[TUHS] machine code translation,as mental architecture models

[Marc Donner]

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 at ccc.com> wrote:

>
>
> On Wed, Jul 10, 2024 at 3:23 PM Marc Donner <marc.donner at 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
>
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