Those of you with an interest in microcomputer history will know that there is a strong crossover between the path of electronic calculator evolution and the genesis of the integrated CPU. Intel’s 4000 was famously designed for a calculator, and for a while in the 1970s these mathematical helpers were seen as the wonder of the age. [Simon Boak]’s calculator is a curious throwback to that era, as it’s not a decimal calculator as we’d know it but a hexadecimal device that simply computes using the functions of the famous 74181 ALU chip.
An ALU, or to give it its full name an Arithmetic Logic Unit, is a component of a CPU with two inputs and one output that can perform any of a range of binary functions upon the two inputs and return the result on the output. This calculator has two of them for eight bits of raw adding power, with a hexadecimal keypad for setting the inputs and a set of 7-segment displays for showing the results. It’s housed in an achingly retro folded sheet metal console case with wooden end pieces that would have graced any engineer’s desk with pride back in about 1975. We may not need one, but we really want one!
If the 74181 is a mystery to you then fear not, because chip master [Ken Shirriff] has produced some handy explanation work on its operation.
Thanks [Ted Yapo] for the tip.
Beautiful!
A small typo: Intel’s 4004, not 4000.
I love that he used the same font that was used for HAL9000 on the display panel. It is an absolute thing of beauty. (Ref: https://typesetinthefuture.com/2014/01/31/2001-a-space-odyssey/)
A thing of beauty and a joy forever.
scnr…
I think it has a bit of that MINIVAC 601 vibe to it
Woah, that link should come with a warning label:
“Warning, you’re about to lose the next 2 hours of your life here”
Thank you :) Using a period-accurate font was quite important to me on this
Are there other ALU chips available for consideration?
(I’d like to put my hex displays to work)
Not that I’m aware of. Pretty much after this was the move to microprocessors