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VAX was a heavily microcoded design, so there wasn't really "silicon level" implementation of VAX instructions themselves - the microcode decoded the instructio
by p_l 5y ago
VAX was a heavily microcoded design, so there wasn't really "silicon level" implementation of VAX instructions themselves - the microcode decoded the instructions and set inputs to execution units, and unlike some modern microcoded designs, there was much less hardwired implementation AFAIK
- twoodfin 5y agoAt least some VAX models supported user-supplied microcode and thus a customizable ISA. This could be used, for example, to implement a Prolog abstract machine directly on the CPU[1]. [1] http://hps.ece.utexas.edu/pub/gee_micro19.pdf http://hps.ece.utexas.edu/pub/gee_micro19.pdf