[Simh] Simh Digest, Vol 198, Issue 16

[Bob Supnik]

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.

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-request at trailing-edge.com wrote:
> Re: [Simh] pdp11 fails MAINDEC CPU test 14 D0NA