The Atari 2600 Technical Wiki

rodneylives — Tue, 28 Jan 2025 15:00:00 +0000

There are quite a number of refreshing things about the Atari 2600 Technical Wiki. There’s its subtitle, “Woodgrain Wizardry,” which is excellent. Its dedication to a 47-year-old game console. There’s it being a wiki that isn’t being hosted on damnable ubiquitous Fandom. Its direct writing style, which gets right to the point of each page. It’s also not a Youtube video, which is sort of okay if you have a Premium account or a working adblocker, but a hellscape if you don’t. Its the kind of page Google Search de-prioritizes if you’re not doing a web-only search, and even if you do that, sometimes gets skipped over.

It is true, this one’s for hardcore geeks and programmers only. I love reading about stuff like how to do large 48-pixel graphic displays, useful for score readouts or title screens, even if I probably won’t ever use that information myself. Or on Bank Switching, which reveals that, since there’s nothing in the system’s tiny cartridges’ ROM space that indicates which bank switching scheme is being used, emulators scan through the executable image looking for signature bytes to determine when to map parts of it to the processor’s address space, and homebrew games try to give them appropriate hints so they’ll work smoothly.

There’s a page, Introduction to Processor Hardware, that gives us the surprising information that some EPROM chips, when used with the 2600, may act unpredictably when used in a dark room. That quality esoterica right there.

rodneylives

Reverse Engineering the 6502

rodneylives — Tue, 30 Apr 2024 14:00:00 +0000

This is a 52-minute talk from 2010, from the 27th Chaos Communication Congress in Berlin, Germany (the talk is in English), presented by Michael Steil of Visual 6502, which successfully reverse engineered the venerable 6502 microprocessor, a chip used, in one capacity or another, in one form, or another, in all the Apple, Commodore and Atari microcomputers, the BBC Micro, the Atari 5200, in a modified from the Atari 2600 the NES, and countless arcade games, as well as in other places.

The talk is intended for a technical audience… literally. When the speaker asks who in the audience has coded in assembly before, practically everyone raises their hands. It’s recognized that we at Set Side B veer wildly between the most surface-level populist material and in-depth treatments for those with gigantic capacities for technical discussion and the attention span of a Galapagos Giant Tortoise. We like to think this is charming, and will listen eagerly if you tell us that you agree.

Anyway, here is that talk. I already mentioned that it’s 53 minutes. If that’s too long, there’s a speed-up function on Youtube. If that’s too technical, well, I don’t know how to help there. Maybe a read through pagetable.com’s documentation on the 6502. Oops! I’ve made it worse, haven’t I. Well, if you like, you might console yourself that the 6502 is really a simple processor to learn to code in. I’ve done it myself! There’s no memory management, there’s only three general-purpose registers, the stack is fixed in place, and all opcodes are one byte. It’s so simple that an extremely motivated child could learn it. Guess how I know?

27c3: Reverse Engineering the MOS 6502 CPU (Youtube, 53 minutes)

Here’s a description of the talk from the conference web site.

rodneylives

atari2600 – Set Side B

The Atari 2600 Technical Wiki

Reverse Engineering the 6502