21 Feb
2012
21 Feb
'12
10:25 p.m.
On 02/22/2012 01:10 AM, Eric Smith wrote:
Dave McGuire wrote:
Was it really?? Wow, how very embarrassing. I stand corrected. And
to think that bit of misinformation has been rattling around in my head
since the 11/73 (not /03) was a current machine!
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.
I read somewhere that it's actually an 8-bit data path, which always
seemed odd to me. Very interesting stuff. Is the chipset fully
documented anywhere?
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA