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 Quirky Chips - from Moto, Signetics and others. 
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1640
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Landed on this page the other day - it describes some less well-known and slightly odd early microprocessors.
http://www.ganssle.com/articles/quirkychips.html

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Quote:
Motorola's MC14500 was a one-bit CPU the company called an "Industrial Control Unit."

RCA's 1802 - Any of the 16 registers could be the program counter, no call instruction

Signetic's 8X300 (second source, the original being Scientific Micro Systems SMS300) in 50 pin DIP with separate instruction and data busses, just 512 byte addressable data space. No interrupts. No stack, no calls. And no subtract. For much more on this, see "The History of the SMS300 and Signetics 8X300 Processors".

The 4004 had a hardware stack, on-board the chip. It was three levels deep.

Fairchild's eight bit F8 had no address bus but had a whopping 64 registers.


And there's a tantalising mention of the PICO1 as the first microcontroller - from Scotland, for Elliott computers. See here
http://www.spingal.plus.com/micro/

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Last edited by BigEd on Mon Sep 10, 2018 3:22 pm, edited 1 time in total.

fix broken image link



Mon Nov 21, 2016 9:45 am
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Joined: Tue Jan 15, 2013 5:43 am
Posts: 185
Quote:
Motorola's MC14500 was a one-bit CPU the company called an "Industrial Control Unit."

Thanks, Ed -- that site is worth a visit. I just subscribed to their newsletter.

As for the '14500, that's a chip that intrigued me back in the twentieth century when I first encountered it. It operates on data words that are one bit wide, and the opcodes are four bit, yielding just sixteen instructions. But, to my surprise, I found that Motorola's minimalist approach could be abandoned and replaced by something substantially simpler! :shock: :ugeek: :mrgreen: (With the '14500 you're expected to implement the Program Counter using external logic -- it's not included on-chip.)

See: One-bit Computing at 60 Hertz


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Tue Nov 22, 2016 3:16 am WWW

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1640
A practical application of the One Instruction Computer - marvellous!

I see Jack also has a video channel, mostly about embedded electronics which is his main thing, but one or two retro episodes, such as "Episode 11 - Getting Busted in New Jersey With Core Memory" (I'd have to take issue with his idea that mercury delay lines contain springs...)

He also has a history of computing here. I imagine there's more to be found on his site!


Tue Nov 22, 2016 11:40 am
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