Hanimex BC900 type II

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Calculators: Handheld: Hanimex BC900 (type I)

		Size (approx):	83mm x 135mm x25mm (w x h x d) Weight 144g excluding batteries.
		Power:	6.0V DC using 4 x AA size batteries. Can accept an adapter/charger through a socket on the top side to the far left. There is a power save mode after around 25 seconds.
		Case:	It is a very sturdy two-piece white and black matt plastic case with a middle metallic plastic strip. A brushed aluminium keyboard surround has some printed black text labelling on the on/off switch and reminding you it’s a calculator! A slightly proud but flat oversized, wrap-over green display filter gives a clear, deep image. It has white printed boarder and model text. The keys are short travel, loud click type and nearly flush with the calculator. The colour scheme is somewhat bold!
		Display:	8 digit green VFD with a ninth digit for negative and error indication
		Features:	Standard four functions with percentages and display recovery
		Age:	1975/6
		Manufacturer:	Back panel on my example is too poor to read. The serial number is inside the battery compartment E-6 136851. There is also a QC inspection sticker 601.
		Comments:	Very solid calculator with nice deep-seated green display. Keys are rather unreliable. Logic whilst basic is very sound with good recovery characteristics and only let down by the pseudo fixed decimal bug. The original case is soft black plastic with Hanimex embossed on the front. It has a flip over top and popper front closing. Compare with the later BC900 type II.

Components:	1 x cpu: Texas TMS0851NC 7546 (week 46 of 1975), 28 pin DIL 0.6" width 1 x 9 digit VFD unit, single glass tube flat faced 2 x transistors 4 x diodes 10 x resistors 1 x resistor array 5 x capacitors 1 x transformer
Boards:	The keyboard assembly is a PCB (KA-1-9000511 S19CT) with metal click-pads and is soldered to the battery terminals. The keys remain in place on the front section of the calculator. This PCB is attached to the main cpu board with 18 wires.
Construction:	Held together by internal lugs only so be careful not to damage on opening. I found the best way was to push in the front side section to try and pop/lift of these lugs. The front will eventually lift off with the keys in place.

Logic comments:	The (CE/C) key is used to once to clear the last entry and a second time clears the whole calculator
	Input overflow is suppressed, keying in a ninth digit is ignored
	There is automatic constant on all four functions
	Negative numbers are indicated by a “-“ in the immediate left digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers
	Overflow shows the result and “C” (“E” if negative) in the far left (ninth) digit and is recoverable using (CE/C)
	Divide by zero shows zero and “C” in the far left (ninth) digit and is recoverable using (CE/C)
	After 25 seconds the calculator goes into power save mode with just the “-“ segment of the far left (ninth) digit on. Recovery is by pressing (D)
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to give “1.000” which remains a fixed three digit decimal number until you need more digits or you use divide