Casio H-1

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Calculators: Handheld: Casio H-1

	Size (approx):	77mm (max) x 136mm x 19.7mm (max) (w,h,d) Weight 108g excluding batteries
	Power:	3V DC, 2 x AA size battery, 0.2W. Also accepts adapter (AD-2S). Socket on top side on the left. Manganese batteries last about eight hours whilst alkaline will give 28 hours use.
	Case:	Slim design which fits in the hand well with on/off switch in thumb position on the top left side. Cream plastic base and brown smooth plastic top inset with brushed aluminium panels above display and around keys. Logo and model printed on the top has survived well. Extra switch for decimal rounding control. Display filter makes this a nice blue shade display. Nice design that was to stay typical of Casio for years.
	Display:	8 digit green/blue VFD (no ninth digit)
	Features:	4 function calculator with percentages square root and two function memory
	Age:	1982 - I have a receipt from a different calculator that shows it was sold by W H Smith on 23 January 1982 for £7.95.
	Manufacturer:	Casio Computer Corp. Made in Japan. Serial number 3D706A on inside of battery cover. Model H-1 (B).
	Comments:	You just know this is a Casio!. Only let down by the lack of a ninth digit - hence you can only have seven digit negative numbers and you can have negative roots. A branded version of this was available as the Boots 224. The H-1(B) reference must mean that this was a model revision - I'll let you know when I find an "A".

Components:	1 x cpu: NEC D1877C 8303K9 Japan - 28 pin DIL, 0.6" width 1 x display: Single flat glass tube digitron, eight digit VFD, NEC LD8225 No. 2 Japan 1 x transistor 7 x diodes 7 x capacitors 4 x resistors 1 x transformer
Boards:	Main board (Ref G1G-1(B)) is connected by 16 copper wires to the (and sits on top of the) keyboard board. The latter is secured to the front by 5 screws.
Construction:	Remove the single screw from the back and gently prize from the bottom.

Logic comments:	The (C) button is used to clear last entry of a number and (AC) to clear the whole calculator.
	Overflow on number input is suppressed, typing in a nine digit number ignores the ninth digit.
	An overflow error is flagged with an "E" in the first (right most) digit, negative or positive. Number is not recoverable.
	Divide by zero results in a "E" which is also not recoverable.
	There is constant on all functions by double-hitting the operator.
	Square roots of negative numbers are allowed
	AC cancel the memory as well, there is no indication of memory store - you have to remember it.
	Negative numbers are flagged by a "-" sign in the immediate left digit, limiting you to seven digit negative numbers. If you type in (-)(1)(2)...(8)(=), this will result in an error.

	The box on the left is from a different calculator from the one described above: sold in January 1982. It measures 96mm x 170mm and is 35mm deep. Printed in two colour, black and brown, it is a top tuck end and bottom folded end box. It just states made in Japan.