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(04-10-2019 06:38 AM)Steve Simpkin Wrote: [ -> ]
(04-09-2019 03:25 PM)agarza Wrote: [ -> ]I have no idea how Sinclair did such a feat. I have run out of memory.

Here is how Sinclair's Nigel Searle achieved a scientific calculator (non-programmable) in under 320 words of code.

Wow. Incredible what they accomplished in 1974.

I opted to use 64 bit registers, this will give pretty good accuracy, at least better than most old HP calculators. But this comes with a great cost. Doing simple operations on an 8 bit processor take a lot of processor cycles and memory.
Regarding the Sinclair, I'm blown away on how they could fit so many functions in such a compact code.

(04-12-2019 01:00 PM)Eddie W. Shore Wrote: [ -> ]Regarding the Sinclair, I'm blown away on how they could fit so many functions in such a compact code.

Clive Sinclair is a true genius of an inventor. The T.A.Edison of the 1970ies and 80ies. And totally self-taught - he did not waste a single day studying at university. The ZX-81 which was my first home computer came with 1kB of RAM. And this included the video memory. There was even a chess program which fitted the remaining part of the the RAM. It did not play well at all, but it "knew" the rules.

An absolute must-have for DIYers is the Sinclair PDM35 multimeter, a by-product of his calculators. One should not work on a vintage calculator with any other than this multimeter :-)


PS: Sinclair now makes strange lookig electric bikes, but under a different trade name.

PPS: For DIYers there is an Arduino-based reproduction kit of the Sinclair Scientific: https://www.tindie.com/products/ArduinoE...-emulator/
Unfortunately it is out of stock right now, but maybe there will be another production run.
Yes Clive Sinclair is a genius and was almost unparalleled at getting his engineers to extract functionality out of a bare minimum of parts. I loved his practicality too.
"Scientific calculators usually provide constants such as e and π but there was no space in the ROM for these constants. The Sinclair Scientific used the brilliant solution of printing the constants on the calculator's case - the user could enter the constant manually if needed."

I only owned one Sinclair product, the Sinclair Wrist Calculator which I built from a kit. At the time it was the smallest electronic circuitry I ever had to solder. It did work when I was finished but the case had interference problems with the slider and was fragile. I played with it until the batteries died (6 mercury cells) and did not replace them as they cost almost as much as the calculator.

If you get a chance to see the drama Micro Men, it is a very entertaining (if not super accurate) TV movie about the rise of the British home computer market. It focuses on the rivalry between Sir Clive Sinclair, who developed the ZX Spectrum, and Chris Curry the man behind the BBC Micro. I believe it is viewable on Youtube.
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