Commodore GL-996R

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Calculators: Handheld: Commodore GL-996R Custom Green Line

		Size (approx):	78mm (max) x 140mm x 28mm (max) (w,h,d) Weight 162g including in-built rechargeable batteries, 118g without
		Power:	4.5V DC internal sealed batteries. The adapter (type No. DC-420B centre positive, 200mA) is used used to recharge the built in Ni-Cd batteries. The socket is on the right hand side, just above midway.
		Case:	Three piece sturdy case in black and white matt plastic. The top front has an oversized green plastic display filter that is flush with the case an has a sloping inset section. It gives a bright image and it has the Commodore logo raised and painted silver along with the words "Custom Green Line". Bold red, white and blue keys have their own raised surrounds. They keys are wobbly and squishy but work well enough. Below the keyboard is a black printed metallic sticker with the company name, which sits in its own recess.
		Display:	8 digit Green VFD with a ninth digit for negative, and error indicators.
		Features:	Standard four function with percentages and register exchange
		Age:	1975
		Manufacturer:	Commodore Japan Limited. Made in Japan. Serial No. 076051. Ref No. 200503-02
		Comments:	Bold simple design that was to cover many calculators of the Custom Green Line series. The logic is good with good recovery and no detectable bugs in this rather basic but well designed calculator. The rechargeable batteries on my example still worked!

Components:	1 x cpu: Commodore GRBP-89 7527 (week 27 of 1975), 24 pin DIL, 0.6" width 1 x 9 digit VFD, single tube round face 2 x transistor 1 x diodes 5 x capacitors 4 x resistors 2 x resistor arrays 1 x transformer 1 x double AA-sized rechargeable battery pack.
Boards:	The main cpu board (PCB 200432 Art 200433 Rev B) sits on top of the keyboard assembly (HM-20-14-CB HM-18-14-CB KB-6313-12 NEC?) and is held in place with the adapter socket. The two are joined by a long 14-way ribbon cable and the latter is fixed to the front with ten screws.
Construction:	Remove the two screws from the back and then it gets very very difficult to open as the internal lugs on the sides are very tight. Damage is sure to result so I recommend you do not try. There is a white side lug about half way between the bottom and the adapter socket. You need to push the white section in whilst prizing with a blunt wooden or plastic stick. A second on the side, and one on the top start you going around. The rear eventually lifts off. It is just as tricky to get back together again.

Logic comments:	(C) is used on the first press to cancel the last number entered and the second to clear the whole calculator
	Input overflow is suppressed, inputting a ninth digit is ignored
	Negative numbers show a "-" sign in the immediate left hand digit, travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers
	Overflow shows the result and "E" (if positive or negative) in the far left (ninth) digit and is recoverable by continual division by 10 or a multiple
	Divide by zero shows "E00000000" digit and is recoverable by dividing by one
	There is automatic constant on all four functions
	Percentage just divides by zero so can also be used for overflow recovery

The scan to the left shows the man cpu board. The display can be seen well mounted in its two black plastic guides at the top. You can also see the ribbon cable at the bottom of the picture that connects to the keyboard assembly.