Casio J-3

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Calculators: Handheld: Casio J-3 (aka J-1211)

	Size (approx):	100mm x 160mm x 23mm (max) (w,h,d) Weight 184g excluding batteries
	Power:	3V DC, 2 x AA size battery, 0.32W. Also accepts adapter (AD-2S). Socket on top side on the left.
	Case:	Large desk-top sized calculator that just about fits in the hand. Two-piece cream and very dark brown smooth plastic case. Large brushed aluminium keyboard surround printed with black text. Large square keys with typical Casio black plastic escutcheons. They are squishy but work very well. Slightly titled neutral display filter gives a clear display. Raised panel has silver printed logo and name and has survived well on this example. What a big one! On/off switch has a printed green indicator. There are two other switches for floating/round down/round and 4/2/1/0 decimal places.
	Display:	12 digit blue VFD (with a thirteenth digit for minus, memory and error indication) with thousand separators.
	Features:	4 function calculator with percentages, delta percentage, square root, change sign and three function memory
	Age:	1978
	Manufacturer:	Casio Computer Co., Ltd. Made in Japan. Serial number (in battery compartment) 0266690.
	Comments:	You just know this is a big Casio!. Very large, very robust and unusual 13 digit display, obviously aimed at the office market. Quite good logic but a few annoying bits. My example has a whistling display driver and must eat batteries like a hungry volt-monster from EverChomp. Now for something really weird; if you carefully lift up the sticker showing the model number you will see the Casio J-1 text embossed beneath it. Was this a generic back panel in excess stock? I suspect so as my J-1 has the same back.

Components:	1 x cpu: Hitachi HD38401A 8M15 (I think this is the 15 Dec 1978) 36 pin DIL 1 x display: 13 digit single flat glass tube; NEC F1P 2 x transistor 7 x diodes 8 x capacitors 5 x resistors 1 x transformer; 8X TC-19 TDK
Boards:	Keyboard board is secured to the front via 5 screws and four plastic lugs. It connects to the main cpu board (Ref. B12Y-1A) via 24 stiff copper wires with an insulating strip. There is also a ground wire to a large shield panel stuck to the back.
Construction:	Remove the two screws from the back and then what! Not for the faint hearted this one. You need to squeeze in the upper case side which is practically impossible as it is so stiff. When the lugs are popped hinge off from the bottom. It took me 15 minutes. If you do not want to damage your calculator I would recommend you do not open it.

Logic comments:	The (C) is used to clear last entry of a number and (AC) to clear the whole calculator.
	Overflow on number input is not suppressed, typing in a thirteen digit number cases overflow which is not recoverable - annoying!
	An overflow error is flagged with an "C" ("E" if negative) in the thirteenth (left most) digit and is recoverable using the (C) key
	Divide by zero results in a "C" in the thirteenth (left most) digit which is not recoverable.
	There is automatic constant on all functions
	Square roots of negative numbers are not allowed but the answer is shown and it is recoverable using the (C) key
	Memory store is indicated by a decimal point in the thirteenth (left most) digit
	Negative numbers are flagged by a "-" sign in the thirteenth (left most) digit thereby allowing full twelve digit negative numbers
	There is a switch "F Cut 5/4" for floating, round always down and round
	There is also a switch to set the number of decimal places 4/2/1/0
	The change sign key will operate on the displayed number even after a function button is pressed - also annoying!
	The (delta %) key can be used to add the percentage (i.e. mark-up); (9)(X)(6)(D%) displays "9.54" or mark down; (9)(x)(6)(+/-)(D%) gives "8.46"