What's Where in the Apple

What Hacker News says

1. sllabresFeb 2026
   I have seen the topic a bit late, but nevertheless:

   I have learned 6502 assembler (and assembler) in general with "6502 assembly language programming by Lance A. Leventhal" (1979) [1] and "Apple Machine Language by Don Inman & Kurt Inman" (1981) [2]

   For the 'internals' of the machine, I had "What's Where in the Apple: A Complete Guide to the Apple Computer by William F. Luebbert" (1985) amazon:[3]

   [1] https://archive.org/details/6502-assembly-language-programmi...

   [2] https://archive.org/details/a2-ml

   [3] https://www.amazon.de/Whats-Where-Apple-Complete-Computer/dp...

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2. waffletowerJan 2026
   I strongly recommend "What's Where in the Apple": https://archive.org/details/whatswhereinappl0000lueb I loved that book back in the day. Specific, directly addressable memory locations are mapped to system devices in a way that is quite foreign and Wild West when compared to modern computer architectures.
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3. derekjaJul 2022
   what’s where in the apple. https://libgen.is/book/index.php?md5=67D333F6D1B0AA52E261459...

   I also had that experience and credit the deep understanding of an early system with intuition in rapidly understanding modern systems.

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4. rbanffyJan 2022
   > it would be less than 1" of paper (remember green lined fanfold?)

   I had a book, an extremely useful one, "What's Where in the Apple II" which contained a full commented ROM disassembly with all known entry points, what their inputs were and where they stored their output. It was about 2 inches thick when printed. My copy (of course it was photocopied - it was almost impossible to get imported books in Brazil back then) had an extra inch from all the post-it notes, markers, paper notes and so on I added to it.

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5. analog31Jan 2026
   >>> When BIOS interfaces weren’t sufficient they hit the hardware directly - and even if they weren’t doing that, they’d end up depending on behavioural quirks of IBM’s BIOS implementation.

   This happened with the Apple II as well, and made it impossible for Apple to update their system. Even minor changes, from the Apple II to the IIe and IIc, broke some apps. And if an app broke, it was presumed to be the hardware maker's fault.

   There was a book entitled "what's where in the Apple II" that documented all known variable locations and entry points in the Apple ROM and DOS. For instance people would just branch directly into weird places in the ROM, or poke directly into memory.

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6. abktJan 2026
   Is the Apple II Reference Manual good for that ? Or anything specific to the Apple II, like "What's Where in the Apple" or "Understanding the Apple II" ?
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