<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">The Mick and Brick book is THE BEST and 100% applicable to the 2901-based 11/730 and KS discussions here. <a href="http://bitsavers.org/components/amd/Am2900/Mick_Bit-Slice_Microprocessor_Design_1980.pdf">http://bitsavers.org/components/amd/Am2900/Mick_Bit-Slice_Microprocessor_Design_1980.pdf</a><div><div dir="ltr"><br>On Mar 23, 2020, at 5:49 PM, Ray Jewhurst <<a href="mailto:raywjewhurst@gmail.com">raywjewhurst@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr"><div dir="auto">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. <div dir="auto"><br></div><div dir="auto">Ray </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Mar 23, 2020, 5:33 PM Clem Cole <<a href="mailto:clemc@ccc.com">clemc@ccc.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Mar 23, 2020 at 3:57 PM Johnny Billquist <<a href="mailto:bqt@softjar.se" target="_blank" rel="noreferrer">bqt@softjar.se</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">The VAX-11/750 used 2901 though...<br></blockquote><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif">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. </span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif">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. </span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif">FWIW: </span><span style="font-family:arial,helvetica,sans-serif"> All of the Masscomp FP/AP and the DACP used <span class="gmail_default" style="font-family:arial,helvetica,sans-serif">that set of microcode tools </span>since they were all AMD <span class="gmail_default" style="font-family:arial,helvetica,sans-serif">29xx </span>based. IIRC, Chuck Palmer overhauled the original hack we did for Paul and Dick because <span class="gmail_default" style="font-family:arial,helvetica,sans-serif">a few </span>Masscomp customers wanted to write <span class="gmail_default" style="font-family:arial,helvetica,sans-serif">custom </span>DACP microcode<span class="gmail_default" style="font-family:arial,helvetica,sans-serif"> and originally it was not too easy</span>. I probably have a manual for that still around and maybe even the tools. <span class="gmail_default" style="font-family:arial,helvetica,sans-serif">But, since</span> I don't have a DACP on the MC500 I still have, I never bother scooping up the tools.</span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></span></div><div><span class="gmail_default" style="font-family:arial,helvetica,sans-serif">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.</span></div></div></div>
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