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The Apple Disk II Controller Card (2021)

64 points by stmw

by zellyn

1 subcomments

For those who don't know, the Disk II Controller Card is considered by some to be the invention that best demonstrates Woz's genius.
It's also a great early example of the massive win you can get by replacing hardware with software (and "software" -- in the form of a state transition table encoded in a small ROM).
It's also one of the reasons there were so many fascinating and weird copy protections for Apple II software: since so much of the behavior was in software on the computer, it was malleable. (Since it uses the CPU for tight timing loops, the Apple II couldn't really do much else while using the disk.) The write-ups by 4am on IA are fun reading if you're into this kind of thing: https://archive.org/details/apple_ii_library_4am
There are some fun projects to record disks at the level of magnetic flux transitions. I'm mostly familiar with https://applesaucefdc.com by the amazing John Keoni Morris, which came with a new file format too, and some lovely UI software.

by dhosek

1 subcomments

The great thing about the whole Apple ][ system was that it was sophisticated enough to actually do stuff but simple enough that a single person could understand it (largely because it was mostly the work of a single person). To this day, my mental model of how a computer works is the Apple ][.

by jonjacky

0 subcomment

Here's a simulation in Lisp:
https://josephoswald.nfshost.com/circuit-sim/woz-machine-hw-...

by jakzurr

0 subcomment

Awesome, awesome. My old copy of "Beneath Apple DOS" is still sitting on a shelf across the room - this brings the memories flooding back.

by sgerenser

0 subcomment

If this kind of stuff interests you, you might want to check into the upcoming “Designed in California” podcast about Apple’s history (still on kickstarter but I think the campaign is over): http://designed.fm. I’ve listened to a few of their preview episodes already, here’s the first one: https://www.youtube.com/watch?v=OsOVyuc1v_w&t=4s

by TMWNN

2 subcomments

As zellyn said, Disk II is pure genius writ large.
It's flabbergasting how good Woz's designs were. Almost on a whim, he with the Disk II did something no one anywhere in Silicon Valley—anywhere in the world—was doing. Forget about IBM, HP, Shugart, Tandon. Just within Commodore and Tandy, Apple's direct 1977 competitors, there were abundant human and engineering resources to come up with a fast, inexpensive, and reliable floppy drive and controller; Chuck Peddle at Commodore was certainly no average engineer. And yet, Commodore was still unable to do this in 1984.
Whether one believes in the reality of the existence of the "10X developer", it's hard not to see what Woz did between 1976 and 1978—Integer BASIC, Apple II color graphics, and Disk II—as proof that such a being can exist, even if (as I have written elsewhere) that brilliance straddled the line between optimized and overoptimized. <https://news.ycombinator.com/item?id=41685888>