> The VAX-11/730 would have to have the microcode on TU58, as that is the > console media. Quite possible that it actually do load the microcode > from there at power up. I've heard that those machine were slow in so > many ways... :-)
The 11/730 has no microcode ROM as far as I can see. However part of the instruction decoding is done in hardware, so implementing a totally different instruction set would be inefficient The craziest thing I have found in the 11/730 is that the control store is dynamic RAM (lots of 16K*1 chips). Every few milliseconds the CPU is halted while the control store is refreshed. There is space for 4K more of control store (1K of that is fitted if you have the integrated disk controller or floating point board) which is SRAM. Quite why the whole lot isn't SRAM is beyond me. -tony