Commodore Minuteman 3-M

		Home New Stuff Author Links Guest book Web-log	Adverts Bric-a-brac Calculators Components Ephemera Events	For Sale Glossary History Hit or Miss Radios Transport	Ultra Valves Wanted Metal Puzzles Clocks

Calculators: Handheld: Commodore Minuteman 3-M

		Size (approx):	70-75mm x 114mm x 28mm(max) (w,h,d) Weight 162g including internal batteries (100g without)
		Power:	6.0V DC, internal rechargeable battery, 0.2A. Also accepts adapter (undefined) through a socket on the top side in the middle. The manual states that four N size batteries can be used but this may refer to a variant of the model shown as it also refers to "rechargeable units only" in the instructions. There is a power save function.
		Case:	Two-piece smooth white plastic case in a small dumpy design used in many of the early minuteman series. A large black painted metal plate surrounds the red display filter and has a raised and silver painted logo and "on" label. The keyboard surround is stippled black plastic with individual raised boxes for each key. Typically commodore colours, the keys are short-travel squishy but work quite well.
		Display:	8 digit red LED (flat dot type) with ninth digit for negative, error and low battery indicators
		Features:	Four function with percentages, preset decimals and two function memory
		Age:	1973
		Manufacturer:	Made in USA, Serial No. 024739
		Comments:	Sits in the palm of your hand quite easily with a very clear wide angle view display. At first glance a basic calculator but it is enhanced by power save mode, unique but (I think) great percentage mode, low battery indicator and fixed decimal points - fabulous! The original shaped carry case is soft black plastic with flip over top and Velcro closing on the front. Two side flip-over sections help to keep the dust out. It is embossed with the Commodore logo on the front. I think the US version of this calculator is referred to as the MM3M but there is no mention of such a number on this example.

Components:	1 x cpu: MOS MCS 2521 A002 2673 (date code week 26 of 1973) 28 pin DIL, 0.6" width gold plated legs in its own socket 1 x IC display drivers: Texas SN75491AN 7322 and Texas SN74592N 7313 both 14 pin DIL, 0.3" width 1 x 9 digit red LED (no bubble lens) 1 x transistor 3 x diodes 5 x capacitors 3 x resistors (one on the rechargeable battery pack) 0 x resistor arrays 1 x transformer: Sumida Japan
Boards:	The keyboard assembly it fixed to the front and sits underneath the main cpu board (ref PCB 300348, Art 300349B, Assy 300350). They are joined by 13 insulated wires.
Construction:	Remove the two long screws from the back. The rear section comes off easily hinged from the bottom.

Logic comments:	(CE) cancels an incorrect numerical entry and (C) and clears the calculator
	There is no constant, instead you use the memory to store the constant
	Input overflow is not suppressed, inputting a ninth digit is causes "E" to be displayed which is not recoverable if it is the first number, it is recoverable using (CE) if it is the second number of a calculation
	Also, you can do a calculation using an overflowed input number and the "E" remains in situ!
	Negative sign is shown in the far left (ninth) digit thereby allowing full eight digit negative numbers
	Divide by zero shows "o" in the far left (ninth) digit and is not recoverable
	Overflow is shown by the result and "o" in the far left (ninth) digit and is not recoverable
	Memory storage is not indicated, you have to remember it.
	Using the memory is a two key operation; use (=)(M) to store a number and (M)(=) to use a number, i.e. (5)(X)(M)(=)
	There is a handy preset decimal notation system for multiply and divide only; to set the calculator to four decimal point mode use (C)(.)(=)(4) and switch off to reset.
	After about 20 seconds the display switches to power save mode by lighting the middle (fifth digit) "-" only. Touch a function or (=) to continue.
	Percentage is rather odd; 5% of 150 is done by (5)(%)(150)(=) to give "7.5"

box

The box on the left measures 90mm x 150mm and is 47mm deep. It could have held a small charger without a plug. It is printed in blue and one side has a red sticker saying "Rechargeable" implying again that there was a battery version. There is an internal card former that adds to the strength. Made in the USA.

On one side there is a printed serial number (in black) that matches the calculator.

manual

The manual is a 20 printed page printed in black only. It measures 78mm x 131mm and has an extra fold out perforated guarantee registration card.

There is plenty of informative text and clear examples of various calculations. Ref 300389, printed in the USA.