Plustron Educational 1

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Calculators: Handheld: Plustron Educational 1

		Size (approx):	72mm x 133mm x 21mm (max) (w,h,d) Weight 108g excluding batteries
		Power:	3V DC, 2 x AA size batteries. It accepts an adapter (3V centre negative, 0.25W) through a socket on the right side in line with the (C) key.
		Case:	Roughly wedge shaped case in black matt and (originally) white glossy plastic. The brand and model, along with some graphics are printed in black text on the top section. A convex blue plastic display filter gives a clean bright image. They keyboard surround is white painted plastic with additional lettering in black. They keys are medium travel with a plastic sounding click. This example is badly UV light-yellowed.
		Display:	10 digit blue VFD where the third digit is a seven segment symbol cluster and the sixth is an equals sign
		Features:	Basic four function two digit calculator and three educational game modes.
		Age:	1978
		Manufacturer:	Plustron, made in Taiwan, serial number 00933, part number 943106.
		Comments:	Unusual deviation from the standard calculator with an attractive colour scheme and great display. However, the two digit calculator is pretty useless, the level 1 problems suitable for children, the level 2 are too hard (do you know what 57 X 64 is off the top of your head?) and multiplication tables too limited. The original case is soft black plastic with an open top and half-moon cut-outs either side.

Components:	1 x cpu: NEC D1022C E83066 (estimated date code of 1978), 28 pin DIL, 0.6" width black plastic 1 x 10 digit VFD unit, single glass tube flat faced: NEC FIP LD8229 7K (date code October 1977) 2 x transistors 6 x diodes 6 x capacitors 3 x resistors 1 x transformer: Apollo CV-001
Boards:	The keyboard assembly sits lose on top of the cpu board and is connected by 15 short strong copper wires. The main board is held in place to the rear with some plastic guides.
Construction:	Difficult to open as it is held together by internal plastic lugs only. Damage is likely so if in doubt, do not attempt. The easiest way I found was to pop the top lugs first by pressing in the black rear section - but watch out as the top area is very thin. The front will eventually lift off.

Logic comments:	The (C) button is used to clear the machine completely there being no (CE) function
	Switched functions between: A - 2 digit calculator B - Level 1 problems C - Level 2 problems D - Multiplication table
	In calculator mode it operates as a two digit machine with arithmetic display. On start up the symbol cluster is fully alight. Keying in (5)(/)(2)(=) will show "5 ¸ 2 = 2.5". The third digit can also display an "X", "-" and poor looking "+". Answers can be up to four digits long with a maximum of three decimal points.
	Overflow is impossible
	Divide by zero shows "1 ¸ 0 = EE" and is not recoverable
	In educational mode start up shows a flashing fully lit symbol cluster.
	In mode B and C you start by pressing the operator of choice: thus by pressing (+) you get ten additional sums presented and key in the answer - and wait a couple of seconds. If the answer is wrong a "EE" is displayed and you get another go. If the answer is a two digit result and you key in the incorrect first digit it goes straight into error mode. Two wrong guesses and you are given the correct result. At the end of ten questions you are shown a score like "10:7 0" where I think the third digit is the number of second guesses correct. Pressing (T) at the end will give you a running game count and total.
	In mode D you start by pressing the key of the multiplication table you want: key in (5) and it asks you "5 X 0 =" then "5 X 1 =" etc up to times nine. You can only do zero to nine times table.