Unknown 1000PR

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Calculators: Handheld: Unknown 1000PR


		Size (approx):	83mm (max) x 132mm x 30mm (max) (w,h,d) Weight 146g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries. It accepts an adapter (undefined) through a top side socket on the right. The on/off switch is in the middle of the top side.
		Case:	Chunky two piece matt plastic case where the bottom is light grey and the top black. Unusual small green display filter has a silver printed escutcheon. A black printed metallic sticker with the model number sits in its own recess. The keyboard surround is brushed aluminium. The 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 for negative and error indicators.
		Features:	Basic four function with percentages and square roots.
		Age:	1975
		Manufacturer:	Unknown, serial No. 510 09397
		Comments:	Unusual Decimo Vatman-type calculator that has a small window display filter rather than a wrap around one. The logic is OK but the lack of recovery and negative zero bug let it down. Appears to be the same as the Decimo Vatman Vantage. If anyone has any information on this calculator it would be a great help.

Components:	1 x cpu; Hitachi HD36290 5K11 (August 1975) 28 pin DIL, 0.6" width black plastic 1 x 9 digit VFD; single round faced tube 2 x transistors 5 x diodes 6 x capacitors 5 x resistors 2 x resistor arrays 1 x transformer: DCT-04
Boards:	The keyboard assembly (G800PKA36290 GK1613 GICO Japan 50.10.3) (date code 3 October 1975) sits on top of the battery compartment and is attached to the main cpu board (IL-9) below with a 15 strong wires.
Construction:	Front can be gently prized off after using the coin guide at the top. Squeeze the rear plastic sides so the lugs separate without breaking.

Logic comments:	The Clear key (CE) is used to clear an input number whilst (C) resets the calculator
	Overflow on the input of a number is suppressed - typing in a ninth digit is ignored
	The constant function is automatic on multiply and divide only
	The negative sign is shown by a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers.
	A divide by zero results in zero and "C" in the far left (ninth) digits and is not recoverable
	Overflow shows the result and a "C" ("E" if negative) in the far left (ninth) digit and is not recoverable
	Results of square roots are limited to five decimal places
	Negative square roots are not allowed and result in a answer with "E" in the far left (ninth) digit and is not recoverable
	The calculator suffers the negative zero bug; key in (1)(-)(2)(=) to give "-1" then key in (+)(1)(=) to give "-0"

	Exactly the same inside as the Decimo Vatman Vantage mentioned above. 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. The main CPU is underneath the keyboard to the left of the square root key.