[skrebbel]

Random drive-by nitpick:

> From the beginning of the development, id had requested from djgpp engineers that their DPMI client would be able to run on djgpp's DPMI server but also Windows 95 DPMI server.

I'm pretty sure that "DJGPP engineers" is just one guy, DJ Delorie. DJGPP was always open source so I bet he got some contributors, but if the rest of this sentence is true that "id has requested from djgpp engineers", it just means they asked the maker of an open source tool they used to please add a feature. I wonder whether they paid him for it or whether DJ just hacked it all in at id's request for kicks. His "about me" page suggests he does contracting so might be the latter.

DJGPP was spectacularly good back in the day. I didn't appreciate at the time what a monumental effort it must have been to port the entire GCC toolchain and runtime to DOS/Windows. Hats off to DJ Delorie!

[djdelorie]

Back then, DJGPP was a much bigger group, and most of the Quake kudos go to Charles Sandmann, author of cwsdpmi, who worked directly with Id to help them optimize their code for our environment.

[thatjoeoverthr]

Thank you for this work. It was my first C compiler in 1998. Y'all helped me on the mailing list and you even replied to my e-mails! I was 11 and this was insane to me.

[djdelorie]

You're welcome!

[jhgb]

I too need to thank you for the very first C compiler I ever had access to in 1999, after 10 years of having a book on C in my possession that I couldn't use until then.

[skrebbel]

Omg I’m totally starstruck now!

Purely out of curiosity, was that all a volunteer open source effort or was the entire DJGPP group acting as a consulting organization?

[djdelorie]

The DJGPP project and its contributors were 100% volunteer. I'm sure some of the contributors took advantage of their involvement to obtain consulting gigs on the side (I did ;) but DJGPP itself didn't involve any. The Quake work was a swap; we helped them with optimizing, and they helped us with near pointers. Win-win!

[xtracto]

Just passing by to thank you. As many others have mentioned, DJGPP was pivotal for my life. I compiled my first C/Allegro games in DJGPP back in the mid/late 90s.

And here you are!!

[hhhAndrew]

+1 DJGPP/Allegro key life experience on my parents Windows machine, thankyou!

[maybewhenthesun]

Amen to that!

I think I remember there was some communication between ID and Charles Sandmann about CWSDPMI, so even though it's worded a bit strange for an open source project there's probably some thruth in it?

Also a bit strange how the author is surprised about Quake running in a 'VM', apparently they don't really know about VM86 mode in x86 processors...

[db48x]

Is the author surprised by that, or did you just misread it? The only relevant quote on that page that I see is “It is impressive to see Quake run at full speed knowing that Windows 95 runs DOS executable in a virtual machine.”

He is perhaps surprised that it runs _at speed_ in the VM, not that it runs in the VM which he already knows about.

[maybewhenthesun]

I mean VM86 is not really a VM in the modern sense of the word. And the author doesn't seem to know.

[rasz]

That and the fact Quake doesnt run in VM85 mode, it explicitly runs in _protected_.

[maybewhenthesun]

That as well, yes.

[zoeysmithe]

I think if you're relatively young is hard to know computing history. Its oddly older than one thinks, even concepts that are seen as new. Its sometimes interesting to see people learn about BBS's which flourished 40 years ago.

[bombcar]

It's a bit surprising because this is the author of the DooM Black Book and they know the underpinnings pretty well.

However, the difference between a DOS VM under Windows 9x and a Windows command prompt and a w32 program started from DOS is all very esoteric and complicated (even Raymond Chen has been confused about implementation details at times).

[trollbridge]

DPMI clients don’t run in a VM, though. They’re just a normal task like any other task / process in Windows.

[toast0]

So... Win32 runs in virtual mode. In 2025, we don't think of that as a Virtual Machine, but it totally is. Hardware access is trapped by the CPU and processed by the OS/DPMI server.

[trollbridge]

It's not a virtual machine. There is no hardware machine that presents itself to function like a protected-mode ring 3 task on an 80286 or an 80386 functions. And the 286 and 386 both lacked a "virtual 286" and "virtual 386" mode (although it would have been almost-trivial for them to support it; Intel just decided not to, probably figuring it wasn't important).

Virtual 8086 mode, on the other hand, does behave exactly like a real 8086, which otherwise would have been very slow to implement on a real 386, and was either very slow on a 286 or impossible due to the 286 having some errata that prevented normal virtualisation techniques (the 286 had some non-restartable exceptions).

