Sanyo CX-8133

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Calculators: Handheld: Sanyo CX-8133


			Size (approx):	85mm x 147mm x 31mm (max), 33mm with cover (w,h,d) Weight 160g excluding batteries and cover (192g with cover)
			Power:	3.0V DC, 2 x AA size batteries. It accepts an adapter (2.8V DC, 0.3W type CU-20) through a socket on the top side to the far left.
			Case:	The main wedge shaped body is made from black and buff matt plastic with an additional slide on buff matt plastic full front cover. The cover has Sanyo Mini Calculator embossed on the front and open directions either lower side. The front is completely covered by a wrap over edge a brushed aluminium panel. Embossed in the panel is a black printed logo with a printed model number below. Similarly the on/off switch has black printed text. A slightly inset and tilted green plastic display filter has digit numbers embossed above the display. The large keys are short travel and very squishy with a soft click. The rear of the case has embossed examples. There is a swivelling plastic tag at the top for a carry strap and two springy plastic prongs on either side that lock the front cover.
			Display:	8 digit green VFD with a ninth digit for negative, error and memory indicators
			Features:	Four standard functions with percentages, square root, change sign and three function memory
			Age:	1976
			Manufacturer:	Sanyo Electric Company Ltd., made in Japan, serial number 04304286T.
			Comments:	Works well in the hand or on the desktop due to the pronounced wedge shape. Innovative slide up cover does a good job of protecting the metal fascia and also has a novel auto-off feature (see below). The logic is quite good but let down by lack of recovery and a strange zero percentages.

Components:	1 x cpu: NEC µPD277C H57646, 28 pin DIL, 0.6" width black plastic 1 x nine digit VFD tube, flat face single tube: Futaba 9-ST-08 6B (February 1976) 2 x transistors 5 x diodes 9 x capacitors 7 x resistors 2 x resistor arrays 1 x transformer: 246
Boards:	The main cpu board (R-4170782 B-1) sits on top of the keyboard assembly (13082E), held in place by two plastic lugs and two glue points on the display. The two are joined by a short 17-way ribbon cable.
Construction:	Remove the screw from within the battery compartment. Pop the side lugs by pushing in the rear of the case. The rear will lift off easily, hinging at the bottom then hinging to the left as the power cables are attached to the main board.

Logic comments:	The (C) key is actually a “CE/C” key; the first press can be used to clear the last entry whilst a second press clears the calculator completely
	Input overflow is suppressed, keying in a ninth digit is ignored
	Negative numbers are represented with a “-“ sign in the far left (ninth) digit thereby allowing full eight digit negative numbers
	There is automatic constant on multiply and divide only
	Overflow shows the result with “C” (or “E” if negative) in the far left (ninth) digit and is not recoverable
	Divide by zero shows zero and “C” in the far left (ninth) digit and is not recoverable
	Memory store is operated by the (M=) key which is actually a (M+) key as subsequent press add to the existing contents. Hitting (-)(M=) will decrement from memory. (MRC) will recall the memory whilst a second press clear the memory
	Memory store is indicated by the decimal point of the far left (ninth) digit
	Overflow in memory maintains the original number
	The percentage key, if used in isolation, will repeatedly divide by 100.
	There is a bug that allows you to do this on zero: key in (C)(%) to get “0.00”, (%) will give “”0.0000”
	Negative square roots are not allowed and it shows zero and “C” in the far left (ninth) digit and is not recoverable
	No other bugs found

Auto switch off

This image shows the automatic switch-off feature. The inside of the cover contains a small ledge (approximately 10mm) that forces the on/off switch to the off position as you slide up the cover.