[comp.arch] RPM-40, Transputer PREFIX, HP auto-shifted registers

mac3n@babbage.acc.virginia.edu (Alex Colvin) (02/29/88)

> Prefix instructions in the GE RPM-40

>The HP Precision Architecture provides for these kinds of operations by its
>Shift and Add instructions.  There is a pre-shifter before one of the
>inputs to the CPU.  It allows for one of the operands to be pre-shifted by
>upto 3 bits before an addition happens.

aren't these pretty much the same?
in the former case a PREFIX is folowed by an ordinary LOAD register (or PUSH).
in the latter case an ordinary LOAD register is followed by a SHAD.

it seems that the SHAD avoids the need for a special context after PREFIX.
maybe it should be called SUFFIX.
it also has other uses.