The Mick and Brick book is THE BEST and 100% applicable to the 2901-based 11/730 and KS discussions here. http://bitsavers.org/components/amd/Am2900/Mick_Bit-Slice_Microprocessor_Design_1980.pdf
> On Mar 23, 2020, at 5:49 PM, Ray Jewhurst <raywjewhu...@gmail.com> wrote: > > Slightly off topic, could someone explain more about what microcode is and > how it works? The fact that the CPU instructions are they themselves > programmed in seems unfathomable. > > Ray > >> On Mon, Mar 23, 2020, 5:33 PM Clem Cole <cl...@ccc.com> wrote: >> >> >>> On Mon, Mar 23, 2020 at 3:57 PM Johnny Billquist <b...@softjar.se> wrote: >>> The VAX-11/750 used 2901 though... >> 750 was made out of custom CMOS gate arrays. The main adder was analyzed as >> part of my thesis [long story - not for here, but a very clever circuit. I >> would later get to know the guy that did it]. Paul Gilbeau and Dick >> Monroe were the main microcoders on the 750. I'm pretty sure that Paul was >> also one of the 780 microcode folks. Very interesting guy. I used to say >> he had a worm's eye view of the world -- perfect for his job as lead >> microcoder; but trying to get up a level could be difficult. I've lost >> track of them both, although I still talk to Dave Cane a couple of times a >> year and I think he knows how to find most of the HW team. >> >> I'm fairly sure that the 750 used te BLISS based Micro2 tools as Tim >> suggested and as I said, we cloned them at Masscomp in C (which later it >> went west). Tim, you tell me, I thought the Masscomp version got sent to the >> Jupiter team, but I'm pretty sure it was used for Prism. I remember us >> getting a 'bug report' because VAX-11/C didn't like something BSD's yacc had >> generated at one of the Hatfield/McCoy parties. I remember changing what it >> was and email it the next day. >> >> FWIW: All of the Masscomp FP/AP and the DACP used that set of microcode >> tools since they were all AMD 29xx based. IIRC, Chuck Palmer overhauled >> the original hack we did for Paul and Dick because a few Masscomp customers >> wanted to write custom DACP microcode and originally it was not too easy. >> I probably have a manual for that still around and maybe even the tools. >> But, since I don't have a DACP on the MC500 I still have, I never bother >> scooping up the tools. >> >> Also, I know that there was an Intel 808x processor (85 I think) that >> shipped in the 750, but it was not an FEP. It was limited to running the >> cartridge tape controller. I don't remember how the console serial port was >> done (the 780 it was part of the FEP). The 750 microcode did the boot as >> someone else pointed out. I've forgotten how the microcode was loaded on a >> cold start. I thought there was something in a ROM/EPROM, but I've >> forgotten. I do know the cartridge tape unit was needed to update the >> microcode and that was the only way to do it. But I don't remember you need >> to have the tape on a cold reboot the like floppies on a 780, but I could >> have forgotten. >> _______________________________________________ >> Simh mailing list >> Simh@trailing-edge.com >> http://mailman.trailing-edge.com/mailman/listinfo/simh > _______________________________________________ > Simh mailing list > Simh@trailing-edge.com > http://mailman.trailing-edge.com/mailman/listinfo/simh
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