Commodore Minuteman 1

The Commodore Minuteman 1 followed almost immediately the Commodore C110, based on the famous Bowmar 901B.

"The Minuteman 1 was the world's first solid-fueled Intercontinental Ballistic Missile (ICBM), and has been the mainstay of the USAF's ICBM force ever since its deployment. Because international arms reduction treaties...." © Mark Wade, 2003.

These are first the words of an introduction to the Minuteman 1 missile developed by Boeing in the early 60s. But here we are talking about a very odd calculator manufactured by Commodore Business Machines, Inc. (CBM) in Santa Clara, California.

The Minuteman 1 nicknamed "MM.1" is a big calculator, compared with the sleek Bowmar 901B it adds about 50% of weight and outperforms it in all dimensions. The side-view of the MM.1 gives a good impression of the sheer size.

Exploring the roots of the featured Commodore Minuteman 1 manufactured in February 1972 by Commodore is an interesting experience. Without any tools the two halves of the housing can be separated. This is accomplished with an additional connector between the batteries and the calculator electronics.

Removing the cover plate of the front-housing reveals a big surprise. The main printed circuit board (PCB) of the MM.1 is identical with the Bowmar 901C and carries even its original Bowmar part number PM901-400/E.

Looking closer at the two calculators shows some differences between the MM.1 and the Bowmar 901C. The featured MM.1 makes use of discrete LED-displays manufactured by Monsanto, Bowmar relies on their own Optostic displays. Please notice the different placement of the switches.
Karl Schmitz - proud owner of two MM.1 reported that they use the Optostic display, too.

With the Commodore MM.1 using the electronics of the Bowmar 901C, it consequently makes use of an external power supply with identical specifications.

While the C110 manufactured by Bowmar marked the entry of Commodore into the market of portable electronic calculators, started the Minuteman 1 the design language used with new products. The next evolution - consequently named Minuteman 2 - replaced first the Bowmar electronics and then the Texas Instruments Klixon™ keyboard with Commodore's own designs. It took another iteration with the Minuteman 2SR to drop even the Texas Instruments calculator chips and replace it with a design from MOS Technology, a company Commodore acquired in October 1976 and fueling in October 1977 a revolution with the PET2001 (Personal Electronic Transactor), the best selling "Personal Computer" of its time.

The next iteration of Commodore's design language was introduced in 1974 with the Minuteman 3 series of calculators.

Klixon™ is a trademark of Texas Instruments.

If you have additions to the above article please email: joerg@datamath.org.

© Joerg Woerner, September 29, 2003. No reprints without written permission.