Imperial 80K

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Calculators: Handheld: Imperial 80K


		Size (approx):	62mm (max) x 92mm x 22mm (w,h,d) Weight 68g excluding batteries
		Power:	4.5V DC, 3 x AAA size batteries. It does not accept an adapter.
		Case:	Palm sized compact case made from two-piece matt black plastic construction. The top has a wrap around brushed aluminium panel printed black with the brand but no model name. An inset and tilted green plastic display filter give a bright but small display. The medium travel squishy keys have a soft click and work well. The on/off switch label is raised lettering. There are no information stickers on the rear, but there is one on the inside of the battery cover.
		Display:	8 digit green narrow VFD with a ninth digit for negative and error indication
		Features:	Standard four function with percentages.
		Age:	c1975/6
		Manufacturer:	Imperial Typewriter and Business Machines Ltd., Leicester, England. Made in Japan. Serial number 80K 69.01025626 is on the inside of the battery cover.
		Comments:	Very compact but quite thick calculator that is amazingly compact for its date. The display is equally tiny but quite bright. Similar to the Adler Sir and Triumph Sir. Good logic is only let down by the lack of recovery. The original case is soft black plastic with rigid corners that hold the square shape well. It has an open top and cut-outs either side to aid removal of the calculator.

Components:	1 x cpu; NEC µPD940C H5X26M, 28 pin DIL, 0.6" width black plastic 1 x 9 digit VFD; single tube round face 1 x transistor: C620 57E 5 x diodes 7 x capacitors 7 x resistors 2 x resistor arrays 1 x transformer: DCT22
Boards:	The main board (80-Fa) is underneath the keyboard assembly, and is joined by 12 stiff soldered wires: the whole lot sits loose in the case. Two paperclip like connections go from the battery terminals to two metal strips on the keyboard assembly.
Construction:	Remove the screw from the rear. You then have to carefully pop two side and one bottom edge lugs. the front will then lift of.

Logic comments:	The Clear input (CI) is used to clear an input number, whilst the clear key (C) completely resets the calculator
	Overflow on the input of a number is not suppressed. Keying in a ninth digit results in an overflow which is recoverable using (CI)
	There is automatic constant on all four functions
	The negative sign is shown in the immediate left hand digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers.
	Overflow shows the result an "C" (or "E" if negative") in the far left (ninth) digit and is not recoverable
	A divide by zero error shows zero and "E" in the far left (ninth) digit and is not recoverable.
	There are no obvious bugs.