Hitachi KK562a

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Calculators: Desktop: Hitachi KK 562A

	Size (approx):	linked not started 260mm x 310mm x 95mm (max) (w,h,d) Weight 3000g excluding cable
	Power:	Mains (240V 50/60Hz, 8 Watt) power only through a detachable three pin connector.
	Display:	16 digit blue VFD with four additional neon lights on the right for negative (NEG), Error (UDF) and two memory (M1/M2) indicators. Mechanical three-position thousands indicator.
	Features:	Standard four functions with register exchange and four function double memory. Switches for rounding and fixed decimal and constant/accumulator
	Age:	1973
	Manufacturer:	Hitachi Ltd., Tokyo, Japan. Serial number P163123070.
	Comments:	Very heavy and sturdy early 70s desktop that was built to last - and has. Quirky knobs and good bright display adds to the attraction of the Hitachi range of desktops. The fact that there is no floating point mode show how early this machine is. Surprisingly, the logic is not too bad with double memory and register exchange being quite useful and only let down by input overflow. The model KK562 was very similar but replaced the (M2-) function with a square root.

Case and Design:	The base and top section is made of matt black plastic whilst the third display/edge section is matt light grey plastic. The steeply angled neutral display filter is deeply inset to give a clear bright image. A thick plastic embossed label sits on the front edge with the brand and model number printed silver. An almost full width metal handle pulls out from the lower front.
Keys and Switches:	They keys are well laid out, large hollow sounding click with long travel. Two switches to the far left switch on/off and rounding ([5/4] for round and [^/v] for round up/down). There are also two rotary switches. The upper switches between auto memory accumulation and constant. The lower knob switches between zero and nine fixed decimal places, there being no floating point mode. A sliding mechanical indicator is used for the thousands comma with multiple green triangles behind the display filter.

Construction:	Remove the two long screws from the underneath. The whole front section will come off easily, hinging from the top. This then needs to be hinged from the bottom where the main keyboard wires are fixed. A large metal carry handle swings out from the bottom of the base section.
Boards:	The main keyboard assembly (Hitachi HPCB-E-47) is fixed to the front with 12 screws and consist of magnets with reed relay switches. It is connected to the main cpu board by a bunch of 20 wires on an edge connector. The metal rimmed cpu board (Hitachi HPCB-E-147) is fixed to the base by a number of plastic brackets. A third, raised power supply board sits behind the display.
Components:	5 x cpu: Hitachi HD3290P 2M, HD3291P 2L, HD3292P 2L, HD3293P 2L, HD3294P 3A (Nov/Dec 72 and Jan 73), 28 pin DIL, 0.6" width 1 x ICs: Hitachi HD9005 2M 3 x ICs: Hitachi HD3233P 2M/3A 1 x ICs: Hitachi HD3253 2F 1 x ICs: Hitachi HD2901P 3B (Jun/Dec 72, Jan/Feb 73), 16 pin DIL 0.3" width 2 x ICs (I think): 6260 731 1 x IC (I think): 6264 731 16 x single digit VFD tubes and 4 x neon indicators 7 x transistors 33 x diodes 17 x capacitors 68 x resistors 1 x variable resistor 1 x mains transformer 2 x fuses

Logic comments:	(CI) is used to cancel the last number entered and (C) to clear the whole calculator.
	Input overflow is not suppressed, inputting a seventeenth digit is causes an overflow which is unrecoverable
	Constant function is switched in with the "K" switch and operates on multiple and divide only
	The rounding switch can select round down/up [^/v] and round [5/4]
	The decimal point switch can be selected between zero and nine decimal places, but not floating
	Negative numbers are shown with an individual neon light to the right of the main display thereby allowing full 16 digit negative numbers
	Divide by zero shows no display except the error (UDF) neon and is not recoverable, however, when you hot (C) you get 16 zeros!
	Overflow shows the result and the error (UDF) neon and is recoverable (but loses the result) using (C) if the constant function is switched on
	Memory storage is indicated by an individual neon to the right of the main display one of reach of the two memories M1 and M2
	The memory functions are labelled M1, when in fact there is no M2 (or second memory)
	An overflow in memory flags the error and stores the result shifted
	The register exchange key (R) exchanges the answer for the first number entered
	The add and subtract keys are rather archaic RPN. To do 3-4 you input (3)(+=)(4)(-=)
	The memory accumulation switch is also the constant switch. [O] has no function, [S1] sets memory one into auto-accumulation mode; i.e. every (+=) or (-=) key invoking the result of a multiply or divide calculation will add the result to memory one. [K] switches on the constant. [S1K] switches on both as you can imagine. The [S1S2] key auto-accumulates the first number in memory two and the result in memory one.
	It suffers a number of decimal bug: set decimals to [3] and key in (6)(X)(5)(+=) to give "30.000" then use the register exchange (R) and you will find that it recalls "6.000000000000000" instead of "6.000"