Decimo Vatman X

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Calculators: Handheld: Decimo Vatman X


		Size (approx):	83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 140g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries, 0.3W. Also accepts adapter/charger (undefined) through a top side socket on the right. The on/off switch is in the middle of the top side and is a three position switch for On/Off/Charge. A note on the back sticker reminds you to only use the charge position with rechargeable batteries in place.
		Case:	Chunky two piece matt plastic case where the bottom is light grey and the top black. Oversized, wrap over green display filter has a white printed model name. It has frosted edges around the display and gives a very clean bright image. A black printed metallic sticker with the brand name 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. Keys are squishy but positive to use.
		Display:	8 digit green VFD display with a ninth digit on the far right for negative and error indicators.
		Features:	Basic four function with percentages, change sign and register exchange
		Age:	1975
		Manufacturer:	Decimo Electronic Handy Calculator. Made in Japan. Serial No. X 107810
		Comments:	Classic calculator which has a quality feel in the hand. The logic is sound. The imbalance on the desk lets lets this otherwise nice design down. For those non-UK viewers, VAT stands for Value Added Tax - the purchase tax system in the UK. The original cover is soft black plastic with a flip over lid and front popper closing.

Components:	1 x cpu; Rockwell A5911PA 7539 (week 39 of 1975) 42 pin Staggered DIL, 0.6" width 1 x 9 digit VFD; single round faced tube 2 x transistors 3 x diodes 6 x capacitors 4 x resistors 2 x resistor arrays 1 x transformer: DCT-04 Zebra
Boards:	The keyboard assembly (A5911 GK161-16 Gikco) sits on top of the battery compartment and is attached to the main cpu board below with a 13-way ribbon block.
Construction:	The 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 key (C/CE) is used once to clear an input number, and a second time to completely reset the calculator
	Overflow on the input of a number is suppressed - typing in nine digits ignores the ninth
	The constant function is automatic on all four functions
	The negative sign is shown by a "-" in the far right (ninth) digit thereby allowing full eight digit negative numbers.
	A divide by zero error is shown by "0.0.0.0.0.0.0.0." and is recoverable using (C/CE)
	Overflow shows the result and all eight decimal points alight is recoverable using (C/CE)
	The change sign function can be used in mid number entry
	The Exchange key (EX) is used to invert the current display and last number entered,

	Here you can easily see the components crammed into the top of the case - the whole of the bottom being taken up by the keyboard assembly on top of the battery compartment. You can make out the symbol cluster on the right side of the VFD tube and the staggered pins of ICs common to Rockwell.
	The large format manual measures 148mm by 105mm with a green cover and black only on the inside. The eight printed pages are in English only and give quite a few examples along with specifications. It does not mention any brand throughout the text, so this is a generic manual. 5911, For Rechargeable Calculator V