Prinztronic Mini type II

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Calculators: Handheld: Prinztronic Mini (type II)

		Size (approx):	55mm x 120mm x 12mm (max) (w,h,d) Weight 64g excluding batteries
		Power:	6.0V DC, 4 x AAA size batteries. Does not accept an adaptor. There is a battery save feature which powers down the display after 15 seconds of no use.
		Case:	Two-piece light and dark blue smooth plastic case with light blue keyboard surround. Square, compact and slim but slightly squeaky design. It has an oversized red display filter that gives a reasonably bright display. The filter has white printed text with the brand and model number. Buttons are clear see though with a positive click. As the buttons float lose the whole thing rattles like a box of matches. A true pocket calculator.
		Display:	8 digit red bubble-lens LED with a ninth digit for negative, display power save and error indicators
		Features:	Four functions, with percentages and display recover function
		Age:	1974
		Manufacturer:	Prinztronic, made in Hong Kong. Serial No. 269277 on battery compartment cover
		Comments:	One of the first striped down calculators achieving the price for the masses (£9.99) in the UK. Familiar design used for a number of variants. Original case is square shaped soft black plastic with flip over top. It tucks into a front pocket that cannot hold a manual. Whilst basic the logic is quite sound with good recovery and only let down by the pseudo fixed decimal bug.

Components:	1 x cpu: Texas Instruments TMS0803NC 7445 (week code 45 of 1974) 28 pin DIL, 0.6" width 1 x IC (Display driver): National Semiconductor NS445 DS/DM8864N 22 pin DIL, 0.3" width 3 x 3 digit bubble lens red LED modules 0 x transistor 0 x diodes 1 x capacitors 0 x resistor arrays 2 x resistors 1 x transformer unit 7452
Boards:	The main cpu board (026a) is placed front to front with the keyboard and stabilized with some tape. They are connected via a soldered 119-way block connector.
Construction:	Gently push and twist a lever on the right hand side looking from the rear. Inside the battery compartment you will just see a fixing lug. About 2cm from the top and the bottom there are others on this side. By the time these two are popped you can do the top and bottom lugs and finally the three on the other side. Very difficult - do not try if you do not want to damage your calculator.

Logic comments:	(C) is used once to cancel the last number entered and pressed again to clear the whole calculator.
	There is automatic constant on all four functions
	Input overflow is suppressed, inputting a ninth digit is ignored
	Negative numbers are shown with a "-" in the immediate left hand digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers
	Overflow shows the result and "C" ( or "E" if negative) in the far left (ninth) digit and is recoverable using (C)
	Divide by zero shows zero and "C" in the far left (ninth) digit and is recoverable using (C)
	It suffers from the pseudo fixed decimal bug: key in (1)(+)(0)(.)(0)(0)(0)(=) to give “1.000” which stays as a fixed three decimal point number until more digits are needed or divide or multiply is used.
	After 15 seconds the display switches off to save power. The minus sign in the far left (ninth) digit reminds you it is still on. Pressing (D) will recover the display.