I wrote a Pong game in a 512-byte boot sector

79 points13 comments5 days ago
akshat666

Built this as a personal challenge. No OS, no drivers — just x86 assembly and BIOS. 512 bytes exactly. Boots in QEMU.

Run it: nasm -f bin pong.asm -o boot.bin qemu-system-x86_64 boot.bin

GitHub: https://github.com/akshat666/-bootponggame

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amiga386

"No operating system. [...] Just [...] BIOS". Hmm.

Out of interest, is there a difference in environment between running a COM executable for MS-DOS versus running a bootblock? I know there's the whole of MS-DOS, but a typical size-coded demo (http://www.sizecoding.org/wiki/DOS) will only use int 10h to switch mode, and that's it. Everything else is IO mapped (e.g. the keyboard) or memory mapped (e.g. screen memory). Could these equally run as a bootblock, and vice-versa?

One difference I know of is that DOS maintains an ever-increasing timer that it writes to 0:046C... is that available at bootblock execution time?

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kragen

Possibly relevant is hugi-compo round 3, the "Pong" compo: https://www.hugi.scene.org/compo/compoold.htm#compo3

I spent three days disassembling Guillermo Sais's 142-byte winner, which was challenging to understand. My notes may be of interest; they are in gsais-pong.md in http://canonical.org/~kragen/sw/pavnotes2.git/

I hope this is not interpreted as any kind of criticism. I would much rather be responsible for maintaining Joshi's code than Sais's. But I suspect that most people who are interested in either work will be interested in the other.

joenot443

This is cool!

BTW I checked out your Github and tried the link to your personal site - looks like the www prefix isn't working.

www.akshatjoshi.com fails but akshatjoshi.com works. Gotta fix those A records!

matsz

It's probably one of the best introductory projects to x86 assembly on bare metal.

More advanced than my attempt: https://github.com/mat-sz/pongloader

BTW: You could provide a live online demo using v86 - https://github.com/copy/v86

Barry-Perkins

Pong in 512 bytes — boot, play, amaze

mg794613

Tomorrow it's my turn to pretend to have written this!

110111011110

always facinated by these.

some ideas: - could try to add another player. just need to map 4 more keys. IO should be fine doing it the same way (dont think itd need thread or whatever) the io is super fast in the qemu scenario.

- rather than have this in the MBR. make an MBR where you can select this sector to load as next sector and jump, maybe even with ability to return. *you can then expose other games too if ud ever be bothered for snake or minesweeper :D

just some tinkering ideas. cool project and hats off. its always more tricky than it looks these things!

anthk

Now that I see this, I'd curious if something like Nethack 3.4.3 or Slashem could be rewritten in T3X0 and be playable under 286 machines:

https://t3x.org/t3x/0/

There's a working Rogue port for Minix2 under a 16 bit CPU (and for the Z Machine too, and GBA, and several others...), but I think even Hack 1.0.3 would be too big to fit under a 286 with 640k.

It would be a good start if Nethack 1.3d got working under CP/M for instance, rewritten with T3X0 and some ASM hacks for speeds...

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