old processor architectures [was Re: The Strange Birth and Long Life of Unix - IEEE Spectrum]

[Scott Allen]

On 6 December 2011 23:28,  <phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org> wrote:
> Personally, I found programming in PDP-8 assembler a huge chore and never
> got the hang of it. The 6502 instruction set was a gift from god by
> comparison.

The company I started working for, back in the late '70's was founded
by a few people who used to work at IBM.

The head technical guy was used to working on IBM System/360 class
machines, but we were developing products based on the 8080 CPU. The
8080 based product was also suitable as a development machine. Rather
than create a development environment using 8080 code, he wrote a
System/360 instruction set emulator for the 8080 and then proceeded to
write an editor, 360 assembler, job control language, etc. in 360
assembly code. So we had an emulated System/360 running on an 8080
microcomputer.

Products that we sold that used an 8080 (or later Z80) CPU also ran
this emulator and much of the application code was written in Sys/360
assembler.

Some parts of the 8080 product applications ran native 8080 code,
which was created using an 8080 cross assembler written in Sys/360
assembly code. So we had an 8080 system emulating a Sys/360 which ran
a cross assembler to generate 8080 code.

My experience was similar to Peter's: I preferred working with 8080
assembler over Sys/360 assembler.

-- 
Scott
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