11 Jul
2024
11 Jul
'24
2:04 a.m.
Picky, picky, Clem.
Given the dramatic differences in I/O architecture, interrupt handling, and
virtual memory between s370 and Power PC, it makes little sense to try to
translate system code this way.
On Wed, Jul 10, 2024, 15:39 Clem Cole <clemc(a)ccc.com> wrote:
On Wed, Jul 10, 2024 at 3:23 PM Marc Donner <marc.donner(a)gmail.com> wrote:
I can not imagine trying to translate system code
in this way.
Marc, you are better than that - proof by lack of imagination is not
very effective😘
Seriously, the "VAX Compiler" that Paul describes made a great deal of
sense to the VMS team when it was developed. It's all about *economics*,
not technical purity. And solution actually worked really well; as Paul
points out, it lived for many different ISAs that followed VAX at DEC and
now VSi.
What I always was amazed by was the Cutler use assembler in the first place
since DEC had production quality BLISS compilers. But as Dave Cane
[VAX750 lead] once put it, it was the world's greatest assembler machine.
Dave (famously) hated BLISS but was one heck of an assembly programmer.
VMS both at the kernel and systems level, was (is) in assembler, so
treating the VAX as a HLL and "compiling" to a new ISA was solid economics.
ᐧ