Commodore Minuteman 2 (Version 2)

Date of introduction:  September 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:  12.9 ounces, 366 grams Serial No:  R438691
Batteries:  6*AA NiCd Date of manufacture:  mth 09 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:  Hewlett Packard 5082-7450
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 2) manufactured in September 1972 by Commodore reveals two obvious changes compared to a MM.2 Version 1 manufactured three months earlier:

The Texas Instruments Klixon keyboard was replaced with a Wild Rover Corp. keyboard moving the [ON/OFF] switch next to the [K] switch
The nine Monsanto MAN-3A 7-Segment LED modules were replaced with a Hewlett Packard 5082-7450 LED display

The printed circuit board (PCB) of the MM.2 Version 2 remained unchanged from its predecessor and sports a bold mark reading RAVEN 11870.

The 9-digit Hewlett Packard 5082-7450 display of the featured MM.2 Version 2 was manufactured by Hewlett Packard and uses a combination of one 4-digit HP 5082-7414 and one 5-digit HP 5082-7415 end-stackable module, each.

We recently discovered a Commodore Minuteman 2 (MM.2 Version 2) manufactured in May 1973 and decided to give it a full tear down - just to discover an array of 9 Monsanto MAN-3A 7-Segment LED modules again.

The PCB of the MM.2 Version 2 manufactured in May 1973 is identical to the PCB of the MM.2 Version 1 and sports a bold mark reading RAVEN 11870.

The electronics of the Commodore Minuteman 2 is centered around a Texas Instruments TMS0103 single-chip calculator circuit and - like most early designs of the wildly successful TMS0100 family - two SN75491 Segment Driver chips and two SN75492 Digit Driver chips, each. The remaining components on the PCB are mainly used to generate the necessary supply voltage of the TMS0103 and its clock signal for the internal timing.

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.

The keyboard assembly was manufactured on April 6th, 1973 by Wild Rover Corp. in Norwood, New Jersey and seems to be pin-compatible with the original Texas Instruments Klixon design introduced already in 1971.

The Commodore Minuteman 2 is like its predecessor Minuteman 1 powered by 6 internal, rechargeable AA-sized batteries and uses an external MM-Type Charger / Power Supply.

Klixon™ is a trademark of Texas Instruments.

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