Comment by adolph
5 months ago
It is interesting to compare/contrast/augment this story with those from folklore.org
New team member Bud Tribble suggested that it should be able to take
advantage of the Lisa's powerful graphics routines by migrating to its
Motorola 68000, and by February 1981, Smith was able to duly redesign the
prototype for the more powerful CPU while maintaining its lower-cost 8-bit
data bus.
This new prototype expanded graphics to 384x256, allowed the use of more RAM,
and ran at 8 MHz, making the prototype noticeably faster than the 5 MHz Lisa
yet substantially cheaper.
From folklore.org:
The idea was what [Smith] called a "bus transformer" circuit, built out of
PAL chips, which adapted the 68000 to an 8 bit memory bus by exploiting the
fast "page mode" access mode of the RAMs. The new Macintosh, designed over
the Christmas break at the end of 1980, featured an 8 megahertz 68000, 64K of
RAM, and a 384 by 256 bit mapped display. It was 60% faster than the Lisa
(which used a 5 megahertz 68000) but a lot less expensive.
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