The main features of the Alto were a terrific combination of speed, parsimony, and architecture. -- Speed came from bipolar transistors. It had a 150ns microinstruction time. -- Parsimony allowed these to be economic enough for a 1972 personal computer/workstation (we eventually built almost 2000 of these).
-- Architecture allowed it to be very flexible without sacrificing speed. To just mention one great idea: it had 16 "zero-overhead" program counters and separate logic to decide which one would be used for the next microinstruction -- this allowed bottom level "virtual multicore" multitasking for system functions (running the display, disk, handling I/O, painting the screen, emulating VHLLs, etc. (The Lincoln Labs TX-2 on which Sketchpad was done, also had multiple program counters, etc.) So an Alto-2 exercise should try to think through the issues of speed, parsimony and architecture in today's world of possibilities! Cheers, Alan ________________________________ From: Jecel Assumpcao Jr. <[email protected]> To: Fundamentals of New Computing <[email protected]> Sent: Wed, May 25, 2011 6:57:51 PM Subject: Re: [fonc] Alto-2? Ian Piumarta wrote on Wed, 25 May 2011 21:20:24 -0400 > Dear Casey, > > > a) I want to play with software > > b) I want to play with FPGAs > > You could start with Thacker's 'Tiny Computer' (described from p.123 onwards > in http://piumarta.com/pov/points-of-view.pdf) and add/fix whatever you think >is > missing/broken. Great advice, see also http://projects.csail.mit.edu/beehive/ You might consider starting out with a simulator before moving on to FPGAs. See the example microprocessor in http://www.tkgate.org/ This tool is a lot of fun. Unfortunately, I'll only be able to post a proper reply on Friday (and can make comments on SiliconSqueak then). -- Jecel _______________________________________________ fonc mailing list [email protected] http://vpri.org/mailman/listinfo/fonc
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