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Comment by kazinator | Hacker News Reader

It's a discrete CPU. This is how processors were made before microprocessors. Before 1970, we had discrete component mainframe machines, in fact running at multi-MHz speeds (e.g. CDC 6600).

https://en.wikipedia.org/wiki/CDC_6600

60 bit, 10 MHz processor, introduced in 1964.

Article says that was 10 times faster than other contemporary machines; but that still leaves those at around a solid megahertz.

Discrete logic circuits can be fast because they have a lot of area over which to dissipate heat and can guzzle current.

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The main issue isn't the CPU as such, it's memory. You can reasonably make a usable CPU using relays even, but a non-trivial amount of memory takes up sooo much space.

I learned this in Minecraft. I’d wired up ttls in college for intro to ee for cs majors, which was fun. But ram was a beast. I guess I’ll build another tower and upgrade to a full 1k.

Ram takes so much space.

The Virtual Circuit Board game/sandbox at Steam offers an external memory, presumably for this reason.

I remember a Minecraft mod from way back that let you do "modular" redstone, going "into" blocks to build redstone inside them, which you could then reuse as a single block. I wonder if it's been updated.

Discrete logic circuits can be fast because they have a lot of area over which to dissipate heat and can guzzle current.

Moreover, most of them used either ECL or TTL, which are logic families much faster than P/N/CMOS. This being a transistor-level replica of an NMOS 6502, it can't go much faster.

> Discrete logic circuits can be fast because they have a lot of area over which to dissipate heat and can guzzle current.

... but not too fast either, because the long trace lengths are antennas so you'll end up in EMF emission regulations hell on the one side, and signal integrity issues on the other side. On top of that come losses from inductive and capacitive coupling.

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