Casio FX-11

		Home New Stuff Author Links Guest book Web-log	Adverts Bric-a-brac Calculators Components Ephemera Events	For Sale Glossary History Hit or Miss Radios Transport	Ultra Valves Wanted Metal Puzzles Clocks

Calculators: Handheld: Casio FX-11

		Size (approx):	95mm x 150mm x 30mm (max) (w,h,d) Weight 222g excluding batteries
		Power:	6V DC, 4 x AA size batteries. It accepts an adapter (6V DC 0.45W, type AD-4145) through socket on top side to the far right.
		Case:	Quite a bulky model made from a two-piece smooth white plastic case. A neutral plastic display filter is flat and sits in its own raised section. Below this is a black printed metallic sticker with the brand and model name that sits in its own recess. The keyboard surround is matt black plastic printed with white labels. Keys are long travel, squishy with a soft click and a fast return bounce.
		Display:	8 digit blue VFD with no ninth digit, small zero display (see below).
		Features:	Standard four functions with pi, square root, powers, trigonometric and transcendental functions (with no arc ability)
		Age:	1974 - a sales sticker on the back of my example states “Brown Photo, £49.95”.
		Manufacturer:	Casio Computer Co., Ltd., made in Japan, serial number 2133187 on a sticker on the battery compartment cover and 26003847 on one inside the compartment.
		Comments:	Big chunky early calculator that just fits in the hand. Strange stripped down version of scientific functions with limited accuracy and archaic display notation. Coupled with lack of recovery it is pretty poor really. Oddly reminiscent of the early horizontal series of Casio calculators. One for everyone's Casio collection.

Components:	1x cpu: NEC µPD179C K49406, 28 pin DIL, 0.6" width black plastic 1 x IC: NEC µPD175C E4X086, 24 pin DIL, 0.6" width black plastic (Display driver?) 1 x 8 digit VFD: single tube round front face: 0 x transistors 1 x unidentified: T3184 4F (June 1974) that may be a transistor array, 6 pin SIL. black plastic 3 x diodes 8 x capacitors 3 x resistors 4 x resistor arrays 1 x transformer: Fuji UT0365B Part No. 427559 4I-l4
Boards:	The keyboard assembly (A8N-E4B) sits loose on the battery area and is joined to the main cpu board (A8N-1A) by 14 stiff wires.
Construction:	To open the calculator remove the screw from the rear. This does not really help as the case is held together by internal lugs. The easiest way I found was to push in the rear at the top edge and pop the lug. After popping the side lugs, hinge from the bottom. Be very careful as damage can easily result. Eventually the front will lift off.

Logic comments:	(C) is used to cancel the last number entered and (AC) 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 represented by a “-“ to the immediate left of the number but as there is no ninth digit you are limited to seven digit negative numbers
	Overflow shows only “oooooooo” and is not recoverable
	Divide by zero shows only “oooooooo” and is not recoverable
	Square roots of negative numbers are allowed and result in a positive number
	Transcendental (logs) and trigonometric results are limited to five decimal places
	Power raising is allowed for positive integers only and doesn’t require and equals key press: i.e. 2⁸ is keyed in as (2)(aⁿ)(8) where n = int(>0)
	Pi is held to six decimal places only

	This scan with the front removed shows the main board but hides the cpu underneath the the blue keys. The secondary display driver IC can just be seen under the display tube. Plenty of component labels on this early board less than the normal quantity of components for its age due to the numerous arrays used.
	This image shows the small zero notation of the display. I believe that this format was invented so that if any one segment was out you could still tell what the number was. This idea wasn't to survive past 1975 though.