That's a very interesting board! It came out in 1976 (four years before the 8087) and cost $499 assembled, equivalent to $2900 in current dollars, so it was expensive. It was really a decimal processor built from simple TTL parts, and had four microcoded instructions: add, subtract, multiply, and divide. Arithmetic used the 74LS181, the very popular ALU chip. (It did multiplication with repeated addition; there's no ROM with digit products, unless that was a later version.) The "small RAM" was very small by modern standards: four 4-bit registers that each held 16 digits. Each register was implemented with a 74S189 chip.

The microcode is available, so it would be a fun project to write a simulator that runs the microcode.

Manual and schematics are here if anyone is looking for them: https://bitsavers.org/pdf/northstar/boards/North_Star_Floati...

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tasty_freeze a day ago | parent [-]

My mistake -- what I wrote was from memory so I got the bit wrong about the multiplier ROM. I must have confused that detail with the design of the Wang 2200 computer, which had double precision BCD float math and did in fact have a 4b x 4b multiplier ROM.

https://www.wang2200.org/

(I'm the guy behind the wang2200.org domain)

	▲	rnewme a day ago \| parent [-]
		Lovely page, I enjoyed it lots. Especially this: “The first time I programmed a computer was in the fall of 1978 at LTHS, Lyons Township High School, in La Grange, IL. It changed my life. For a long time I couldn't think of anything else but programming computers, and it hasn't yet completely worn off.” Calms me down and gives hope. I started feeling like losing the programming spark is just behind the corner more and more during the past decade (working for money), yet decade and some before that was so exhilarating. But now I think, you've started 20 years before I was born!