Hanimex BCM30

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Calculators: Handheld: Hanimex BCM30


		Size (approx):	74mm (max) x 132mm x 21mm (max) (w,h,d) Weight 90g excluding batteries.
		Power:	9.0V DC, 1 x PP3 size battery. Also accepts adapter (undefined) through a top side socket to the far right.
		Case:	Two-piece matt brown plastic case with a op section big enough to accommodate a nine volt battery. The top area has a slightly recessed brushed aluminium panel with black printed text for the brand and model number. A shaped red plastic display filer is sloped in its own escutcheon. It gives a bright display but with limited angle viewing. The keyboard surround is beige smooth plastic with embossed "on" label for the switch. The keys are short travel with a pronounced click in typical 70s orange and dark brown.
		Display:	8 digit red LED with individual bubble lens and no ninth digit
		Features:	Standard four function with percentages, change sign and four-function memory
		Age:	1976
		Manufacturer:	Made in Hong Kong, no serial number as the sticker in the battery compartment was unreadable in my example.
		Comments:	Unusual Hanimex with a cheap-looking case and typical 70s colour scheme. The logic is really let down by a lack of a ninth digit even though the IC can manipulate eight digit negative numbers. Lack of memory indicator (may be the same problem), memory loss on overflow and pseudo fixed decimal bug all add up to a poor job.

Components:	1 x IC: Texas ZA0571 KFR 7620 (week 20 of 1976), 28 pin DIL, 0.4" width black plastic 1 x 8 digit red LED module: National Semiconductor NSA1188 624 0 x transistors 0 x diodes 2 x capacitors 3 x resistors
Boards:	The main board sits face up on top of the keyboard assembly and is held in place by four plastic clips. Connection the the keyboard is via a 15-way collection of wires held by a small plastic former.
Construction:	Very difficult to open as this is held together by internal lugs only and the sides are so stiff and tight fitting that damage is very likely to result. If you really must try, I found the best way was lever apart the edge from within the right side of the battery compartment first and travel down that side. And that doesn't help much! The rear section will eventually lift off.

Logic comments:	(CE) cancels the last number entered whilst (C) will clear the whole calculator
	Input overflow is suppressed; inputting a ninth digit is ignored
	There is automatic constant on all four functions
	Negative numbers are represented by a "-" sign in the immediate left digit but as there is no ninth digit to travel in it only displays seven digit negative numbers. Eight digit negative numbers are allowed but you cannot tell if its negative!
	Overflow shows the result flashing and is recoverable using (CE)
	Divide by zero shows zero flashing and is recoverable using (CE)
	Memory store is not indicated - you have to remember it
	Overflow in memory flags the error and zeros the memory
	Change sign can be used in mid number entry and before
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to give "1.000" which remains a three digit fixed decimal number until you need more digits or use multiply or divide

This image shows the calculator with the rear section removed. Most basic construction with few components to keep the costs to a minimum.

The board is held very tightly by four plastic lugs on the sides which look like they could not be bypassed without breaking them.