Norbert Landsteiner

Great article. I was curious about the game mentioned towards the bottom:

> At M.I.T. next door to Draper, some of the undergraduates play a game called “Space War.” To play “Space War,” you need a television screen, a computer, and a working knowledge of Newtonian physics. The TV screen shows a planet surrounded by spaceships. Each player fires torpedos from his spaceship, aiming them according to the laws of orbital dynamics. The torpedos must destroy either another spaceship or the planet. The game is enhanced by programming the computer to include such factors as time warps, so that a spaceship can disappear “for years.”

Thanks to the magic of the internet, I found a few versions of the game (actually called "Spacewar!"[0]), both the original[1] without time-warp and the more advanced version described in the article which includes it[2]. However contrary to the article's description it seems only the ships follow Newtonian physics, the projectiles always travel in a straight line, and I wasn't able to blow up the star or planet you're orbiting, though perhaps a version with these features exists and I simply wasn't able to find it. Interestingly, the circular layout isn't just for the game, the screen of the PDP-1[3] Which ran it was circular because it was originally a radar screen!

[0]: https://en.wikipedia.org/wiki/Spacewar%21

[1]: https://spacewar.oversigma.com/

[2]: https://www.masswerk.at/spacewar/

[3]: https://en.wikipedia.org/wiki/PDP-1

It's just a small site that has been out there for some time. I kicked out any analytics for good some time ago, so I do not have any reliable data myself. There have been times with hyped content collecting millions of hits in a few days, but those have been years ago. (Then, this only resulted in offers for buying the domain, for, what I can only guess to be business of varying trustworthy.) I added a blog two years ago with rather infrequent post activity. The content is quite specialized and probably far from general interest. Ad revenue from a few Google adds sprinkled here and there is about nil. Currently, Google search stats indicates varying performance from 1 to 1.5 M impressions and about 20 to 30 K clicks at the beginning of the year and a rather steep decline towards the summer. (Only estimated pages with first impression are slightly up. I've actually no idea what these figures do indicate nowadays, whether there's anything noticeable about them or not.) Ironically, the mails started, when the performance was going down. (Full disclosure: https://www.masswerk.at/)

Though no one has done it yet, Alan Kay is convinced a modest Spacewar could be built cheap: “You can do motion with a couple of integrators. Heathkit has this l6-integrator analogue computer you can build as a kit for 700 bucks or something like that. You have to have two layers of integrators to get an inverse-square law, so you should be able to get gravity and orbits with that one. To make spaceship outlines and explosion patterns you need a few bits of digital memory. Two chips worth of register file should do it. I think electronics stores may carry the chips.

Funny that Atari's first game Computer Space was developed the year before the article went to press, with an old black-and-white TV and some cascading digital counter chips, similar to how PONG would later simulate ball motion. And the spaceship outlines were literally outlined on the circuit board with diodes: http://www.masswerk.at/rc2017/04/images/e02-computerspace-diodelayout.jpg

Emulators support nearly everything. I can even run a TI994a program on a PC, Mac, or Linux. If you can't run emulators on Mac that is sad news to me. Maybe bad example, it was technically 16 bit, but it was well over 30 years old. Here is a pet emulator: https://www.masswerk.at/pet/

Just the other day my brother told me he met a really talented graphics designer that still primarily uses some 25 year old sign design software. Never heard of it before, and don't remember the name.

We balk at having to pay monthly for software we bought over 10 years ago and even today we'd not miss any new features offered. Great artists (I'm not one of them) can produce great visuals. Limitation can be better for creativity than no restrictions for some anyway.

I'd guess it's "undocumented", not "undefined". Don't know how the situation is on x86, but on the Z80 there were indeed some slight differences in undocumented behaviour between CPU vendors, but those are so obscure that it hardly affected any real world code (they affected the undocumented flag bits 3 and 5, and their behaviour was only properly 'decoded' in the 2000's (https://github.com/floooh/emu-info/blob/master/z80/memptr_eng.txt).

The only CPU I know with actual 'undefined' behaviour is the 6502 for some of the undocumented/illegal opcodes which can yield different results based on things like current CPU temperature (see the ANE/XAA instruction description: https://www.masswerk.at/nowgobang/2021/6502-illegal-opcodes)

> Only documented 6507 instructions were disassembled, since we reasoned that use of undocumented instructions would have been rare, and this avoided having a number of data values being erroneously interpreted as instructions.

This assumption jumped out at me. The 2600 programmers were pulling every trick in the book to crunch code size down and squeeze every cycle they could out of that 6507. How well those illegal opcodes [0] might have been understood back at this time is another question. They were apparently used in NES games [1] but that console obviously came later.

[0] https://www.masswerk.at/nowgobang/2021/6502-illegal-opcodes

[1] https://www.nesdev.org/wiki/CPU_unofficial_opcodes