Decimo Super Vatman type III

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Calculators: Handheld: Decimo Super Vatman (type 3)


		Size (approx):	83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 144g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries. Also accepts adaptor/charger (6V, 200mA, 0.3W 3.5mm centre positive) through a top side socket on the right. Takes regular alkaline or rechargeable batteries. Dry cell batteries must be removed if using an adapter. Charge time is quoted as 9-10 hours with the calculator off.
		Case:	Chunky two piece plastic case. The bottom section is beige, top is matt black. An oversized green display filter, which is flat and almost flush, has a white printed model name and gives a bright display. The Decimo logo is black printed metallic panel that sits in its own recess. The keyboard surround is brushed aluminium . Top is slightly tilted upwards, including the back, which causes the calculator to rock, especially with no batteries to weigh it down.
		Display:	8 digit green VFD display – with a ninth used for negative, overflow and memory indicators
		Features:	Standard four function with percentages, square root, reciprocal, squares, pi, and four function memory
		Age:	1974
		Manufacturer:	Not mentioned, made in Japan. Serial No. S1108580 (also 501 81987)
		Comments:	Classic calculator that has a quality feel in the hand. The logic is a little shaky (with negative square roots and pseudo fixed decimal bug) but has a useful range of functions. Imbalance on the desk is odd. For those non-UK viewers, VAT stands for Value Added Tax - the purchase tax system in the UK. The original case is soft black plastic with open top and Made in Japan embossed on the rear.

Components:	1 x cpu; Rockwell A1241PA 7449 (week 49 of 1974) 42 pin staggered DIL, 0.6" width 1 x 9 digit VFD; single round faced tube 2 x transistors 5 x diodes 6 x capacitors 6 x resistors 2 x resistor arrays 1 x transformer
Boards:	The keyboard assembly (8000-Y4) sits on top of the battery compartment and is attached to the main cpu board (8D1M) below with 12 strong wires.
Construction:	Front can be gently prized off after using the coin guide at the top. Squeeze the cream plastic sides so the lugs separate without breaking and then hinge from the bottom.

Logic comments:	The (C) key is used once to cancel an entry whilst a second press clears the whole calculator
	Input overflow is suppressed inputting an ninth digit is ignored
	Negative numbers are shown with a "-” in the far left (ninth) digit, thereby allowing full eight digit negative numbers.
	There is an automatic constant on multiply and divide. There is also a sort of automatic constant on plus and minus by pressing the operator repeatedly.
	The change sign function can be used in mid number entry.
	Divide by zero shows “o” in the far left (ninth) digit and is recoverable using (C).
	Overflow shows the result and “o” in the far left (ninth) digit and is recoverable using (C)
	(EX) is used to exchange the display contents with the last register so that (9)(/)(3)(EX)(=) gives the inverse “0.3333333”
	Negative square roots are allowed and give a negative number.
	Memory storage is indicated with the far left (ninth) digit decimal point alight.
	Memory functions are two key operations; (M)(+) to add, (M)(-) to subtract, (M)(=) to recall and (M)(C) to clear
	It suffers the pseudo fixed decimal bug: (1)(+)(.)(0)(0)(0)(=) gives "1.000" which remains a fixed three digit deciomal number until you need more or use multiply or divide