4 ms·

Analysis of Lisa Clascal source-code

62 points by soapdog 4y ago

actionfromafar 4y ago
Pascal code is yellow on blue background.
- unkeptbarista 4y ago
  I think it displayed correctly for me. Still I switched to reader mode for comfort, due to the small font size and narrow column.
- soapdog 4y ago
  Thats Turbo Pascal, right? Been there, still miss it.
  - actionfromafar 4y ago
    I still maintain that Borland's text IDEs are the best ever produced. If I could have it today (+ a language server) I'd switch in a heartbeat.
- pjmlp 4y ago
  Depends on which version. :)
- retrac 4y ago
  I got to take a computer science course in high school. My teacher was one of the best I've had; she had been educated in the subject with punch cards, on the other side of the Iron Curtain. In the first class, she informed us that we would not be using the computers in the lab for the first half of the year. Half of the class dropped the course after that. I did not, and it changed my life. Pascal for me will always be blue on a whiteboard, semicolons optional.
Someone 4y ago
FTA: Just like Macintosh, Lisa has a Memory Manager whose heap is largely organized in terms of relocatable blocks referenced by handles rather than fixed blocks referenced by pointers […] What I find interesting is that, unlike the Memory Manager on Macintosh, I’ve not seen any references to locking handles so they don’t move during operations. I’m not sure that is correct. The Lisa had a MMU (http://bitsavers.org/pdf/apple/lisa/development_history/articles/Daniels_-_The_Architecture_of_the_Lisa_Personal_Computer_198403.pdf http://bitsavers.org/pdf/apple/lisa/development_history/arti...), and swapped data into and out of RAM, and data may have moved to different addresses when swapped out and swapped in again.
- dfox 4y ago
  The MMU is limited by the fact that it is bolted onto MC68000 which nominally does not support MMU in todays sense. The article you linked says that while code was on demand swapped ("paged" in UNIX terms) by OS (which they "empirically determined" to be possible on the CPU), data segments had to be swapped for process as a whole (with the process having ability to mark some of them as not needed at the time). This probably means that caring about how the memory model works was mostly opt-in for the user code. Original Macintosh does not have any kind of MMU and emulates this through software, which enables one to have "half-dereferenced segments" and thus requires segment locking.
  - rjsw 4y ago
    The Lisa could run UNIX, unlike the original Macintosh.
    - tablespoon 4y ago
      https://en.wikipedia.org/wiki/Apple_Lisa#Third-party_software https://en.wikipedia.org/wiki/Apple_Lisa#Third-party_softwar...: > For most of its lifetime, the Lisa never went beyond the original seven applications that Apple had deemed enough to "do everything",[citation needed] although UniPress Software did offer UNIX System III for $495.[32] > The company known as the Santa Cruz Operation (SCO) offered Microsoft XENIX (version 3), a UNIX-like command-line operating system, for the Lisa 2 — and the Multiplan spreadsheet (version 2.1) that ran on it.[33]

62 points by soapdog 4y ago

actionfromafar 4y ago

Pascal code is yellow on blue background.

unkeptbarista 4y ago
I think it displayed correctly for me. Still I switched to reader mode for comfort, due to the small font size and narrow column.
soapdog 4y ago
Thats Turbo Pascal, right? Been there, still miss it.
- actionfromafar 4y ago
  I still maintain that Borland's text IDEs are the best ever produced. If I could have it today (+ a language server) I'd switch in a heartbeat.
pjmlp 4y ago
Depends on which version. :)
retrac 4y ago
I got to take a computer science course in high school. My teacher was one of the best I've had; she had been educated in the subject with punch cards, on the other side of the Iron Curtain. In the first class, she informed us that we would not be using the computers in the lab for the first half of the year. Half of the class dropped the course after that. I did not, and it changed my life. Pascal for me will always be blue on a whiteboard, semicolons optional.

Someone 4y ago

FTA: Just like Macintosh, Lisa has a Memory Manager whose heap is largely organized in terms of relocatable blocks referenced by handles rather than fixed blocks referenced by pointers […] What I find interesting is that, unlike the Memory Manager on Macintosh, I’ve not seen any references to locking handles so they don’t move during operations. I’m not sure that is correct. The Lisa had a MMU (http://bitsavers.org/pdf/apple/lisa/development_history/articles/Daniels_-_The_Architecture_of_the_Lisa_Personal_Computer_198403.pdf http://bitsavers.org/pdf/apple/lisa/development_history/arti...), and swapped data into and out of RAM, and data may have moved to different addresses when swapped out and swapped in again.

dfox 4y ago
The MMU is limited by the fact that it is bolted onto MC68000 which nominally does not support MMU in todays sense. The article you linked says that while code was on demand swapped ("paged" in UNIX terms) by OS (which they "empirically determined" to be possible on the CPU), data segments had to be swapped for process as a whole (with the process having ability to mark some of them as not needed at the time). This probably means that caring about how the memory model works was mostly opt-in for the user code. Original Macintosh does not have any kind of MMU and emulates this through software, which enables one to have "half-dereferenced segments" and thus requires segment locking.
- rjsw 4y ago
  The Lisa could run UNIX, unlike the original Macintosh.
  - tablespoon 4y ago
    https://en.wikipedia.org/wiki/Apple_Lisa#Third-party_software https://en.wikipedia.org/wiki/Apple_Lisa#Third-party_softwar...: > For most of its lifetime, the Lisa never went beyond the original seven applications that Apple had deemed enough to "do everything",[citation needed] although UniPress Software did offer UNIX System III for $495.[32] > The company known as the Santa Cruz Operation (SCO) offered Microsoft XENIX (version 3), a UNIX-like command-line operating system, for the Lisa 2 — and the Multiplan spreadsheet (version 2.1) that ran on it.[33]