Decimo Super Vatman type IV

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Calculators: Handheld: Decimo Super Vatman (type iv)


		Size (approx):	83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 152g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries. Also accepts adapter/charger (6V, undefined, 3.5mm centre positive) through a top side socket on the right. Take regular alkaline or rechargeable batteries. A sticker in the manual states that dry cell batteries must be removed whilst using an adapter. Recharging takes 9-10 hours and the calculator must be off.
		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 and has a black printed on/off switch label. 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 and overflow indicators
		Features:	Standard four function with percentages and square root
		Age:	estimate 1975
		Manufacturer:	Not mentioned, made in Japan. Serial No. 1201425
		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 original case is soft black plastic with and open top and top-side cut-outs. Very similar to the Decimo Super Vatman M and in fact uses the same cpu and has the same manual. It appears that this is a later cosmetic revision.

Components:	1 x cpu; NEC µPD946C R58216 28 pin DIL, 0.6" width black plastic 1 x 9 digit VFD; single tube flat face: Itron FG95A IG 1 x transistor 6 x diodes 7 x capacitors 6 x resistors 2 x resistor arrays 1 x transformer: SD06 Sumida
Boards:	The keyboard assembly (CA2412) sits on top of the battery compartment and is attached to the main cpu board (740051) below with a 14 wires.
Construction:	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 Clear Entry key (CE) is used to clear an input number, and a second clear key (C) to completely reset the calculator
	Overflow on the input of a number is not suppressed - typing in nine digits results in overflow. "C" is shown in the ninth (far left) digit and is not recoverable.
	The constant function is automatic on all four functions
	The negative sign is shown in the far left ninth digit thereby allowing full eight digit negative numbers.
	Memory store is flagged by the ninth (far left) decimal point alight.
	Overflow is shown by a "C" in the ninth (far left) digit ("E" if negative) . Error is recoverable by repeated dividing by ten.
	Negative square roots are allowed and result in a negative answer
	A divide by zero error is shown by a "C". It is not recoverable.

	The manual shown on the left is 120mm x 80mm and its eight fan-fold pages are printed in blue only. Nowhere in the manual is the make or model number referred to, so I guess they were trying to make the booklet as generic as possible. Though the keyboard layout is correct you can see that the top two memory buttons are labelled differently.