Sharp Elsimate EL-1103

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Calculators: Handheld: Sharp Elsimate EL-1103

		Size (approx):	79mm x 130mm x 22mm (max) (w,h,d) Weight 122g excluding batteries
		Power:	3V DC, 2 x AA size batteries. Also accepts adapter (EA-17E, 3V, 0.4W) which can be used as a charger through a socket at top side to the far left. Back says use rechargeable battery EA-18B, 2.4V. The on/off switch is on the left hand side in line with the Sharp logo.
		Case:	Slim two piece plastic case, the front being matt dark brown plastic and the back smooth white plastic. A small metallic sticker in its own recess above the display is printed black and red with the company name and model number. Below it sits a lopsided metallic sticker for "Made in Japan". An oversized green plastic display filter is tilted and flush with the case and gives a bright display. The keys are squishy but work well.
		Display:	10 digit green VFD with an eleventh (right-most) digit used for minus and error indictors. Upper commas are used to denote thousands.
		Features:	4 function calculator with percentages, percentage mark-up/down, change sign, total count, square root and four-function memory. Switched decimal place selection.
		Age:	1976
		Manufacturer:	Sharp Corporation, made in Japan. Serial number 65317674 is on a sticker on the inside of the battery compartment.
		Comments:	Typical quality Sharp that fits quite well in the hand especially with the on/off switch at perfect thumb position. Rarer 10-digit model with the uncommon side switch to save space (used also by Casio et al). Odd right hand digit use for indicators is common to Sharp. The logic is not bad with good recovery and useful ten digit functions but let down by a strange memory that does not overflow.

Components:	1 x cpu: Hitachi HD37400 6D31 (April 1976 date code), 42 pin DIL, 0.6" width black plastic 1 x 11 digit VFD; single glass tube flat faced, Futaba 11-ST-24 6C (March 1976) 1 x transistor 7 x diodes 7 x capacitors 3 x resistors 1 x transformer
Boards:	The main cpu board sits on top of the keyboard assembly (held in place with a plastic pillar into a hole) and is joined by an 8-way and 7-way ribbon connector. The keyboard assembly is very sturdy and fixed to the front with one screw. The transformer and side switch assembly have their own holes in the main board to keep the unit as slim as possible.
Construction:	Remove the screw from the inside of the battery compartment. Quite difficult to open without damage. The best way appears to be by levering out the two lugs inside the battery compartment (by using the two slots) to help lever out the top edge and travel down one side. Hinge off the bottom edge and the back will lift off. If in doubt, don't bother.

Logic comments:	The (C.CE) button is used to once to clear the last entry of a number and a second time to clear the whole calculator.
	Overflow on number input is not suppressed, keying in an eleventh digit causes and overflow which is not correctable if the first entry, but is on the second by use of the (C.CE) key
	There is automatic constant on all four functions
	An overflow shows the result and "C" ("E" if negative) in the far right (eleventh) digit and is recoverable using (C.CE)
	Divide by zero shows "0.C" and is not recoverable
	Negative numbers are flagged by a "-" sign in the far right (eleventh) digit thereby allowing full ten digit negative numbers.
	Negative square roots are not allowed and show the result with "E" in the far left (eleventh) digit and is recoverable using (C.CE)
	The (D%) key is used for mark-up and mark-down: to mark up 50 by 10% key in (5)(0)(X)(1)(0)(D%) to give "55", mark down the same amount by (5)(0)(X)(1)(0)(+/-)(D%) to give "45"
	The change sign (+/-) can be used in mid number entry but not before
	The (CT) returns the count of the number of times (=) has been pressed and is cleared by keying (CT) a second time
	Memory store is indicated by a decimal point in the far right (eleventh) digit
	memory overflow is not flagged and stores the result shifted
	A sliding switch allows you to select floating [F] and 4,2,0 fixed decimal digits (with rounding) and [A] financial input mode. The latter causes (2)(3)(4) to be input as "2.34".
	It suffers the Temporary divide to negative zero bug: key in (1)(+/-)(÷)(1)(0)(=)(=)(=) etc until you get to "-0" when one more (=) will leave "0". This shows the extra digit internal precision of the IC.