The VAX was the first 32-bit CPU from Digital Equipment, intended to replace the older 16-bit PDP-11. The first VAXen actually included a complete PDP-11 to boot the larger VAX, and provide diagnostics. (The same strategy was employed by DECs angriest competitor, Data General with their Nova + Eclipse MV)
The VAX is considered the ultimate CISC-processor, with instructions for loops and polynoms. Studies of what VAX instructions were actually used in programs finally led to the ideas of RISC-architectures.
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