7 ms·

What was the role of MS-DOS in Windows 95? (2007)

142 points by luu 10y ago

userbinator 10y ago
Much has been written on the system call interface in NT (INT 2E, later SYSENTER), but there is surprisingly little documented about the 9x system call interface. So I disassembled its kernel32.dll and looked at where the function calls went... they all eventually end up at a far call: "call far [BFFC9734]" with EAX containing what looks like the syscall number, arranged by major/minor code --- and some of the numbers look suspiciously like the same as for the original DOS INT21 services. BFFC9734 seems to be the "magic address" for this.(Googling "BFFC9734" yields results, but surprisingly, not "BFFC9734h", "0BFFC9734h", or "0xBFFC9734".) Here are some more references to that I found, if you're curious: http://xaknotdie.org/TopDevice/5/articles/z0mb009.htm http://xaknotdie.org/TopDevice/5/articles/z0mb009.htm (Russian) http://andrewl.dreamhosters.com/site_z0mbie/ntoskrnl.txt http://andrewl.dreamhosters.com/site_z0mbie/ntoskrnl.txt (English version of above)
- BipolarElsa 10y ago
  I still have Brian Eno's "Microsoft Sound" as my startup sound. Still the best they've ever released. Nothing tops that.
csours 10y ago
Reinstalling Windows: https://www.youtube.com/watch?v=dQuDk3z25Ko https://www.youtube.com/watch?v=dQuDk3z25Ko Sung to the tune of When I'm Cleaning Windows: https://www.youtube.com/watch?v=sfmAeijj5cM https://www.youtube.com/watch?v=sfmAeijj5cM
- Senji 10y ago
  Did you know you can BSOD Win10 as a host os running VirtualBox when you're installing Win98se as a guest-os. During the install(from an iso) it manages to bsod(kernel panic) the host OS itself. A workaround for me was copying the files from the iso to a vhd and runing the setup from a "harddrive" inside the vm instead of emulated cdrom.
bluedino 10y ago
It was a bit of a technical achievement that Windows 95 managed to continue working at all when people buggered it up with 16-bit Windows drivers, DOS drivers, and old DOS programs like SMARTDRV
- ebbv 10y ago
  It often wouldn't keep working. Win95/98/Me installs would regularly start throwing BSOD or just performing terribly and have to be reinstalled from scratch.
  - minxomat 10y ago
    I guess I'm in the 1% again. 95 was horrible, but ME or 2k never failed to install for me and even handled then-legacy drivers w/o any issues. Was there the occasional BSOD? Sure, but I experienced much more on my Windows 10 machines over the last few months.
    - ebbv 10y ago
      Win2k was a very different beast from 95/98/Me. I guess it depends how long you used Me for but my 95/98/Me machines regularly had to be reinstalled from scratch, usually about once every year or so. Whether my gaming machines or work machines.
      - raverbashing 10y ago
        98SE was much more stable than Me or 95 though
      - minxomat 10y ago
        I used my ME machine for office, some gaming (with some external peripherals) and some Q(uick)BASIC programming. I never had to reinstall it, having used it for at least 3 years basically every day. The 98 PCs were used in an SMB with older printers and cash registers. They worked great. 95 never managed to run for more than a month without some catastrophe.
uabstraction 10y ago
FWIW, I work in a machine shop with many CNC machine HMIs running on Windows 95, 98, NT, and 2000. Somehow, beyond all expectations, they just keep on working.
yuhong 10y ago
When I was discussing the OS/2 2.0 fiasco, I liked to mention how Win9x's dependence on DOS allowed Caldera to continue to sue MS.
johansch 10y ago
I kind of dislike the attitude Raymond is showing here, to be honest. Microsoft did a very poor job of disclosing these very relevant (at the time) facts to programmers back then. I guess they still hadn't really understood the power of having a well-documented/readily available platform. I know that I was hunting for information on this particular topic - just having gotten dial-up Internet access for the first time in the spring of 1995. (But hey, there were still a shining light compared to Creative Labs :) )
- hesdeadjim 10y ago
  It had to have been purely defensive to avoid people building even more assumptions on top of what was already a convoluted mess.
  - johansch 10y ago
    Yeah, it's quite easy to imagine that their marketing and PR teams overrode the technical documentation team on this matter.
ASipos 10y ago
If you want a full answer, check out Schulman's Unauthorized Windows 95 and its sorta-sequel, Pietrek's Windows 95 System Programming Secrets. It's a sprawling exploration of the insides of this OS with the goal of answering precisely this question.

