Comments on: More computer meta-weirdness from Tom7

More computer meta-weirdness from Tom7

DoctorFedora — Mon, 03 Apr 2017 06:15:33 -0800

Tom7/SuckerPinch is back. This time, he's written a DOS executable that only uses printable bytes. Because he could.

By: leotrotsky

leotrotsky — Mon, 03 Apr 2017 06:49:59 -0800

I ...I need to sit down for a little bit. This is the computer equivalent of that book written without the letter 'e'. But harder and more clever.

By: Proofs and Refutations

Proofs and Refutations — Mon, 03 Apr 2017 06:56:59 -0800

It's absolutely essential to watch through to the end where he reveals just what his program actually does, it's a wonderful punchline to the absurdity of the whole project.

By: ST!NG

ST!NG — Mon, 03 Apr 2017 06:59:11 -0800

beautiful

By: Mr.Encyclopedia

Mr.Encyclopedia — Mon, 03 Apr 2017 07:06:55 -0800

This was a needlessly elaborate way to do that to me.

By: donio

donio — Mon, 03 Apr 2017 07:17:35 -0800

I have a faint memory of a 7-bit email safe encoding format that was also a self-extracting DOS .com file. Sort of like shar for DOS. I thought that it may have been boo/deboo but I see no sign of such a feature in the source code. Any ideas which format this may have been?

By: idiopath

idiopath — Mon, 03 Apr 2017 08:02:58 -0800

YOEO

By: Rock Steady

Rock Steady — Mon, 03 Apr 2017 08:37:20 -0800

"This fractal pattern occurs frequently in mathematics, computer science and Hyrule." spittake.exe

By: the antecedent of that pronoun

the antecedent of that pronoun — Mon, 03 Apr 2017 08:42:13 -0800

the famous "EICAR test file" is a printable ASCII string that is also a short, valid DOS ".com" file: wikipedia. There's a good analysis of the design goals of EICAR and how it works here, including its use of self modifying code.

By: kersplunk

kersplunk — Mon, 03 Apr 2017 08:46:18 -0800

cya!

By: range

range — Mon, 03 Apr 2017 08:56:57 -0800

Okay, so (a) that's amazing and this guy is my hero, possibly second only to the dude that figured out how to bootstrap a processor to an operating system starting with a (paper) notepad to write down octal instructions and a paper clip to manually short pins to write in data (I am paraphrasing, I just looked and can't track it down, does it ring a bell for anyone else?) (b) Is this the "You Suck at Cooking" guy? Or is it just someone with a near-perfect voice match and very very similar sense of humor? I wasn't sold until the final voice over but that section is a dead-on match to the YSAC voiceovers.

By: that girl

that girl — Mon, 03 Apr 2017 09:25:53 -0800

range: b) No. I am an expert in Tom7 and YSAC is not Tom7. Although I totally understand your confusion.

By: the Real Dan

the Real Dan — Mon, 03 Apr 2017 09:29:31 -0800

Dr. Tom's paper is on page 129. You don't have to read it, but you really should *look* at it. It's part of the .. inspired whimsy.

By: cortex

cortex — Mon, 03 Apr 2017 09:30:12 -0800

"This fractal pattern occurs frequently in mathematics, computer science and Hyrule." Yeah, I was delighted by both the Sierpinski cameo and the understated Triforce joke and paused just to come in here and make sure it got a callout.

By: Nonsteroidal Anti-Inflammatory Drug

Nonsteroidal Anti-Inflammatory Drug — Mon, 03 Apr 2017 09:40:50 -0800

This is the computer equivalent of that book written without the letter 'e'. Wouldn't it be more like writing a cookbook in Russian, but only using words made out of Cyrillic characters that look like Latin characters (such as Ve, which looks like B)? AND THEN the Russian book using only Latin characters also contains an English narrative of how you traveled the globe to gather the cookbook's recipes, because, why not, it's all Latin characters!

By: Nonsteroidal Anti-Inflammatory Drug

Nonsteroidal Anti-Inflammatory Drug — Mon, 03 Apr 2017 09:42:41 -0800

(also all of the recipes are for foods that look like animals)

By: Xyanthilous P. Harrierstick

Xyanthilous P. Harrierstick — Mon, 03 Apr 2017 10:36:30 -0800

Did anyone else cheer when he got to the bit about the timer interrupt vector? I feel he's potentially missing out on an opportunity to stage I/O for int21 in a polled manner, but not so much that I can spare the several months required to find out. And then, the serial port is also reachable via in/out port io calls; just like the sound card; so it's not like he can't talk to the world already. Anyway. Jaw-on-the-floor amazeballs.

By: jcreigh

jcreigh — Mon, 03 Apr 2017 10:41:14 -0800

Oh man, the part where he just deadpans that the "FI" in Intel's pseudo-code is a typo just killed me. Also, if you go look at the paper/executable itself, and scroll down to the end, he embedded a histogram of the character counts of the file inside the file itself.

