Sharp Elsimate EL-201S

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Calculators: Handheld: Sharp EL-201S (Elsimate)

		Size (approx):	75mm x 120mm x 22mm (max) (w,h,d) Weight 118g excluding batteries.
		Power:	3V DC, 2 x AA size batteries. It accepts an adapter (EA-17E, 3V DC, 0.2W) through a socket on the top side to the far left. The on/off switch is recessed on the left hand side, just above the display.
		Case:	Wedges shaped, two-piece plastic case in matt blue and gloss white (or possibly very light grey) plastic. The top area houses a black and red printed metallic sticker that sits in its own recess and bears the brand name and model number. The word Sharp is printed below in white text. The inset and tilted green plastic display filter has its own white printed, raised escutcheon. The keys are soft and squishy with a "levered" action, identified by white printed text and bordered with grooves.
		Display:	8 digit green VFD with a ninth digit (on the right) for negative, error and memory indicators.
		Features:	Four function with percentages, square roots and one function memory
		Age:	1977
		Manufacturer:	Sharp Corporation, made in Japan, serial number 76259552 on a sticker inside the battery compartment. Stig from Sweden has a black version with serial number 66219017 (the difference is over 10 million - did they really make this many or did different colours start at different numbers?).
		Comments:	Stylish slim calculator with a nice colour scheme but clashing green display (blue would have been better). The logic is fine with good recovery but let down by the negative zero bugs. The one key memory is also a bit awkward. Well built - typical of Sharp.

Components:	1 x cpu: Hitachi HD37332 7B13 (date code February 1977) 28 pin DIL , 0.6" width, black plastic 1 x nine digit VFD unit flat faced single tube 2 x transistors 4 x diodes 2 x resistors 4 x capacitors 1 x transformer
Boards:	The main cpu board (F1420) sits loosely on top of the keyboard assembly and is joined by a 16-way ribbon cable. The latter is attached to the front with a couple of plastic lugs.
Construction:	Remove the screw in the battery compartment. It is then quite difficult to open as there are two internal lugs on the top and bottom edge and one on each side. You have to try and push in the rear section. It is quite tricky so be warned - damage can easily result. I found it easiest to start with the top side and work around. The rear eventually lifts off.

Logic comments:	The (C/CE) key is used to cancel entry on the first press and clears the whole calculator on the subsequent. Two presses are needed to clear the total memory function.
	Overflow on the input of a number is suppressed, typing in a ninth digit is ignored
	There is automatic constant on multiply and divide only
	Negative numbers are flagged by a "-" sign in the far right (ninth) digit thereby allowing full eight digit negative numbers.
	A divide by zero shows zero and "C" in the far right (ninth) digit and is not recoverable
	Overflow shows the result with "C" ("E" if negative) in the far right (ninth) digit and is recoverable using (C/CE)
	There is a one function memory. Using (M) will recall the total accumulation of every number that results from an equals key. Press (M) twice to clear it.
	The Memory store is indicated by the decimal point of the far right (ninth) digit
	Negative square roots are not allowed and show the result with an "E" in the far right (ninth) digit and is not recoverable
	This calculator suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" now key in (+)(1)(=) to give "-0"
	Also it suffers the reduced to negative zero bug: key in (1)(-)(2)(=) to give "-1" now key in (/)(1)(0)(=)(=) etc until you get "-0"

	With the back removed you can hinge out the main cpu board by removing the adapter socket/battery terminal/switch unit from its guide. The very small board is well built with metal clasps holding the thin-film keyboard connector and display. The board has a strange saw-tooth edge, the first slot being used to guide it into place in the front of the case.