Office International H 8002

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Calculators: Handheld: Office International H (aka 8002)

		Size (approx):	84mm x 134mm x 26mm (max) (w,h,d) Weight 142g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries, 0.35W. It accepts an adapter (6V DC 100mA) through a socket on the top side to the right. The battery compartment has a black ribbon pull to aid removal of batteries.
		Case:	Two-piece white glossy plastic case. A neutral plastic display filter is very slightly inset and tilted. It gives a bright, easy to read display. A matt black plastic keyboard surround is headed by a black printed metallic plate with the brand, model on on switch label. The keys are large, medium travel, quite squishy with a soft metallic click.
		Display:	8 digit blue VFD, with a ninth digit for minus and error and indicators
		Features:	4 function calculator with percentages
		Age:	1975
		Manufacturer:	Unknown, made in Japan. Serial number 72230.
		Comments:	Wide but quality feeling calculator with bold, easy to read high contrast colour scheme. Rare brand that only appears to have issued a few models as far as I can tell. The logic is OK with good recovery but let down by the pseudo fixed decimal bug. The original case is squared soft black plastic with open top and half-moon cut-outs on the sides.

Components:	1 x cpu: Texas TMS 0851NC A7513 (date code week 13 of 1975) , 28 pin DIL 0.6" width black plastic 1 x 9 digit VFD single tube round face 1 x transistor 6 x diodes 5 x capacitors 6 x resistors 2 x resistor arrays 1 x transformer
Boards:	The keyboard assembly sits on top of the battery compartment and links to the main cpu board below via 14 stiff wires - three of which are actually diodes. Very similar to Decimo construction.
Construction:	Remove the two screws from the rear. The front section will easily come away but great care must be taken hinging this off the bottom edge gently. The front section will then pull away.

Logic comments:	The (CE/C) button is used to clear last entry of a number and a second press clears the whole calculator.
	Input overflow is suppressed, inputting a ninth digit is ignored
	There is automatic constant on all four functions
	Negative numbers are shown by a "-" in the immediate left hand digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers
	An overflow shows the result with a “C” (or “E” if negative) in the far left (ninth) digit and is recoverable using (CE/C)
	Divide by zero results in zero and a "C” in the far left (ninth) digit and is recoverable using (CE/C)
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to give "1.000" which remains a three digit fixed number until more digits are required or you use multiply or divide.

manual

The (poor condition) manual to the left is a single sheet, folded paper measuring 297mm by 210mm. Whilst mine is folded into eight panels I suspect that originally it was just folded in half.

Note that the picture shows a calculator with no branding, no model number, and a black case front rather than white. The rear (printed in black and green) has some basic specifications and plenty of examples for such a simple calculator. The latter section is headed by the text:

Model "________" Calculation Examples

but mine has not been filled in or stamped.

With the front removed you can see that the construction is very similar to the GICO / Decimo format. Keyboard supported on top of the battery compartment and joined to the cpu board below. Most components are obscured by the keyboard.