Commodore Minuteman 2 (Version 1)

Date of introduction:  June 1972 Display technology:  LED-modules
New price:  $179.00 Display size:  8
Size:  6.0" x 3.5" x 1.7"
 153 x 90 x 44 mm3
Weight:  14.0 ounces, 396 grams Serial No:  R107202
Batteries:  6*AA NiCd Date of manufacture:  mth 06 year 1972
AC-Adapter:  MM-Type A
 7.2V 225mA DC, 7.0V 45mA AC
Origin of manufacture:  USA
Precision:  8 Integrated circuits:  TMS0103, 2*SN75491, 2*SN75492
Memories:   Displays:  9*Monsanto MAN-3A
Program steps:   Courtesy of:  Joerg Woerner

Commodore Business Machines (CBM) introduced with the C110 already in September 1971 their first portable electronic calculator, actually a rebranded Bowmar 901B, better known as Bowmar Brain.

While the C110 was a rather short-lived product, did it pave the way to an incredible success story. Its successor Minuteman 1 was introduced within just a few months and started a completely different design language but still using Bowmar electronics. 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.

Calculator Introduction Design Electronics Calculator Chip Keyboard Display
C110 September 1971 Bowmar Bowmar TI TMS0103 TI Klixon Monsanto MAN-3A
Minuteman 1 January 1972 Commodore Bowmar TI TMS0103 TI Klixon Monsanto MAN-3A
Minuteman 2
Version 1
June 1972 Commodore Commodore
TI TMS0103 TI Klixon Monsanto MAN-3A
Minuteman 2
Version 2
September 1972 Commodore Commodore
TI TMS0103 Commodore
Wild Rover Corp.
Monsanto MAN-3A
Hewlett Packard
Minuteman 2SR February 1974 Commodore Commodore
National Semiconductor

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

Dismantling the featured Minuteman 2 (MM.2 Version 1) manufactured in June 1972 by Commodore reveals a major change compared to its predecessor MM.1. While the the MM.1 made use of the electronics known from the Bowmar 901C, uses this MM.2 a printed circuit board (PCB) with a bold mark reading RAVEN 11870.

The main components of the two calculators are pretty similar but Commodore dropped with the MM.2 the [D] button for the power-saving mode and covered the respective key on the Texas Instruments Klixon™ keyboard with a sticker.

The display module of the MM.2 looks familiar to us, it is still using an array of 9 Monsanto MAN-3A 7-Segment LED modules.

In an additional effort to reduce manufacturing costs of their offerings, Commodore even changed the charger power supply design and replaced the original Bowmar chargers with a much more compact MM-Type A product.

Klixon™ is a trademark of Texas Instruments.

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© Joerg Woerner, October 30, 2021. No reprints without written permission.