3 ms·

The real story here is that sometimes you start a project and don't really know exactly where you're going, as you get into it you start to understand both the

The real story here is that sometimes you start a project and don't really know exactly where you're going, as you get into it you start to understand both the problem and the answer you want much better - and then yes, you can rip a chunk out and replace it with something smaller and better And don't forget, these guys had to fit everything, including those -2000 lines of code (assembler code) into 64kbytes of ROM - there was intense pressure to make stuff smaller

mananaysiempre 3y ago
QuickDraw is mostly written in Pascal with critical loops in assembly[1,2]. I’m also not sure if it’s in actually in ROM or on the boot floppy. (Incidentally, Wikipedia tells me the Lisa’s ROM was 16K.) [1] https://computerhistory.org/blog/the-lisa-apples-most-influential-failure/ https://computerhistory.org/blog/the-lisa-apples-most-influe... [2] https://computerhistory.org/blog/macpaint-and-quickdraw-source-code/ https://computerhistory.org/blog/macpaint-and-quickdraw-sour...
- Taniwha 3y ago
  I think it started out in ROM, it has low core jump vectors so that portions can be replaced (rather than just the whole thing) I worked designing Mac graphics accelerators back in the day, we hooked them up by replacing bits of QD through these vectors. So over time rom fixes got made and some of it would have come off of disk If you follow that second link you'll find a zip file with quickdraw source in it, you'll find that while there is a little pascal (.p files) most of the core is assembler (.a files)
  - Taniwha 3y ago
    Also putting display core routines in ROM was important because RAM access was slower (because the display used 1/2 the RAM bandwidth)
    - bcrl 3y ago
      Good point. The Amiga did the same thing in the Amiga 500 and 2000. The Amiga 1000 would have if the operating system had been more stable at time of release. It also saved a significant chunk of RAM as the 1.x releases of AmigaOS used 256KB ROMs while 2.x on were 512KB ROMs.

mananaysiempre 3y ago

QuickDraw is mostly written in Pascal with critical loops in assembly[1,2]. I’m also not sure if it’s in actually in ROM or on the boot floppy. (Incidentally, Wikipedia tells me the Lisa’s ROM was 16K.) [1] https://computerhistory.org/blog/the-lisa-apples-most-influential-failure/ https://computerhistory.org/blog/the-lisa-apples-most-influe... [2] https://computerhistory.org/blog/macpaint-and-quickdraw-source-code/ https://computerhistory.org/blog/macpaint-and-quickdraw-sour...

Taniwha 3y ago
I think it started out in ROM, it has low core jump vectors so that portions can be replaced (rather than just the whole thing) I worked designing Mac graphics accelerators back in the day, we hooked them up by replacing bits of QD through these vectors. So over time rom fixes got made and some of it would have come off of disk If you follow that second link you'll find a zip file with quickdraw source in it, you'll find that while there is a little pascal (.p files) most of the core is assembler (.a files)
- Taniwha 3y ago
  Also putting display core routines in ROM was important because RAM access was slower (because the display used 1/2 the RAM bandwidth)
  - bcrl 3y ago
    Good point. The Amiga did the same thing in the Amiga 500 and 2000. The Amiga 1000 would have if the operating system had been more stable at time of release. It also saved a significant chunk of RAM as the 1.x releases of AmigaOS used 256KB ROMs while 2.x on were 512KB ROMs.