Sharp Elsimate EL-8000R Red

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Calculators: Handheld: Sharp Elsimate EL-8000R (red and black)

		Size (approx):	85mm (max) x 137.5mm x 26mm (max) (w,h,d) Weight 146g excluding batteries
		Power:	6.0V DC, 4 x AA size batteries. Also accepts an adaptor (EA-14A or EL-97, 1.4W) through top side socket on the right, 0.4W.
		Case:	Unusual two-piece plastic case in red smooth and black matt plastic. The whole thing is shaped rather like a pint glass but fits in the hand quite comfortably. There is a very large green display filter that wraps over the top and gives a nice bright image. A metallic sticker printed black and red sits in its own recess in this filter. The keys are short travel and squishy but work rather well. They are labelled with engraved shapes painted black.
		Display:	8 digit green VFD with a ninth digit for negative and error indicators.
		Features:	Four function plus percentages and square root.
		Age:	1975
		Manufacturer:	Sharp Corporation, Made in Japan. Serial number 51065412 on a sticker inside the battery compartment
		Comments:	Basic calculator that was obviously a design experiment, as no one copied it and its successor went back to normal. A Cream and Brown version was also available. I think this is cream rather than originally white as the inside of the case is the same colour. The logic is poor with no recovery and both negative zero bugs. I think that the "R" suffix may refer to the square root function.

Components:	1 x cpu: Hitachi HD36290 5B 21 (February 1975), 28 pin DIL 0.6" width black plastic 1 x 9 digit VFD; single tube round faced 1 x transistor 6 x diodes 9 x capacitors 7 x resistors 1 x resistor arrays 1 x transformer: TDK 1247 Japan
Boards:	The main cpu board (F1226CC-A) is held in place by two plastic lugs and a screw above the keyboard assembly. The keyboard is attached to the front with one screw and to the main board with a 14-way ribbon cable. The back of the keyboard assembly forms the inside of the battery compartment. There is a large piece of matt black paper around the display tube to cut out stray light.
Construction:	Remove the screw from within the battery compartment and push out the lug that is clearly visible at the bottom of the compartment. This is more difficult than it sounds so be very careful not to damage your calculator. The whole back the lifts off, hinging from the top. The back is stamped inside with "50.1.8" which may be a date code (if so, the 8th January 1975).

Logic comments:	The (CE) key clears the last number entered whilst (C) clears the whole calculator
	Input overflow is suppressed, inputting a ninth digit is ignored
	There is automatic constant on multiply and divide only
	Negative numbers are shown by a "-" displayed in the far right (first) digit thereby allowing full eight digit negative numbers
	Divide by zero result in the display of "0.C" and is not recoverable
	Overflow results in the display of the result and "C" (or ending in "E" if negative) in the far left (ninth) digit and is not recoverable
	Square roots of negative numbers are not allowed and show the result and "E" in the far left (ninth) digit and is not recoverable
	It suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" then (+)(1)(=) to give "-0"
	It also suffers the negative divide to zero bug: key in (1)(-)(=) to give "-1" then (/)(1)(0)(=)(=)(=) etc to eventually get "-0", one more (=) gives "0"

This image shows the back removed. The main cpu board is fixed with two lower plastic lugs and an upper central screw. The keyboard assembly board below it also doubles as the battery connection system, the terminals being connected directly to it.