23 Sep
2013
23 Sep
'13
12:06 p.m.
From: derschjo at gmail.com
=20
Right, at first I thought it might be a simple custom CPU of some sort,=20
but looking at the schematics (and the *very* detailed explanations in=20
the service manual) made it clear that it's basically a huge state=20
machine for parsing command text.
=20
I find that interesting that it would not be considered a CPU.
After all, that is all a CPU does. It would seem that the only
difference was that most CPUs encrypt the instructions.
It sure sounds like a CPU to me. It is a state machine that executes based on decoding
input.
I'm not sure that the input has to be some special binary
code and can't be directly decoded text to qualify as
a CPU.
A device that reads ASCII-encoded instructions from memory and executes
them is a CPU. But that's not the HP1350.
Incidentally, it's also hard to distinguish between a 'microcoded control
system' and a 'state machine' in some cases. Or between a 'microcoded
processor execting a program' and a 'RISC processor running an
instruction interpretter that executes a program'
-tony