[COFF] [TUHS] Re: history of machine code translation, as mental architecture models

[John R Levine]

On Wed, 10 Jul 2024, Dan Cross wrote:
>< [[ Knuth described instruction by instruction simulation ]]
> Sure.  But we're trying to date the topic here; my point is that
> JITing was well known, and simulation was similarly well known; we
> know when work on those books started; it doesn't seem that odd to me
> that combining the two would be known around that time as well.

Simulators that interpreted a pseudo-machine code date from the early 
1950s.  They were popular before compilers existed.  Fortran and 
Flow-matic arrived in 1954, translating languages that were somewhat 
familiar to people into machine code, mathematical formulas for Fortran, 
business English for Flow-matic.  But it would be rather a stretch to 
assert that anyone was doing machine code translation in 1954.  It was a 
while until enough machine code existed for it to be worth thinking about, 
and the jump from tranlating from human-ish languages to translating from 
machine languages was likely far less obvious at the time than it is in 
retrosoect.

On the other hand, there was UNCOL.  In the 1950s people quckly realized 
that building a compiler for every language for every machine would be a 
lot of work, particularly in an era when there was such extreme variation 
in machine architecture.  So someone came up with UNCOL which was supposed 
to be a UNiversal Computer Oriented Language, or what we would call a 
universal intermediate language.  All of the compilers would translate the 
original language to UNCOL, and there wold be an UNCOL to machine language 
translator for each machine.  This reduced the NxM compiler problem to N+M 
if it worked, which of course it didn't because the languages and the 
machines were both too varied.  But UNCOL to machine code is in the same 
ballpark as machine to machine.

CACM articles on UNCOL here:

https://dl.acm.org/doi/10.1145/368892.368915

https://dl.acm.org/doi/10.1145/368919.3165711

I would still love to hear if there are any actual reports or papers or 
anecdotes of people doing machine code translation before the 1967 one 
that started this discussion.

R's,
John