22 Feb
2012
22 Feb
'12
6:10 a.m.
Dave McGuire wrote:
Not the FIS, but the LSI-11 chipset itself, either
four or five
chips. It's the WD Pascal MicroEngine chipset, with its microcode
rewritten to execute the PDP-11 instruction set.
Other way around. The WD Pascal Microengine came about a few years
after the LSI-11 (1979 vs. February 1975). It was actually the third
"standard" use of that chipset, after the LSI-11 and the WD16 (very
nearly PDP-11 compatible, used in the Alpha Micro systems before they
switched to the 68K).
The chipset was specifically designed for the LSI-11. It is optimized
for instruction decode and dispatch for the PDP-11 instruction set, and
is somewhat less efficient for implementing a bytecode instruction set
like UCSD P-code.