2 ms·

When I was in high school, I hand-assembled my 6502 code. I’d write it longhand out on graph paper, then write down addresses in the leftmost column, opcodes in

by dhosek 4y ago

When I was in high school, I hand-assembled my 6502 code. I’d write it longhand out on graph paper, then write down addresses in the leftmost column, opcodes in the middle & finally I’d type in all the hex from the Apple Monitor. It was slow, painstaking and error-prone, but it made for clear thinking about how the program worked before I sat at the computer.

jacquesm 4y ago
It probably also really honed your ability to simulate a CPU in your head. That's invaluable when looking at code, to build up a mental model of what it really does (rather than what the comments say it does).
colanderman 4y ago
I did the same (after reverse-engineering the opcodes by filling memory with sequential bytes and listing the output) until I discovered that the Apple //e (and maybe others) included a built-in mini assembler: https://www.youtube.com/watch?v=yJp2TnKhnzY https://www.youtube.com/watch?v=yJp2TnKhnzY
- dhosek 4y ago
  The Mini Assembler was part of the Apple ][ ROM with Integer BASIC but not on the ][+ ROM with AppleSoft BASIC. I think I eventually got a floppy from someone at a math competition or something like that which had a loadable Integer BASIC image that could be loaded into the RAM of a 64K Apple ][+ or //e, but that was not long before I graduated high school and at a point where I was doing most of my programming on a VM/CMS system (and then later VAX/VMS).
  - colanderman 4y ago
    The //e "Enhanced" model (which I had) had the mini assembler built-in. [1] The monitor even had a shortcut to start it -- "!". (Had to Google to remember this bit of trivia again -- funnily enough turned up this [2] HN comment I replied to 9 years ago with nearly the exact same comment I made above.) [1] https://support.apple.com/kb/TA39083?locale=en_US&viewlocale=en_US https://support.apple.com/kb/TA39083?locale=en_US&viewlocale... [2] https://news.ycombinator.com/item?id=6200660 https://news.ycombinator.com/item?id=6200660
jdswain 4y ago
There’s a story about someone watching Woz entering hex into the computer directly to write a program, and every now and then he’d pause for a little. They asked him why and he said he was calculating the offset for a forward branch, which would mean he’d have to think of all the code up until the branch destination and count the bytes. Then he could carry on and enter those bytes.
- jacquesm 4y ago
  That's pretty amazing. I would do something similar but easier: invert the branch do a jmp [word] and then continue as though nothing changed. Then, afer you know the destination address fill it into [word]. That way you don't end up running out of memory (your own, not the computer's). But Woz's trick is far more impressive.

by dhosek 4y ago

jacquesm 4y ago

It probably also really honed your ability to simulate a CPU in your head. That's invaluable when looking at code, to build up a mental model of what it really does (rather than what the comments say it does).

colanderman 4y ago

I did the same (after reverse-engineering the opcodes by filling memory with sequential bytes and listing the output) until I discovered that the Apple //e (and maybe others) included a built-in mini assembler: https://www.youtube.com/watch?v=yJp2TnKhnzY https://www.youtube.com/watch?v=yJp2TnKhnzY

dhosek 4y ago
The Mini Assembler was part of the Apple ][ ROM with Integer BASIC but not on the ][+ ROM with AppleSoft BASIC. I think I eventually got a floppy from someone at a math competition or something like that which had a loadable Integer BASIC image that could be loaded into the RAM of a 64K Apple ][+ or //e, but that was not long before I graduated high school and at a point where I was doing most of my programming on a VM/CMS system (and then later VAX/VMS).
- colanderman 4y ago
  The //e "Enhanced" model (which I had) had the mini assembler built-in. [1] The monitor even had a shortcut to start it -- "!". (Had to Google to remember this bit of trivia again -- funnily enough turned up this [2] HN comment I replied to 9 years ago with nearly the exact same comment I made above.) [1] https://support.apple.com/kb/TA39083?locale=en_US&viewlocale=en_US https://support.apple.com/kb/TA39083?locale=en_US&viewlocale... [2] https://news.ycombinator.com/item?id=6200660 https://news.ycombinator.com/item?id=6200660

jdswain 4y ago

There’s a story about someone watching Woz entering hex into the computer directly to write a program, and every now and then he’d pause for a little. They asked him why and he said he was calculating the offset for a forward branch, which would mean he’d have to think of all the code up until the branch destination and count the bytes. Then he could carry on and enter those bytes.

jacquesm 4y ago
That's pretty amazing. I would do something similar but easier: invert the branch do a jmp [word] and then continue as though nothing changed. Then, afer you know the destination address fill it into [word]. That way you don't end up running out of memory (your own, not the computer's). But Woz's trick is far more impressive.