3 ms·
> At some point we should be able to do a VAX You mean a processor where all of the complex opcodes are implemented in loadable microcode?
by derleth 14y ago
> At some point we should be able to do a VAX
You mean a processor where all of the complex opcodes are implemented in loadable microcode?
- ChuckMcM 14y agoThat's the one! I happen to have what is a fairly complete collection of all of the 'chip' VAX cpus (for Qbus) starting with the KA610 (MicroVAX I), through the KA692 (VAX 4000/700a), and its fascinating to watch the architecture go from a nearly pure microcode implementation to a nearly pure 'gate' implementation. From the perspective of looking at the tradeoffs of microcode vs gates it is really an excellent tutorial on computer architecture.
- derleth 14y agoIf we want a microcoded architecture, I'd prefer the PDP-10, but that's me. How much more complex is a mostly-microcode VAX implementation compared to a MIPS? The point about being able to move stepwise up the hardware complexity ladder by progressively replacing microcode with gates is a really good one, though.
- MaysonL 14y ago> I'd prefer the PDP-10 yeah, or a Foonly...
- spc476 14y agoYou're thinking of the Perq (http://www.chiark.greenend.org.uk/~pmaydell/PERQ/ http://www.chiark.greenend.org.uk/~pmaydell/PERQ/). The VAX was probably implemented with microcode, but it wasn't that modifiable.