the max conventional ram. If my memory don't fail, I think that I managed to get ~636-634KiB on my first PC (an AMD 386@40 with 4 MiB of RAM). I usually, launch memmaker, and then fine-tune the config.sys & autoexec.bat . country.sys ? doskey.sys ? ansi.sys ? Remove it! I need moar free conventional ram !

nvahalik 10y ago
That was my first thought—hmmm... memmaker.exe ought to take care of this.

supernintendo 10y ago

> "640 K ought to be enough for anybody." Bill Gates never actually said this [1]. There are those who might attribute this to the Mandela Effect. [1] https://www.wired.com/1997/01/did-gates-really-say-640k-is-enough-for-anyone/ https://www.wired.com/1997/01/did-gates-really-say-640k-is-e...

yuhong 10y ago

This reminds me of the OS/2 2.0 fiasco, which is so bad it is one of my favorite topics.

magoon 10y ago

So much time spent optimizing my system to provide as much "conventional memory" so I could run a performant BBS in 640K, with all the drivers and such. It's hard to imagine now.

orionblastar 10y ago

I used to work as a technician getting DOS/Windows 3.X and OS/2 2.X systems working. There was a program I used to identify expansion cards and get the ID number off of them. It could detect memory size as well, but that doesn't work in modern systems anymore. https://sourceforge.net/projects/gconf/ https://sourceforge.net/projects/gconf/ Had a VP with a WANG PC that used Microchannel, he needed Netware, AS/400, and the Wal-Mart client going at the same time and not cut into his 640K of DOS memory. There was a trick to it. First using card IDs I found the option floppies for his expansion cards from CompUServe (As The Internet/WWW was in infancy and our employer paid for CompUServe to research things) and I re-arranged the expansion card memory to leave a 64K area that was not used that DOS could load drivers into it to free up the main 640K memory. At the time Netware and AS/400 used DOS drivers, while OS/2 had OS/2 drivers that could access the memory beyond it. This was before Windows 95 (It was in beta test at the time). I had upgraded the VP to MS-DOS 6.22 used loadhigh and memmaker and other things and managed to get all three networks working with most of the 640K area free. No other tech had done things like that before. I studied programming in college, but this gconf tool I wrote had helped me out a lot. I wrote it in college and then modified it to be named whichnet so that it could read Arcnet or Starnet network cards and use the correct Netware driver for DOS on a boot floppy disk. Either by using the expansion card ID to detect the right card or by reading ROM memory and look for patterns or a signature. It had worked 99% of the time, and in the 1% it had failed and I never learned why, but worked af\ter a reboot or shutdown and power up. I wrote this HexStrip or HStrip to extract ASCII data out of Word Perfect or other files that got corrupt and could no longer be read. It is also good for scanning EXE and COM files in DOS to see if there is a virus that stores ASCII text when it infects without running the EXE or COM. I used it in Tradewars 2002 with the trader.dat to pull out all of his advice for playing the game in it. https://sourceforge.net/projects/hstrip/ https://sourceforge.net/projects/hstrip/ I had bought QEMM which helped as well, until the Windows 9X and Windows NT OS models put them out of business and Symantec bought out Quarterdeck and other companies. Also, I think B000:0000 to B700:0000 was the monochrome memory that could be used to load things into it as well if you never used it. I used to write DOS memory maps, until DOS came with MSD.exe that could show used and unused memory maps. Intel 8086/8088 had 640K of RAM, and 384K of reserved memory, that some of it can be used by EMS for paging to load things into it to free up the 640K.

dalf 10y ago

A lot of memories pop into my mind with this article including unrelated stuff as the first try of Linux, kernel 1.2.8, and the "how to setup the CDROM reader attached to soundcard ?" question. To go back to the subject, I remember to have used a "driver" to free up some additional memory, but I can't remember the name and how it worked. May be I found it reading Imphobia ? The name may starts with a R. There was the unreal mode / flat mode too : https://en.wikipedia.org/wiki/Unreal_mode https://en.wikipedia.org/wiki/Unreal_mode I've remember to have code a memory allocator for Turbo Pascal. With pure DOS (not Windows), it was easy to use after the setup.

Aardwolf 10y ago

Awesome article! Best read in a while. I wish it would continue to the state of things the next years, with DOS4GW, and Windows 95 and 98 still running on top of DOS. The article stops too early :)

ajnin 10y ago

Very interesting article. I hadn't realized that Microsoft strategy of developing their market not by the merits of they product but by lock-in to use business programs (and also games and such) went back so far. Also it's great to finally learn what "UMB" stands for in "DOS=HIGH,UMB". Never felt right to add that option without knowing its meaning :-).

cardiffspaceman 10y ago

I designed a game engine for a few games, implemented it on Windows 3.1, and assisted with its DOS implementation. The code running on this engine built equally conveniently for Windows or for DOS due to the design of the engine. The publisher wanted the games to launch and run decently if "mem/c" indicated 500K. This was what was typically available in a 1Meg machine if it had things like Netware installed. We achieved this in part with commercial source-licensed libraries and in part with Borland's VROOM overlay technology.