Re: Why VAX Was the Ultimate CISC and Not RISC

On Sat, 8 Mar 2025 1:02:29 +0000, Lawrence D'Oliveiro wrote:

On Fri, 7 Mar 2025 16:57:31 -0600, BGB wrote:
>

Like, bitfield helpers were too weird/obscure, but hard-coding parts of
the CRC or stuff related to DES encryption and similar into the ISA is
fine...

>
I blame C. The fact that C does not have built-in constructs to make
convenient use of variable bitfields seems to be the main excuse for not
supporting them in hardware instruction sets.

Way back in 1983, John Perry of Bell Northern Research convinced me
to add the masker to the barrel shifter in Mc 88100, and I saw then
and there that it was an advancement in the state of "shift
instructions".
C notwithstanding.

And then in return, the lack of efficient support in hardware becomes an
excuse for not having such constructs in the higher-level language.

Same excuse as misaligned memory references--shortsightedness.