Sinclair Cambridge Universal

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Calculators: Handheld: Sinclair Cambridge Universal

		Size (approx):	50mm x 100mm x 18mm (23mm battery cover area) (w,h,d) Weight 46g excluding batteries
		Power:	9V DC, 1 x PP3 size battery. It does not accept an adaptor/charger.
		Case:	Two-piece smooth white plastic case which is designed so small that the 9V battery compartment protrudes out an extra 5mm! A raised escutcheon frames a deep purple display filter that gives quite a good, if narrow view of the digits. The keyboard surround is in contrasting black plastic. The white keys are short travel and give a prominent click but work well enough. Some of the black printing on the keys has worn by the white printed key labels have faired better. The company and calculator name are printed in black.
		Display:	8 digit red LED with bubble lens with no ninth digit.
		Features:	Four functions plus percentages, square root, squares, reciprocal and five function memory.
		Age:	1977
		Manufacturer:	Sinclair Radionics of Cambridge, UK, made in England, serial No. (sticker in battery compartment) 703167.
		Comments:	A classic early pocket calculator famous for its affordability and small size. The Cambridge range was also available in kit form to cut the cost of ownership even more. Not all the range used the strange humped-back battery compartment idea - thank goodness! A must for everyone's collection. Original case is soft black plastic with flip over flap and front tuck in band. With such a weird calculator shape it is never going to look right. Uses the same IC as the Cambridge Memory, with some functions not accessible.

Components:	1 x cpu: Mostek MK50321N Malaysia 7712 (date code week 12 of 1977), 28 pin DIL, 0.6" width 1 x 9-digit miniature LED with bubble lens display embedded in the board; National Semiconductor Z013 no other components
Boards:	One board that houses the keyboard assembly and main cpu assembly sits lose in the case.
Construction:	Lugs hold the two sides together all around - three on the sides and one each top and bottom. High potential for damage trying to open it so beware.

Logic comments:	(C/CE) is used to clear once to the previous number entered and a second time to clear the whole calculator.
	There is automatic constant on all functions but you must enter two digits for it to work on plus and minus; i.e. (5)(X)(=) gives "25" but 5(+)(=) does not work.
	Input overflow is suppressed, inputting a ninth digit is ignored
	Negative numbers are shown with a "-" in the immediate left digit but as there is no ninth digit to travel into you are limited to seven digit negative numbers.
	Divide by zero shows a flashing "0." and is recoverable using (C/CE)
	Overflow shows the result flashing and is recoverable using (C/CE)
	Negative square roots are not allowed and result in the original number flashing. It is recoverable using (C/CE).
	Memory store is not indicated; you have to remember it. You can also store the result part of an error in memory.
	The (F) or function key is used to select the operation in the upper label