undefined | Better HN

0 pointsChuckMcM10y ago0 comments

I have a 12 bit CPU at home that is implemented out of standard 74xxx TTL chips, its called a PDP-8/e :-). Not to take away from the Nibbler design, its great, but using TTL logic to build CPUs was a thing for a pretty long period of time (computer wise), probably 10 years from 1971 - 1981. 1981 was the year IBM introduced the IBM PC and a lot of people realized that bespoke CPU architectures were a luxury they could no longer afford.

0 comments

PythonicAlpha10y ago

Of course the technique itself is not that new, but it is still amazing, because of the real few chips used. Of course the microcode ROM replaces plenty of those, but still it amazes me, how few chips make up for a workable CPU.

I guess, the PDP has at least 10 times more (equivalent) chips inside.

ChuckMcMOP10y ago

You know, I've never actually counted them although we can estimate them from pictures on the web

M8310 - 53 chips (http://www.classiccmp.org/hp/My%20PDP-8%20Cards/M8310.jpg)

M8300 - 64 chips (http://www.classiccmp.org/hp/My%20PDP-8%20Cards/M8300.jpg)

So 117 chips, so not quite 10X but the nibbler does have an LCD display and if you add the PDP-8/e programmer console to the mix you're probably close to 170 chips. So great estimate!

j / k navigate · click thread line to collapse