Decimo Super Vatman Office

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Calculators: Desktop: Decimo Super Vatman Office

	Size (approx):	195mm x 240mm x 30-65mm (w,h,d) Weight 1255g excluding cable
	Power:	Mains (240V 50Hz, 30mA) power only through a permanently fixed mains cable of considerable length.
	Display:	12 digit green VFD with additional symbol clusters at each end for memory (M), error (E) and negative (-). The latter is on the far left. There are unused symbols on the left cluster (a left pointing arrow), and on the right cluster (a I and II for double memory indication and a negative sign). The display has lower commas for thousand notation (and unused upper ones).
	Features:	Standard four functions with percentages, item count, three function memory, register exchange, delete, clear accumulator and average. Switches for AR/AL (accumulator?) summation mode, round down and fixed/floating decimal.
	Age:	1979
	Manufacturer:	Decimo Limited, made in Taiwan, serial No. 80090845.
	Comments:	A sturdy workman like calculator. At this late a date the components are minimal except for the keyboard matrix diodes. Sound logic with good range of "accounting office" functions and clear display. Plastic case on my example has been badly UV light yellowed.

Case and Design:	The base is made from smooth black plastic whilst the top section is a two-piece smooth cream (may originally have been white) and black plastic. The green display filter is recessed and angled steeply to give a clear bright image. The digit numbers are printed white on the filter along with labels for the negative, overflow and memory symbols. Above the display is a black and white printed metallic label that sits in its own recess. All the edges are rounded adding to the solid feel of this heavy calculator.
Keys and Switches:	They keys are well laid out, large hollow sounding click with long travel. A neat row of switches above them switch for accumulator control (AR/AL), Summation to memory (Σ), constant switch (K) and round down/round (5/4). A further sliding switch (I think this example is missing the knob) selects a (+F0246) decimal point. The raised labels for these switches are printed silver. The on/off switch is on the right hand side, nearly at the top.

Construction:	Remove the four screws from the bottom and the whole white front section will come off easily. Be careful not to lose the washers. As always with this type of unsealed keyboard, my example had accumulated loads of dust. The whole assembly is bolted to the rear section with sturdy screws and metal brackets. A whopping transformer and main board plugs show that little expense was spared.
Boards:	The main keyboard assembly sits loosely on top of four metal bars and is joined to the main cpu board via a 8-way and a 9-way ribbon cable. There are a surprising amount of diodes (ten) on the key matrix area. The shaped main cpu board (ref 12D) is attached to the rear with six screws and houses the bracket for the display. Most of the components are for the power supply.

Components:

1 x cpu: Texas TMS1371N2L MBSL 7945, 40 pin DIL, 0.6" width
1 x 12 digit green VFD display: flat tube with left and right symbol clusters: Futaba 13MT36
1 x transistor
17 x diodes (10 on the keyboard assembly)
4 x capacitors
3 x resistors
3 x resistor arrays
1 x mains transformer: TRL-054BS TCE

Logic comments:	(C/CE) is used once to cancel the last number entered and a second time to clear the whole calculator.
	(CA) clears the summation accumulator
	(IC) is item count - the number of numbers added to the accumulator
	(>) deletes the last number entered but can also be used as a error recovery key
	(00) allows more rapid number entry , especially in financial decimal mode (+ on the points switch)
	Input overflow is not suppressed, inputting a thirteenth digit results in an overflow that is recoverable using (>)
	Constant function is switched in with the "K" switch and operates on multiple and divide only
	The rounding switch can select round down (>) and round up/down (5/4)
	The decimal point switch can be selected between floating "F", fixed "6,3,2,1,0" and financial mode "+" for $x.xx entry
	Negative numbers are shown with a minus in the far left symbol cluster allowing full twelve digit negative numbers
	A summation switch "S" (sigma) adds the result of every calculation to the memory
	Divide by zero shows a "E" in the far left symbol cluster and is not recoverable
	Overflow shows the result and "E" in the far left symbol cluster and is recoverable using (C/CE)
	Memory storage is indicated by "M" in the far right symbol cluster
	The average key (AVG) is used to divide the contents of the accumulator by the item count
	The register exchange key (EX) exchanges the answer for the first number entered
	There is an accumulator control switch AR AL which I am not sure of the function