On 7/9/2020 6:25 PM, Bob Supnik wrote:
Yes, the PDP11 Architecture Handbook was a post-facto effort. The J11 was
finished; DEC did not intend to do another PDP11 processor. (I wrote a spec
for one, primarily as an exercise in trying to do a different microcode
structure than the PLA/ROM of the LSI11/F11/J11, but I lost it.) The only
formal part of the PDP11 architecture was the Commercial Instruction Set
extension, DEC STD 168, which was only implemented by the F11 and the 11/44.
AND the PDP-11/74 CIS option, I might add. Fully implemented, never sold.
It made Cobol run faster on the 11/74 than the 11/780 and marketing didn't like
that.
So it was shelved after we finished implementing it.
Don North
DEC 1975-1982
Variances in the PDP11 architecture were the driving force behind the
precision of the VAX architecture effort; and the problems in how floating
point was implemented were the driving force behind Mary Payne's relentless
efforts to make VAX floating point "good to the last bit," as she put it.
/Bob
On 7/9/2020 8:55 PM, simh-requ...@trailing-edge.com wrote:
Re: [Simh] pdp11 fails MAINDEC CPU test 14 D0NA
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Don North
AK6DN
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