Decimo Super Vatman M type II

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Calculators: Handheld: Decimo Super Vatman M (type II)


		Size (approx):	linked not started 83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 140g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries. Also accepts adapter/charger (6V, 0.45W, 3.5mm centre positive) through a top side socket on the right. T
		Case:	Chunky two piece plastic case. The bottom section is light grey, 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 with black printed text for the power switch. Top is slightly tilted upwards, including the back, which causes the calculator to rock, especially with no batteries to weigh it down. The keys are soft and squishy but work well enough.
		Display:	8 digit green VFD display with a ninth digit for negative, memory and overflow indicators
		Features:	Standard four function with percentages, square root, pi, change sign and four-function memory
		Age:	1978
		Manufacturer:	Made in Japan, serial number 16592
		Comments:	Classic calculator that has a quality feel in the hand. 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 logic is quite robust and only let down by the lack of recovery. The original case is thin black plastic with open top and half-moon cut-outs front and back.

Components:	1 x cpu; NEC D1803C E7Z56D (late 1977) 28 pin DIL, 0.6" width black plastic 1 x 9 digit VFD unit, single glass tube flat faced 1 x transistor 3 x diodes 6 x capacitors 4 x resistors 1 x transformer
Boards:	The keyboard assembly (GK-158-25 GICO T-2 W-801C) sits on top of the battery compartment and is attached to the main cpu board below with 14 strong wires. The main board is held in place by a plastic pillar and the power socket. The Gico sticker (53.2.13) is date code 13 February 1978
Construction:	The front can be gently prized off after using the coin guide at the top. Squeeze the grey plastic sides so the lugs separate without breaking and then hinge from the bottom. You do not need to remove the three screws in the battery compartment as they hold the assembly to the back.

Logic comments:	The (CE/C) key is used once to clear an input number, and a second press completely resets the calculator
	Overflow on the input is suppressed: keying in a ninth digit is ignored
	There is automatic constant on multiply and divide only
	Overflow shows the result and "C" (or "E" if negative) in the far left (ninth) digit and is not recoverable
	Divide by zero shows zero and "C" in the far left (ninth) digit and is not recoverable
	Negative numbers are shown with a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers.
	The change sign key can be used in mid number entry but not before
	Memory store is indicated by the decimal point of the far left (ninth) digit
	Overflow in memory is indicated by zero and "C" in the far left (ninth) digit and the memory retains the original number
	Negative square roots are not allowed and result in zero and "C" in the far left (ninth) digit and is not recoverable
	No bugs found

Typical of many Decimo calculators the GICO keyboard sits on top of the battery compartment and covers half of the main cpu board below. The main board is held in place by the plastic pillar (top left) and the power socket.

In this particular late model most of the components are hidden below the keyboard and the main IC is under the display unit.