By: range

range — Mon, 03 Apr 2017 11:28:18 -0800

Did anyone else cheer when he got to the bit about the timer interrupt vector? (raises hand) I had the same thought that there's totally got to be a way to do polled i/o using that timer interrupt and got about 3 thoughts down the chain before remembering I had kids that would miss me if I went down that particular rabbit hole too far. On the other hand, taking this paper as evidence I assume he had the exact same thought and then a second, much smarter thought (which I am not reaching) in which he discarded it. The deadpan throwaway humor is just so totally perfect; I had to rewind after FI-as-typo because I realized I'd missed about a minute while I was laughing.

By: Xyanthilous P. Harrierstick

Xyanthilous P. Harrierstick — Mon, 03 Apr 2017 11:38:48 -0800

On the other hand, taking this paper as evidence I assume he had the exact same thought and then a second, much smarter thought (which I am not reaching) in which he discarded it. Yeah. That second, much smarter thought probably happened some time after the first one, though. Like that it can't be done without violating the self-modifying code restriction, or something.

By: meinvt

meinvt — Mon, 03 Apr 2017 12:46:45 -0800

Okay, I love this. So many memories of mucking about with this stuff at various levels. For once a CS related approach where the 20 years I've spent ignoring the subject seem to hardly matter! Plus, one of my fond memories of our old XT was writing a program to make the thing play a tinny version of Maple Leaf Rag; I appreciate his output approach.

By: dbx

dbx — Mon, 03 Apr 2017 12:58:00 -0800

For those who are interested, I highly recommend reading the paper itself (linked above by jcreigh). It's got all the good stuff of the video, plus way more detail, plus you're literally reading the program and the author has a lot of fun with the self-referentiality of it. I have been transfixed by reading this paper for like 2 hours now (so much actual work to do...) and it's just astounding. There was a moment, like 2 pages in, where I suddenly realized "Oh wait, this text (which consists entirely of ASCII with no newline characters) is justified!!" So the level of meticulous care put into this work is stunning. I'm trying to think of a way to force people to read it, because I feel like reading this paper is an unmitigated good for a soul.

By: DoctorFedora

DoctorFedora — Mon, 03 Apr 2017 15:29:39 -0800

Not only is it justified, it's two columns separated by plaintext spaces

By: idiopath

idiopath — Mon, 03 Apr 2017 16:32:02 -0800

There are some other great papers in the pdf linked above.

Reviewer D Ratings: Absolutely great ratings, HUGE audience. Confidence: I guarantee you there's no problem. Believe me. The Philosophy Department's got great people. They love me over there. It's no CS department, but boy they've got a lot of computers. My nephew would love it over there. Will's a great guy, known him a long time, trustworthy, not like the media, believe me.

By: comealongpole

comealongpole — Mon, 03 Apr 2017 17:20:00 -0800

Had to set this aside for a clear half-hour of my own. Don't claim to grok everything, but something that always amazes me is how closely the simple "microcomputer" z80/6502 messing around I did in my youth is directly applicable to how "real" computers work. The stack grows down, you guys, the stack grows down!

By: equalpants

equalpants — Mon, 03 Apr 2017 21:14:02 -0800

Wow, this is pretty amazing.

By: equalpants

equalpants — Mon, 03 Apr 2017 22:29:05 -0800

...and it's even more amazing having finished the thing. I totally lost it at "Thank you for playing Wing Commander!"

By: acb

acb — Tue, 04 Apr 2017 07:27:31 -0800

AND THEN the Russian book using only Latin characters also contains an English narrative of how you traveled the globe to gather the cookbook's recipes, because, why not, it's all Latin characters! Except that the actual executable code is not constrained in any way other than being all printable characters. That example would require it to say something semi-meaningful and at least tangentially related to the program and/or the process of creating it, in (possibly ungrammatical and weirdly spelled but at least marginally comprehensible) English.

By: radwolf76

radwolf76 — Tue, 04 Apr 2017 10:36:14 -0800

II had the same thought that there's totally got to be a way to do polled i/o using that timer interrupt and got about 3 thoughts down the chain before remembering I had kids that would miss me if I went down that particular rabbit hole too far. On the other hand, taking this paper as evidence I assume he had the exact same thought and then a second, much smarter thought (which I am not reaching) in which he discarded it. He does go into specifics in the actual paper as to why that trick was single use only.

It is very tempting to use this trick to make other system calls through INT 0x21, or perhaps to jump to arbitrary addresses of our choosing! Sadly, there are two very serious issues: - When the processor triggers the illegal instruction interrupt, the return address that it pushes on the stack is the address of the illegal instruction itself, not the one that follows it. So when the interrupt handler returns, it simply executes another illegal instruction. - When the interrupt is triggered, it clears the interrupt flag (so that for example the timer interrupt doesn't fire while it's already running). Only a few instructions, which we don't have access to, can restore the interrupt flag. This means that we would only be able to do this once, and after we did, many things would stop working because interrupts would stop firing.

By: DynamiteToast

DynamiteToast — Fri, 21 Apr 2017 07:00:38 -0800

Another fun dispatch from SIGBOVIK, On The Turing Completeness of PowerPoint (SLYT, 5 minutes and very funny).