Casio Mini Memory

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Calculators: Handheld: Casio Mini Memory (light keyboard version)

	Size (approx):	156mm x 82mm x 30mm (w,h,d) Weight 188g excluding batteries
	Power:	6V DC, 4 x AA size batteries. It accepts an adapter (AD-4145, 0.28W) through a socket on the top side about 1cm from the left. The on/off switch has a third position for "T", total.
	Case:	Horizontal format two-piece case in black and white smooth plastic. The display escutcheon in black plastic set in its own recess, flush and tilted. A further inset panel has printed model number and reversed out Casio name on a metallic sticker. Large, long travel hollow sounding keys work well and a deep cut groove (read dirt collection area) outlines the key area. A slightly inset neutral display filter gives a bright display with odd "small zero" notation (see below).
	.Display:	8 digit blue VFD, with no ninth digit for additional display. A shift-display key helps out.
	Features:	4 function calculator with total, percentages and display shift for 16 digit precision. Total summation and decrement facility..
	Age:	1974
	Manufacturer:	Casio Computer Company Ltd. Made in Japan, serial No. 2242964 (on battery cover) and {unreadable} (inside battery compartment).
	Comments:	One of a range of early, solidly built horizontal calculators by Casio very similar to the earlier Casio Deluxe Memory. This one benefits from an eight digit display but strangely keeps the shift key. Logic is let down by unrecoverable errors, divide by zero and quirky memory system. It differs from the dark keyboard model by lack of automatic constant facility.

Components:	1 x cpu: Hitachi HD3654 4K 12, 36 pin DIL (date code October 1974), 28 pin DIL, 0.6" width black plastic 1 x 8 digit VFD display single glass tube: LD8103 2 x transistors 3 x diodes 16 x capacitors 3 x SIL resistor arrays 7 x resistors 1 x transformer: Fuji MPS0603 4I-04 Pat. No. 427559
Boards:	The keyboard board (ref A8Z-E4-1 A) sits lose on top of the battery compartment and is joined to the main cpu board main cpu board (ref A8Z-1B LD8103) by 11 stiff wires. The former is L-shaped to avoid the battery compartment.
Construction:	Remove the single screw on the right hand side and very gently squeeze in the black section to release the lugs one by one. Not for the faint hearted - so do not attempt if you want to keep the calculator pristine.

Logic comments:	The (C) button is used to clear last entry of a number and the (AC) to clear the whole calculator.
	Overflow on number input is suppressed, typing in a seven digit number ignores the seventh digit.
	An overflow error is flagged with the answer displayed and viewable using the shift key (>) and is not recoverable
	Divide by zero error is ignored and calculation can continue with the zero result.
	There is no constant on any function
	To add to the memory switch to "T" mode and every (=) signs adds to the memory. To subtract from the memory use the red (=) key. (AC) clears the memory and there is no indication - you have to remember it.
	Negative numbers are shown by a "-" in the immediate left digit. A result which is eight digits long and negative results in an unrecoverable error but you can see the answer by use of the shift (>) key.

Note the unusual way that zero is represented - by only using the lower half of the digit. Supposedly this format allowed one of the segments in a digit to go out but still allow you to recognise the number.