On 23-Mar-20 13:35, Robert Armstrong wrote: >> Timothe Litt <l...@ieee.org> wrote: >> KS10 ... The 8085 code is crammed into UV EPROMs. > Was all of the KS CFE code in EPROM?
Yes, it is. There are a couple of microwords in the CRAM that deal with console responses (single step, console interrupts for the serial lines). But that's it. The KS can, and does initiate some bus cycles to get an RH11 tape or disk to load a record into PDP-10 memory. That record contains the CRAM ucode. The 8080 reads it from -10 memory and load the CRAM. And once it's a PDP-10, the next stage of boot (again, a few instructions) loads the monitor bootstrap. The CSL has no dedicated mass storage - and that was an issue of reliability even more than cost. The other issue is that CSL didn't have a lot of space. At the time, you wouldn't put DRAM on an 8085. (And if you did, you needed yet another few chips of refresh controller, address decoders, etc.) SRAMs were small and expensive. And once you took up the space for an EPROM socket, you might as well make it big enough to hold everything... One nice thing about the KS is that it was very well documented. (Had to do something with the time while internal politics prevented its release before the 780...) There's a copy of the technical manual on bitsavers, which you can read for more entertainment. > On the 730 only a small kernel of 8085 code (about 2K as I remember) was in > ROM/EPROM and the rest of the 8085 memory was RAM. The first thing the 8085 > did at power on was to load the rest of the 8085 code from the TU58. That > made it possible to issue updates to the CFE code as well as the microcode. > > Bob > > > _______________________________________________ > Simh mailing list > Simh@trailing-edge.com > http://mailman.trailing-edge.com/mailman/listinfo/simh
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