Casio Personal M-1 H-813C

		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 Caravan

Calculators: Handheld: Casio Personal M-1 (aka H-813C)

	Size (approx):	75mm x 125mm x 20mm (max) (w,h,d) Weight 96g excluding batteries.
	Power:	3.0V DC with 2xAA size, 0.2W. Also accepts adapter (AD-2S) through top side socket on the far left. The on/off switch is on the left side just above the Casio logo.
	Case:	Two -piece case in white and black plastic of a square design with rounded edges. The neutral display filter is slightly tilted and gives a clear bright image. Above the display a black and blue printed brushed aluminium sits in its own recess. The keys are typical Casio, long travel and squishy but work well on all my examples.
	Display:	8 digit blue VFD fluorescent display with no ninth digit
	Features:	Four function with square root, percentages and one function memory
	Age:	c1981/2
	Manufacturer:	Casio Computer Co. Ltd. Made in Japan. Serial number is printed on the battery compartment cover 2K106A.
	Comments:	Compact little calculator with basic functions and auto-accumulating memory. This model was a revision of the earlier Casio H-813 and Casio H-813B. This "C" revision does not appear to have many changes; same chip and a few less components. The logic is sound enough but the lack of ninth digit is annoying and the memory too basic to make much use of. The manual included with my example is referenced H-813B, so it may be the wrong manual or they may not have updated it – can anyone verify that there is a “C” version of the manual?

Components:	1 x processor NEC D1877C E21069, 28 pin DIL, 0.6" width 1 x 8 digit VFD glass flat fronted, LD8225 4 x resistors 8 x capacitors 5 x diodes 1 x transistor 1 x TC-11 (TDK) transformer
Boards:	One main board (G183-1A) with few components and second keyboard board joined by 14 strong copper connectors which can be hinged out. The latter is held to the front with four screws.
Construction:	Remove the screw inside the battery compartment. It is quite difficult to then pop the top (by pushing a blunt instrument through he gap in the battery compartment), Then gently pop the right side whilst skewing the rear section away from the on/off switch and gently hinge from the bottom. The rear will then lift off. If in doubt - do not try it. Adaptor socket tends to come lose which makes reassembly a little more difficult.

Logic comments:	The Clear key (C) is used to clear an input number, the all-clear (AC) to completely reset the calculator.
	Overflow on the input of a number is suppressed, typing in a ninth digit is ignored
	The constant function is invoked on all four functions by double pressing the operator, i.e. (3)(+)(+)(=) gives "6" (=) gives "9" etc.
	There is no indication of memory use - you have to remember it.
	The negative sign is to the immediate left of a number, but as there is no ninth digit to travel into you are limited to seven-digit negative numbers
	On overflow the display shows most of the result and "E" in the far right (first) digit and is not recoverable.
	On divide by zero the display just shows "E" in the far right (first) digit and is not recoverable.
	Negative square roots are allowed and result in a negative number
	The memory automatically accumulates all numbers that result when the (=) key is pressed. (AC) also clears the memory.

box

The box measures 78mm by 150mm and is 26mm deep. It is printed in green and black and is top/bottom flap construction. There is no information of origin except the made in Japan text. The top and bottom flaps have the reference number H-813C