[fredoralive]

No, in 386 mode 3.x and 9x the System VM and other DPMI clients runs in protected mode.

Virtual 8086 mode, as its name somewhat suggests, only runs real mode code.

[oso2k]

Only if they never call DOS or the BIOS or execute a Real Mode Software Interrupt. When they do, they ask the DPMI server (which could be an OS like Windows 9x or CWSDPIM) to make the call on their behalf. In doing so, the DPMI server will temporarily enter into a VM86 Virtual Machine to do execute the Real Mode code being requested.

http://www.delorie.com/djgpp//doc/libc-2.02/libc_220.html

[trollbridge]

But that's not the DPMI client running in a VM. That's the host ending up running in a VM.

Note that in a machine with EMM386, the machine is normally running DOS inside an 8086 VM... and the only reason it would switch out of that VM is when you fire up a DPMI client.

[VogonPoetry]

VM in this usage means Virtual Memory - i.e. with page tables enabled. Two "processes" can use the same memory addresses and they will point to different physical memory. In Real Address mode every program has to use different memory addresses. The VM86 mode lets you to have several Real Mode programs running, but using Virtual Memory.

[oso2k]

VM does not mean Virtual Memory in this context. VM does mean Virtual Machine. When an OS/DPMI Server/Supervisor/Monitor provides an OS or program a virtual interface to HW interrupts, IO ports, SW interrupts, we say that OS or program is being executed in a Virtual Machine.

For things like Windows 3.x, 9x, OS/2, CWSDPMI, DOS/4G (DPMI & VCPI), Paging & Virtual Memory was an optional feature. In fact, CWSDPMI/djgpp programs had flags (using `CWSDPR0` or `CWSDPMI -s-` or programmatic calls) to disable Paging & Virtual Memory. Also, djgpp’s first DPMI server (a DOS extender called `go32`) didn’t support Virtual Memory either but could sub-execute Real Mode DOS programs in VM86 mode.

http://www.delorie.com/djgpp/v2faq/faq15_2.html

[VogonPoetry]

I agree that my comment about VM was imprecise and inaccurate.

I do dispute your assertion that virtual memory was "disabled". It isn't possible to use V86 mode (what the Intel Docs called it) without having a TSS, GDT, LDT and IDT set up. Being in protected mode is required. Mappings of virtual to real memory have to be present. Switching in and out of V86 mode happens from protected mode. Something has to manage the mappings or have set it up.

Intel's use of "virtual" for V86 mode was cursory - it could fail to work for actual 8086 code. This impacted Digital Research. And I admit my experiences are mostly from that side of the OS isle.

I did go back and re-read some of [0] to refresh some of my memory bitrot.

[0] https://www.ardent-tool.com/CPU/docs/Intel/386/manuals/23098...

[trollbridge]

Slight nitpick: you could run fire up V86 mode without any LDT entries.

It's also possible to run Virtual 8086 mode without paging enabled, and when in Virtual 8086 mode, the 386 doesn't care about what's in the LDT/GDT (unless an interrupt happens). In practice this is never done because the Virtual 8086 task would only be able to use the bottom 1MB of physical memory.

[trollbridge]

Slight nitpick: OS/2 2.x+ did not have a way to disable paging, although you could disable virtual memory in any version of OS/2 by simply setting MEMMAN=NOSWAP.

On Windows 3.x, paging and swapping was optional - if you started it in 286 ("standard") mode. On Windows 95, paging is not optional, and it's not optional in Windows 3.11 for Workgroups either.

[bluedino]

Would love to see some interviews etc with DJ if he's up for it

[ddtaylor]

Same. I only have experience from M.U.G.E.N fighting engine with respect to DJGPP.

[EGreg]

I remember back in the day using DJGPP (DJ Delorie) with the Allegro library (Shawn Hargreaves), building little games that compiled and ran on Windows and other OSes, and being part of the community.

You can still play the little game I made in under 10K for the Allegro SizeHack competition in 2000: https://web.archive.org/web/20250118231553/https://www.oocit...

Back then I was also writing a bunch of articles on game development: https://www.flipcode.com/archives/Theory_Practice-Issue_00_I...

Anyone on HN was active around that time? :) Fun time to be hacking!

