THE "COMPULATOR" BOOK

[Craig Bladow]

I purchased and read this book, "The "COMPULATOR" BOOK - BUILDING SUPER CALCULATORS AND MINICOMPUTER HARDWARE WITH CALCULATOR CHIPS" by R.P. Haviland in the late 1970's. I was a high school student at the time and the title of the book led me to hope that I could build a computer from calculator chips. To this day I remember being disappointed by the book but couldn't quite remember why, so I re-read the book recently.

Published in July of 1977 and containing references to publications dated as late as December, 1976 it is notable the title uses minicomputer instead of microcomputer even though microcomputers are mentioned in the text. While HP was selling programmable calculators before this book came out, no mention is made of them, perhaps because the book made use of commercially available calculator chips that were the basis of much simpler machines.

The book contains excellent material on calculator operating principles and their components. It mentions reverse polish notation, as well as forward polish notation, of which I was not aware of.

The book presents designs, and even PCB layout patterns, for circuits to automatically complete calculator key input circuits as well as to decode seven segment display signals to generate outputs.

Yet it never completes the implied promise to build a mini-computer. One could turn a calculator into a counter, or into a micro-computer math operation accessory but without the ability to perform a test and change the execution path based on the result no computer could be made.

Then, in chapter 13 (of 13) the author finally writes, "When one considers the matter of additional experimental projects based on calculator chips, it seems automatic to start thinking about making a computer out of the chip. The author has considered this a number of times, and so far has come to one decision--don't do it; it isn't worthwhile."