5 May
2025
5 May
'25
11:02 p.m.
On Mon, May 05, 2025 at 04:09:29PM +0100, David Wade via cctalk wrote:
I think "Microprogramming" as a technique
has been around as long as we have
had computers. Couldn't the setting up ENIAC to behave like a stored program
computer in 1948 be described as "Microprogramming"?
That's an interesting question, but I'd say yes. I base that
on the idea that microprogramming is essentially programming
one universal machine to emulate another universal machine
with the purpose of using the programming model of the second
machine as one that is more convenient than that of the
first. Of course, it doesn't look at all like the microprogramming
we're used to, but I'd say it still applies.
> The Zuse Z1 from 1936(!) was microcoded, too. It
implemented for example
> floating-point arithmetic and conversion instructions
> (binary<-->decimal).
>
> Christian
I'd add that we can go back even farther. Babbage included
a mechanism on the analytical engine for the more complex
operations that was effectively microcode. I was implemented
with a cylinder (referred to as a barrel) that you could
screw blocks into. A set of levers were pressed against
a line of block positions along the length of the cylinder
and the presence or absence of a block would determine
whether the connected mechanism is engaged. Then the cylinder
is turned one step and the process repeated. The whole
thing ends up being a lot like typical horizontal microcode.
BLS