Kovac LE-802

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Calculators: Handheld: Kovac LE-802


		Size (approx):	72mm x 140mm x 32mm (w,h,d) Weight 170g excluding batteries.
		Power:	9V DC using 6 x AA size batteries. Also accepts adapter/charger (DC 9V undefined but centre negative) through a top side socket on the far left. There is a battery check function: hold down the (+=) key and if only the decimal point shows then change batteries. There is also a power save function: after about 10-15 second the display switches off, to recall press (+=).
		Case:	Quite thick calculator made from three pieces of light and dark grey matt plastic. There is a large purple plastic display filter which is slightly inset and tilted. Below this is a black printed metallic sticker with the brand name that sits in its own raised recess. There should be a similar label around the three switches which is missing in this example. The stepped keys are very squashy but work well enough. The rear holds a large metallic sticker with black printed instructions and an extra panel for a name label.
		Display:	8 digit red LED (large format) with a ninth digit for input overflow, negative and error indicators.
		Features:	Four function with switched constant and fixed decimal modes. RPN logic.
		Age:	1973
		Manufacturer:	Made in Japan, serial number 0319656
		Comments:	Fabulous! Early and rare example of a strange calculator that uses six batteries, two component boards and unusual large format LED units. Not bad logic that is only let down by archaic RPN, input overflow and lack of recovery. However, this example is missing its label for the front switches. The three switches from left to right are "K", "F/2" and "On/Off"

Components:	1 x cpu: Texas TMS0105BNC 7309 (week 9 of 1973) 28 pin DIL , 0.6" width black plastic 2 x ICs: Texas SN75491N 7301J, 14 pin DIL, 0.3" width black plastic 2 x ICs: Texas SN75492N 7301J, 14 pin DIL, 0.3" width black plastic 9 x 1 digit red LED, large format flat fronted units 11 x transistors 3 x diodes 10 x capacitors 16 x resistors 1 x transformer
Boards:	The main cpu board (LE-8C-C) is held in place by six plastic guides and is attached to the keyboard assembly (K305765 A024731) via 16 coloured wires. The main board sits above a secondary board (LE-8C-D) stuffed full of components. They are separated by a shaped piece of black card. The secondary board sits loose in the case and is connected by eight coloured wires.
Construction:	Remove the two screws at the rear. This does not help much as the case is held together by internal lugs and the case sides are rather stiff. Easy to damage you example so be very careful. The best method I found was to prize apart one of the sides by using a fingernail and pushing in the light grey rear section. Then prize apart the top in the same way to release the front case section.

Logic comments:	The (CE) key is used to clear the last entry and the (C) key clears the whole calculator
	Overflow on the input of a number is not suppressed, typing in a ninth digit results in "C" in the far left (ninth digit) but calculations can proceed with the significant eight digits
	There is selectable constant for multiply and divide only by using the middle (K) switch in the up position
	Negative numbers are flagged by a minus sign in the far left (ninth) digit thereby allowing full eight digit negative numbers.
	The left switch limits the answers to two decimal places when up
	Overflow shows the result and "u" (or "o" if negative) in the far left (ninth) digit and is not recoverable
	Divide by zero shows zero and "u" in the far left (ninth) digit and is not recoverable
	The logic is Reverse Polish notation: to key in 4-5 use (4)(+=)(5)(-=)
	There is a power save function when the display goes to a decimal point in the first digit only and is recovered by the (+=) key: my example took 15 seconds to gently fade away
	No bugs found


This scan shows the front removed and the main cpu board with the five Texas chips and rare early LED displays. These give as good an image as the early Panaplex orange displays, with a wide angle of view.		And this scan shows the cpu board (and black card insulator) removed, exposing the crammed component board.