Decimo Super Vatman M

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Calculators: Handheld: Decimo Super Vatman M

	Size (approx):	83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 142g excluding batteries (manual says 150g).
	Power:	6.0V DC, 4 x AA size batteries, 0.3W. Also accepts adapter/charger (undefined) through a top side socket on the right. You can use the adapter to charge rechargeable batteries but the switch must be in the Off position. Charging time is about 9 - 10 hours.
	Case:	Chunky two piece plastic case. Bottom is beige, top is matt black. Oversized, wrap over green display filter has painted logo. Decimo logo is metal inset panel. 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. Keys are squishy but positive to use.
	Display:	8 digit green VFD display - ninth used for minus and memory sign.
	Features:	Basic four function with percentages. Function button used to select squares, inverse, pi, change sign and square roots. Four function memory.
	Age:	estimate 1976
	Manufacturer:	Decimo Electronic Handy Calculator. Made in Japan. Serial No. 1227602
	Comments:	Classic calculator which has a quality feel in the hand. Imbalance on the desk let it down. Original black plastic case has top cover which is open top. For those non-UK viewers, VAT stands for Value Added Tax - the purchase tax system in the UK. No input suppression and negative square roots let the logic down a bit.

Components:	1 x cpu; NEC µPD946C R61076 (week 10 of 1976?) 28-way DIL 1 x single tube 9 digit VFD tube 1 x transformer 1 x transistor 7 x capacitors 8 x resistors 1 x resistor array 4 x diodes
Boards:	The keyboard panel rests on top of the battery compartment and is joined to the keyboard (ref CA2423-03-S) by 10 screws. A flexible 14-way connector joins this to the main board. You do not need to remove the three screws in the battery compartment in order to lift out the keyboard board or open the case.
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.

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.
	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.