H. Edward Roberts (1941–2010)

2021 Review:
The author of this book, Ed Roberts, was the guy who developed the Altair 8800 personal computer. But before that, he was a calculator designer.

After looking at my 6-year-old rather flippant review to this book, I figured it was time to re-borrow and re-read this book. Now that I've been teaching digital electronics for 6 years I've gained an appreciation for "ancient technology" and seeing how things have been done in the past.

This book was published in 1974. Solid state memory was a fact but couldn't compete with magnetic memories (and honestly, it couldn't and didn't for another 40 years). CMOS wasn't a competitive technology yet. Displays all required extremely massive voltage levels (from today's 3.3V or 5V standards).

I was floored by how complicated something as simple as key encoding was. Encoding circuitry using diodes was used for all of the keypad inputs. Multiplexing of displays, which is commonly used today and made trivial with microcontrollers and their timed interrupts, was a new technique used to make decoding circuitry simpler. But again, all of the displays used in the 1970s required either a lot of driving transistors for current, or high voltage levels for their anodes. Even the clock circuits used an astable oscillator of odd NAND gates in sequence rather than a crystal. Oh, and apparently, human beings actually sat at a desk and DREW PCB layouts? !!!!!

I would love to be able to go back in time and show the author my TI-83+ calculator. It has a large LCD screen, dozens of buttons with a shift and alpha function, PLUS a ton of menus that not even I have completely explored, which further expands the input options. The calculator can do so much math that I probably haven't even used 20% of it. And it basically operates on one TI microprocessor. Even my "crappy" TI-30X calculator is more powerful than even the most expensive calculators in this book.

So I think it's really fascinating what people were able to accomplish with so much less. There were no microprocessors or microcontrollers back then. And even today, in 2021, there are dedicated calculator microprocessors because they do require a lot of different functionality than your general purpose microprocessors have.

I appreciated the author's predictions of the future. He predicted a calculator that could also keep a calendar, diary, and addresses. It reminds me of the 1990s Palm Pilots... the grandparent to today's smart phones. We can do all that... and so much more!

Anyway, this book is a really interesting look at the current state of technology for calculators in the 1970s. It is a thinly veiled advertisement for MITS, which, considering that company has ceased to exist many years ago, is no longer annoying as it probably was when this book was first published.

2015 Review:
If you're interested in how "advanced scientific calculators" were assembled in the mid-70s, then this is your book! Otherwise, I think this thing probably belongs in a science history museum more so than a modern science library.… (more)