Beneath Apple DOSWorth, Don.
Beneath Apple DOS
by Worth, Don. · first published 1981
9mentions
6recommended by
8HN commenters
2013–2026first – last mentioned
75% recommend25% neutral
Why HN recommends it
Low-level tour of how Apple DOS 3.3 organizes disks, tracks, and on-disk formats. It serves as a reference for understanding floppy drives and copy protection, and suits retrocomputing enthusiasts.
Summarised by Claude from recommending comments
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…because my theory at the time was that they modded the disk head to write the bit weakly so that it couldn't distinguish a one from a zero during readback. A friend at school had a copy of Don Worth's Beneath Apple DOS, which absolutely blew my teenage mind. Until reading that book, I didn't think that any single human could understand and clearly explain a complex system so thoroughly.
on “Weak bits floppy disc protection: an alternate origins story on 8-bit” ↗"Beneath Apple DOS" by Don Worth and Pieter Lechner was my bible back then. Reading this book absolutely blew my mind and opened up a world of possibilities, not mentioning a much more intimate knowledge of how copy protection…
on “Apple II DOS source code released by Computer History Museum” ↗This is spot on, that's exactly how I remember the scene back then. "Beneath Apple DOS" (and later ProDOS) were the cracker bibles back then. It's pretty much the only official documentation you could buy that described how the floppy drives work at the lowest levels. There was no internet…
on “Cracking BurgerTime, a 1982 game on a floppy disk” ↗Hmmm, whole article about people reverse engineering apple dos, and no mention of "Beneath Apple Dos"? That ended up being one of my apple ][ books that nearly fell apart.
on “Apple II DOS source code” ↗…didn't get through reading one and go "but what about..." only to discover a dark hole. There was a bit of that, but usually 3rd parties stepped up and wrote books to fill in obvious gaps. The whole "Beneath Apple DOS/PRODOS" series is an example of that. One only needs to spend about 10 mins on stack overflow to see that much of it is the blind leading the blind, where most of the answers are incomplete, biased,…
on “My New Old Apple IIe Computer” ↗Somewhere in my library I have a copy of "Beneath Apple DOS" which was a detailed documentation of how Apple DOS wss structured, on-disk formats, etc. It has been awhile but I recall being impressed at how clean and reusable the DOS was. An excellent book if you…
on “Apple’s $13k operating system (2013)” ↗These guys were geniuses when it came to making the Apple ][ do weird things. I spent a ridiculous amount of my childhood reading “Beneath Apple DOS”…
on “"Our programs are fun to use" – Beagle Bros” ↗…handwriting in them: [0] Nibble mag ... https://www.nibblemagazine.com/ [1] 6502 Software Gourmet Guide & Cookbook, Robert Findly ... https://www.amazon.com/6502-software-gourmet-guide-cookbook/... [2] Beneath Apple DOS, by Don Worth and Pieter Lechner ... https://www.amazon.com/Beneath-Apple-DOS-Don-Worth/dp/091298...
on “Ask HN: What was programming like before internet?” ↗I was twelve or thirteen, had a ][e and with a copy of Beneath Apple DOS and the reference manual, and cracked a lot of software for the challenge. I wrote my own nibble copier but me and my friends pooled our money and bought Copy ][+ and Locksmith, which worked better. My…
on “Cracking BurgerTime, a 1982 game on a floppy disk” ↗