21–26 of 26 posts
Two obscure features of the Lisa that weren't retained on the Mac (IIRC): Pixels on the Lisa were not square. Tall rectangular pixels made for better font rendering. The Lisa had virtual memory? Not sure about that, but there was a neat feature that trapped stack overflows. The OS could expand the stack with the overflow trap was triggered.
Apropos of nothing, these photos remind me of trying to join a "club" for the video game Pitfall (on Atari) which required sending proof of a 20,000 score by mailing them a Polaroid of your TV screen. EDIT: Wow! I guess it's a known thing (glad I didn't imagine it): https://www.gameinformer.com/b/features/archive/2013/10/26/a...
Two obscure features of the Lisa that weren't retained on the Mac (IIRC): Pixels on the Lisa were not square. Tall rectangular pixels made for better font rendering. The Lisa had virtual memory? Not sure about that, but there was a neat feature that trapped stack overflows. The OS could expand the stack with the overflow trap was triggered.
The Lisa had a base&bounds MMU (a bit like a pdp-11) not a full paging MMU - we ported pre-sysVr2 (ie pre paging) Unix to it
Is the idea that you couldn't demand page, but that there'd be memory protection of some kind through the MMU for the entire process by rewriting addresses?
I remember reading that some workstation vendors ran two 68k CPUs in parallel in order to make it possible to recover from a bus error. Until the 68010 was released with the fix for this.
Earlier quoted context omitted.
The Lisa had a base&bounds MMU (a bit like a pdp-11) not a full paging MMU - we ported pre-sysVr2 (ie pre paging) Unix to it
I need to read up on the Lisa MMU some more, it's interesting because my impression was that 68k in general was not friendly to these things as it was not possible to recover from a bus error. Is the idea that you couldn't demand page, but that there'd be memory protection of some kind through the MMU for the entire process by rewriting addresses? I remember reading that some workstation vendors ran two 68k CPUs in p…
For a traditional swapping kernel (ie anything prior to SVr2) the only time you ever needed to be able to recover from a page fault was when you did automatic stack extension, there was a simple solution to this, have the compiler emit a "tst n(sp)", or similar instruction at every subroutine entry - because it was an instruction without side effects the kernel could recognise it, extend the stack space (by enough extra to be able to do the next call, hence the 'n') and resume execution by faking the appropriate kernel stack frame
Wow those Polaroids are going on 42 years old. Wonder how they're preserved/archived. Incredible part of early Apple history, a lot of which was destroyed around the return of Steve Jobs to Apple in the late 90s.
> Incredible part of early Apple history, a lot of which was destroyed around the return of Steve Jobs to Apple in the late 90s. I'm curious why you think this! Apple donated their museum and historical collections to Stanford in late 1997, and given the comprehensive nature of the gift I'd be very surprised to hear of a Jobs-driven "purge" before that happened. https://news.stanford.edu/pr/97/971119apple.html
Really appreciate your correction here!
Earlier quoted context omitted.
> Incredible part of early Apple history, a lot of which was destroyed around the return of Steve Jobs to Apple in the late 90s. I'm curious why you think this! Apple donated their museum and historical collections to Stanford in late 1997, and given the comprehensive nature of the gift I'd be very surprised to hear of a Jobs-driven "purge" before that happened. https://news.stanford.edu/pr/97/971119apple.html
Oooo that's good info, thanks! I seem to recall reading it somewhere, perhaps as context after the publication of AppleDesign: https://www.amazon.com/Appledesign-Apple-Industrial-Design-G... Really appreciate your correction here!