Lloytron Accumatic 20

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Calculators: Handheld: Lloytron Accumatic 20 (aka EH-8822-2)

		Size (approx):	92mm x 140mm x 29mm (max) (w,h,d) Weight 164g excluding batteries
		Power:	6V DC, 4 x AA size batteries. Accepts an adapter (6V DC 250mW, series 255B, centre positive) through socket on top side to the far right. The on/off switch is located on the top side in the middle.
		Case:	Made from a three-piece case, the lower section is smooth dark brown, the middle is smooth beige and the front is matt dark brown. A neutral plastic display filter is flat and flush and has the model number printed in white text. Below this is a black printed metallic sticker with the brand name that sits in its own recess. Keys are squishy but work very well with a fast return bounce. Extensive example panel on the back.
		Display:	8 digit blue VFD, with a ninth digit for minus memory and error indicators
		Features:	Standard four functions with change sign, percentages, register exchange and four function memory
		Age:	1975
		Manufacturer:	Lloytron, Model EH-9036-2 made in Japan, serial No. 1-17665.
		Comments:	Sits comfortably in the hand with nice smooth sides, but slightly oversized basic calculator. Archaic colour scheme for the keys fits with the brown and orange themes of the 1970s. The logic is average with good recovery but numerous bugs let it down - though mine may be malfunctioning. Original black soft plastic case has wrap over and tuck in flap and embossed "Made in Japan" on front.

Components:	1 x cpu: IDT (I think - circular integral sign) LC1552-B 7509 (week 9 of 1975), 40 pin DIL, 0.6" width black plastic with black cap 1 x 9 digit single tube VFD display round face 2 x transistors 6 x diodes 6 x capacitors 1 x resistor array 5 x resistors 1 x transformer: Zebra DCT-04
Boards:	The keyboard (Gico 1552B Japan)(50.4.6 which is date code 6th April 1975) is joined to the main cpu board (IL-15) via a row of 10 stiff wires. The whole subassembly floats free in the case.
Construction:	Use the coin slot in the top to gently prize apart the case. Start with the top then right hand side by squeezing in the brown back to release the lugs (one on either side, two on top and bottom). The front then lifts away.

Logic comments:	(C/CE) is used to once to cancel the last number entered and a second time to clear the whole calculator.
	There is automatic constant on all four functions
	Input overflow is suppressed, keying a ninth digit is ignored
	Negative numbers are shown with a "-" sign in the immediate left hand digit, travelling into the far left (ninth) digit to allow full eight digit negative numbers
	Divide by zero shows zero and "C" in the far left (ninth) digit and is recoverable using (C/CE)
	Overflow shows the result and "C" (or "E" if negative) in the far left (ninth) digit and is recoverable using (C/CE)
	You can use the change sign function in mid number entry and before
	Memory store is indicated by the decimal point in the far left (ninth) digit
	Overflow in memory is indicated and the shifted result is stored
	(EX) is a register exchange, swapping the displayed number for the last entered in a chain
	The percentage key divides by 100, repeatedly. If you use it too many times you will get an inverted "C" in the far left (ninth) digit which is recoverable using (C/CE)
	I suspect there is something wrong with my sample as I cannot calculate to zero: i.e. (1)(-)(1)(=) gives "1", can anyone help?
	It suffers the divide to negative zero with trailing zeros bug: key in (1)(+/-)(÷)(1)(0)(=)(=)(=) etc to eventually get "-0.0000000"
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to get "1.000" which remains a fixed three digit decimal number until you need more digits or use multiply or divide

With the front removed you can see the common method of layout used on Lloyd's / Lloytron calculators that can also be seen in Decimo and many other machines. The GICO keyboard sits over half of the main cpu board and rests on the inside of the battery compartment.

You can only just see the corner of the large and uncommon LC1552-B IC.