We’ve talked about the Sinclair scientific calculator before many times, and for some of us it was our first scientific calculator. If you can’t find yours or you never had one, now you can build your own using — what else — an Arduino thanks to [Arduino Enigma]. There’s a video, below and the project’s homepage on Hackaday.io describes it all perfectly:
The original chip inside the Sinclair Scientific Calculator was reverse engineered by Ken Shirriff, its 320 instruction program extracted and an online emulator written. This project ports that emulator, written in Javascript, to the Arduino Nano and interfaces it to a custom PCB. The result is an object that behaves like the original calculator, with its idiosyncrasies and problems. Calculating PI as arctan(1)*4 yields a value of 3.1440.
Special care was taken in the design of the emulator to match the execution speed of the
original calculator, which varies from acceptable to atrocious for trigonometric functions involving small angles.
Oddly, the calculator started life as a hack on the KIM-1 UNO. However, six board revisions changed the layout quite a bit and made the emulation more and more accurate both software-wise and physically. If you fancy a close look at an original Sinclair we subjected one to a teardown.
The KIM-1 UNO board has had a lot of life poured into it. We used it as a clock and an 1802 emulator. Oscar even built off of the 1802 code to add video output.
Brings back happy memories of working at Sinclair, including coding the Scientific.
Well, tell us more…
+1 Hackaday folks: if Nigel is willing to talk, an interview about these amazing days of Sinclair development would be so valuable, informative and help to preserve a unique moment in time… With the recent passing of both Sir Clive and Rick Dickinson (mechanical designer for many things Sinclair and the Jupiter Ace), time is of the essence to get the unique perspectives of those in the thick of it… Thanks in advance
Recent passing of Sir Clive? What are you talking about?
That ebike couldn’t pass anything, neither could the C5.
I think the OP is getting his Clives mixed up, it was the author Clive Sinclair who passed away last month.
I wanted to read the assembler listing but it won’t scroll either on FF or Chrome. Is it just my computer being stupid?
Hmm, you can only read it by using the calculator, damn that makes it hard to read.
You can scroll the code – you just have to stop the simulation first, by clicking on the square stop button.
Pause the emulation so the loop isn’t running and then you can scroll it.
It scrolls for me but it resets to where the program is, but it is freely scrollable when you turn the calculator off.
I found one of these calculators recently in a box of stuff from a non-air-conditioned storage room near the ocean. All parts of it were corroded to hell from the salt air; still brought a tear to my eye to drop the thing in the trash can.
” Calculating PI as arctan(1)*4 yields a value of 3.1440.” …….. UH !?????
What am I missing here ?
If that computation yields PI in any form, what does 2+2 give you ? 7 ? 128 ? 14 ?
On my HP25 (and HP67) that calculation: arctan(1) = 45 x 4 = 180
radians:
https://en.wikipedia.org/wiki/Radian
atan(1) = 0.78539816
*4 = 3.1415927
−π = 0
using arctan(1)*4 is fine for pi (2pi=360 after all) me thinks the issue is with sinclar’s arctan ???
Yes it is a known bug which the emulator faithfully reproduces.
6, for sufficiently large values of 2
Clearing out a desk drawer… it _had_ to be done: https://www.instagram.com/p/BSFBTatlfVQ/
I have built the Sinclair scientific calculator but cannot program it. Every source of programs for the calculator give errors when I try to compile it on Arduino.
Can someone please help me overcome this problem and enable me to program the calculator?