[Ken Shirriff] completely reverse engineers the 1974 Sinclair Scientific calculator

reverse-engineer-sinclair-scientific-calculator

Wow. Seriously… Wow! The work [Ken Shirriff] put into reverse engineering the Sinclair Scientific is just amazing. He covers so much; the market forces that led [Clive Sinclair] to design the device with an under-powered chip, how the code actually fits in a minuscule amount of space, and an in-depth look at the silicon itself. Stop what you’re doing a read it right now!

This calculator shoe-horned itself into the market when the HP-35 was king at a sticker price of $395 (around $1800 in today’s money). The goal was to undercut them, a target that was reached with a $120 launch price. They managed this by using a Texas Instruments chip that had only three storage registers, paired with a ROM totaling 320 words. The calculator worked, but it was slow and inaccurate. Want to see how inaccurate? Included in the write-up is a browser-based simulator built from the reverse engineering work. Give it a try and let us know what you think.

Now [Ken] didn’t do all this work on his own. Scroll down to the bottom of his post to see the long list of contributors that helped bring this fantastic piece together. Thanks everyone!

[Thanks Ed]