[olau]

Yes. DJGPP and Allegro was a great help, and a big step up from the old Borland Turbo Pascal I started out with. I remember trying to rotate an image pixel by pixel in Pascal. Allegro simply had a function to do it. And yes, the mailing list was great - Shawn Hargreaves and the couple of people in the inner circle (I seem to remember someone called George) were simply awesome, helpful people.

I eventually installed Red Hat, started at university and lost most of my free time to study projects.

[EGreg]

George Foot :)

[krajzeg]

I was quite active in the Allegro community around that time, mostly on the allegro.cc forums - but I was still a 14-year old learning the ropes back then. Missed out on DJGPP, it was already MinGW under Windows for me.

I took part in a few of the later Speedhacks, around 2004-2005, I think?

Allegro will always have a warm place in my heart, and it was a formative experience that still informs how I like to work on games.

EDIT: Hah, actually found my first Speedhack [1]! Second place, not bad! Interestingly, the person who took first place (Rodrigo Braz Monteiro) is also a professional game developer now.

[1]: https://web.archive.org/web/20071101091657/http://speedhack....

[jasomill]

I was, but my application was less fun: porting Perl code from Windows NT to MS-DOS to integrate with software that required direct hardware access to a particular model of SCSI card.

Worked great, and saved a bunch of time vs writing a VDD to enable direct hardware access from NTVDM or a miniport driver from scratch.

IIRC, the underlying problem was that none of the NT drivers for any of the cards we'd tested were able to reliably allocate enough sufficiently contiguous memory to read tapes with unusually large (multi-megabyte) block sizes.

[ddtaylor]

I was on BlitzCoder.

[eknkc]

Completely off topic;

So I just took a look at DJ’s website and he has a college transcript there. Something looked interesting.

Apparently he passed a marksmanship PE course at the first year. Is that a thing in US? I don’t know, maybe its common and I have no idea. I’d love to have a marksmanship course while studying computer science though.

[simiones]

US colleges have a very open curriculum, where you have wide leeway in what classes you actually take, especially in the early years of study. If you're coming from more European-style universities, this is vastly different to the relatively rigid course set you'd take (with a few electives here and there).

[expressadmin]

MIT offers a Pirate Certificate: https://physicaleducationandwellness.mit.edu/about/pirate-ce...

[Cthulhu_]

I wouldn't be surprised if it's a pretty normal thing in a few countries or regions in the world. Marksmanship and archery are also olympic sports.

[0x457]

Yeah, in Russia even thought everything is decided for you once you've selected your major, PE classes still for you to choose. Competition to get in was crazy too, none of that "first come, first served" - swimming only accepted top N students, table tennis held a tournament style competition (I went there with two friends and I had to play against both of them).

US colleges still have far more options, though.

[le-mark]

It would be an easy “A” for a lot of people in the US!

[cardiffspaceman]

My college required its graduates to pass a minimal swimming test. Just enough swimming ability to give a potential rescuer some extra time to effect the rescue, rather than have us go straight to the bottom of the sea. We all took a test in the first week or so. Those who failed had to take a course and retake the test.

[kelnos]

As a sibling poster mentions, US universities often have a very open curriculum. At my university, I got PE credit for classical fencing!

The marching band could also count for PE credit. I believe you could only get credit for one semester for it, and my university required two semesters of PE, so I gave fencing a try, having never fenced before.

[toast0]

I needed one PE credit to get a degree from my community college. My school didn't offer marksmanship, but I would imagine it would fit into PE, archery certainly would and there's synergy. I took Table Tennis to graduate. I don't think my engineering school where I got my BS required Physical Education though.

[mortehu]

US colleges last one year longer, and the first year is more academically similar to the last year of high school in Europe.

[kbolino]

It's definitely not common. My US university required 2 physical education classes, but only if you were under 30 and hadn't served in the military. They may have offered marksmanship, but I just took running and soccer (aka football). The classes were graded pass-fail and didn't even count for academic credit.

[kevin_thibedeau]

My high school had some marksmanship trophy's in their case dating back to the 70s. Responsible gun ownership was a real thing when a sizable portion of the male population were veterans.

[stronglikedan]

We have myriad available "electives" that contribute towards our degrees. I have college credit for "bowling and billiards" and "canoeing and kayaking".

[marpstar]

I took an 8-week, 1-credit badminton course to fulfill my PE requirements. I wouldn't be surprised to find a marksmanship course.

[gpderetta]

It was great indeed. DJGPP is how I learned to to program.