142 points by luu 10y ago

Much has been written on the system call interface in NT (INT 2E, later SYSENTER), but there is surprisingly little documented about the 9x system call interface. So I disassembled its kernel32.dll and looked at where the function calls went... they all eventually end up at a far call: "call far [BFFC9734]" with EAX containing what looks like the syscall number, arranged by major/minor code --- and some of the numbers look suspiciously like the same as for the original DOS INT21 services. BFFC9734 seems to be the "magic address" for this.(Googling "BFFC9734" yields results, but surprisingly, not "BFFC9734h", "0BFFC9734h", or "0xBFFC9734".) Here are some more references to that I found, if you're curious: http://xaknotdie.org/TopDevice/5/articles/z0mb009.htm http://xaknotdie.org/TopDevice/5/articles/z0mb009.htm (Russian) http://andrewl.dreamhosters.com/site_z0mbie/ntoskrnl.txt http://andrewl.dreamhosters.com/site_z0mbie/ntoskrnl.txt (English version of above)

BipolarElsa 10y ago
I still have Brian Eno's "Microsoft Sound" as my startup sound. Still the best they've ever released. Nothing tops that.

csours 10y ago

Reinstalling Windows: https://www.youtube.com/watch?v=dQuDk3z25Ko https://www.youtube.com/watch?v=dQuDk3z25Ko Sung to the tune of When I'm Cleaning Windows: https://www.youtube.com/watch?v=sfmAeijj5cM https://www.youtube.com/watch?v=sfmAeijj5cM

Senji 10y ago
Did you know you can BSOD Win10 as a host os running VirtualBox when you're installing Win98se as a guest-os. During the install(from an iso) it manages to bsod(kernel panic) the host OS itself. A workaround for me was copying the files from the iso to a vhd and runing the setup from a "harddrive" inside the vm instead of emulated cdrom.

bluedino 10y ago

It was a bit of a technical achievement that Windows 95 managed to continue working at all when people buggered it up with 16-bit Windows drivers, DOS drivers, and old DOS programs like SMARTDRV

ebbv 10y ago
It often wouldn't keep working. Win95/98/Me installs would regularly start throwing BSOD or just performing terribly and have to be reinstalled from scratch.
- minxomat 10y ago
  I guess I'm in the 1% again. 95 was horrible, but ME or 2k never failed to install for me and even handled then-legacy drivers w/o any issues. Was there the occasional BSOD? Sure, but I experienced much more on my Windows 10 machines over the last few months.
  - ebbv 10y ago
    Win2k was a very different beast from 95/98/Me. I guess it depends how long you used Me for but my 95/98/Me machines regularly had to be reinstalled from scratch, usually about once every year or so. Whether my gaming machines or work machines.
    - raverbashing 10y ago
      98SE was much more stable than Me or 95 though
    - minxomat 10y ago
      I used my ME machine for office, some gaming (with some external peripherals) and some Q(uick)BASIC programming. I never had to reinstall it, having used it for at least 3 years basically every day. The 98 PCs were used in an SMB with older printers and cash registers. They worked great. 95 never managed to run for more than a month without some catastrophe.

uabstraction 10y ago

FWIW, I work in a machine shop with many CNC machine HMIs running on Windows 95, 98, NT, and 2000. Somehow, beyond all expectations, they just keep on working.

yuhong 10y ago

When I was discussing the OS/2 2.0 fiasco, I liked to mention how Win9x's dependence on DOS allowed Caldera to continue to sue MS.

johansch 10y ago

I kind of dislike the attitude Raymond is showing here, to be honest. Microsoft did a very poor job of disclosing these very relevant (at the time) facts to programmers back then. I guess they still hadn't really understood the power of having a well-documented/readily available platform. I know that I was hunting for information on this particular topic - just having gotten dial-up Internet access for the first time in the spring of 1995. (But hey, there were still a shining light compared to Creative Labs :) )

hesdeadjim 10y ago
It had to have been purely defensive to avoid people building even more assumptions on top of what was already a convoluted mess.
- johansch 10y ago
  Yeah, it's quite easy to imagine that their marketing and PR teams overrode the technical documentation team on this matter.

ASipos 10y ago

If you want a full answer, check out Schulman's Unauthorized Windows 95 and its sorta-sequel, Pietrek's Windows 95 System Programming Secrets. It's a sprawling exploration of the insides of this OS with the goal of answering precisely this question.