On 2020-03-23 5:49 PM, Ray Jewhurst 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. >
Here's a decent start: https://people.cs.clemson.edu/~mark/uprog.html --Toby > Ray > > On Mon, Mar 23, 2020, 5:33 PM Clem Cole <cl...@ccc.com > <mailto:cl...@ccc.com>> wrote: > > > > On Mon, Mar 23, 2020 at 3:57 PM Johnny Billquist <b...@softjar.se > <mailto: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 ... 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 <mailto: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 > _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
