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
