Unisonic 811

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Calculators: Handheld: Unisonic 811

		Size (approx):	82mm x 134mm x 21-30mm (w,h,d) Weight 132g excluding batteries
		Power:	6V DC, 4 x AAA size batteries. It accepts an adapter/charger (0.4W) through a socket on the top side on the right.
		Case:	Made from a two-piece smooth finish black plastic case with brushed aluminium trim that wraps over all front edges. The slightly recessed keyboard has a similar surround with black printed on/off label. Another small printed plate sits in its own recess in the ridges just below the display and is printed black with company and model name. There is a tilted and proud green display filter that gives a reasonable display. Quite a bold colour scheme for the keys which are squishy, bouncy and long-travel and still work well today. There is a handy calculation example list on the back panel.
		Display:	8 digit green VFD, with a ninth digit for negative and error indication.
		Features:	Standard four functions with percentages and square roots
		Age:	1976
		Manufacturer:	Undefined manufacturer, made in Taiwan, serial No. 043520
		Comments:	Feels more like a small desktop calculator than a hand held with all the metal adding considerably to its weight. Sound logic except for negative square roots. These take over a second to do (longest for 0.9999999) and are lovely to watch as the numbers cycle away. Original soft black plastic case is shaped for the calculator and has a flip over top and front tuck in strap. It is embossed on the rear face with Made in Taiwan.

Components:	1 x cpu: Texas TMS0855NL KAS 7624 (date code week 24 of 1976) 28 pin DIL 1 x 9 digit VFD display flat face single tube. 2 x transistor 3 x diodes 4 x capacitors 5 x resistors 2 x resistor arrays 1 x transformer DCT-04H TDK Japan
Boards:	The keyboard assembly (GICO Japan A5500 1048 GK-187-6) sits above the main cpu board and is joined via 14 stiff wires. The latter has space and labels for more components than are in place. There is a link wire to one of the IC legs on my example - looks like a last minute board design fault.
Construction:	From the rear lever out the two lugs holding the bottom of the calculator out. Carefully pop the side lugs off and the front will detach. It is very easy to overdo it and damage your calculator so be careful.

Logic comments:	(CE) is used to cancel the last number entered and (C) to clear the whole calculator.
	There is automatic constant on all four functions
	Input overflow is suppressed, inputting a ninth digit is ignored
	Negative numbers are shown with a "-" in the far left (ninth) thereby allowing full eight-digit negative numbers
	Divide by zero shows "u” in the far left (ninth) digit and is recoverable using (CE)
	Overflow shows the result with a “u” (“o” if negative) in the far left (ninth) digit and is recoverable using (CE)
	Negative square roots are allowed and result in a negative number

	The manual measures 73mm x 93mm and is printed in black on green paper. It has six fold out pages with basic instructions aimed at a US reader. Printed in Taiwan.