Prinztronic SC1001M

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Calculators: Handheld: Prinztronic SC1001M

		Size (approx):	68mm x 130mm x 23mm (max) (w x h x d) Weight 94g not including batteries.
		Power:	3.0V DC using 2 x AA size batteries. It accepts an adapter through a socket on the left hand side just above the display. The on/off switch is on the right hand side near the top.
		Case:	Compact model made from a two-piece blue matt plastic case. A blue and silver metallic sticker is printed with the brand and model number and sits in its own recess above the display. The convex (magnifying) green display filter is slightly tilted and gives a clean image of the rather thin digits. They keyboard surround is a matching blue plastic printed with white and yellow text. The keys are short travel, loud click type, which have not survived well in my example. They are quite loose so the whole thing rattles like a box of matches.
		.Display:	8 digit green VFD with a ninth digit for negative, memory, function and error indicators.
		Features:	Standard four functions with reciprocal, pi, square root, logs, trigs and five-function memory. 5+2 scientific display mode. The display is left leading rather than the common right reading of today’s calculators.
		Age:	1976
		Manufacturer:	No manufacturing details except made in Hong Kong. I cannot find a serial number but my example has a poor back sticker.
		Comments:	Unusual calculator that has a colour theme mess. If they had used a blue display filter and dropped the yellow labels it would have been great. The logic appears OK but the lack of recovery and limited scientific mode digits let it down. Very cheaply made calculator like the Radofin 1660 with a case shape familiar from other models.

Components:	1 x cpu: {square spiral logo} CF596 7603 (3rd week of 1976), 28 pin DIL, 0.6" width black plastic 1 x 9 digit VFD; single tube flat face 3 x transistors 4 x diodes 4 x capacitor 20 x resistors 1 x transformer
Boards:	The main cpu board (Radofin XM-551-20-B) is held over the keyboard assembly by two plastic lugs. There are very unreliable solder-jointed stiff connecting wires to the keyboard assembly which is fixed to the front also by plastic lugs. Looks very cheap.
Construction:	One of those difficult ones that is held together with nothing but lugs - if in doubt do not try as damage may result. The easiest way I found was to pop the right hand side lugs by levering out the back section.

Logic comments:	The (C/CE) key is used to once cancel an entry whilst a second press clears the whole calculator
	Input overflow is suppressed inputting an ninth digit is ignored
	Negative numbers are shown with a "-” in the far left (ninth) digit, thereby allowing full eight digit negative numbers.
	There is automatic constant on all four functions
	Divide by zero just shows “E0.” Starting in the far left (ninth) digit and is not recoverable
	Overflow just shows “E0.” starting in the far left (ninth) digit and is not recoverable
	There is indication of memory store by the bottom right vertical segment of the far left (ninth) digit.
	The higher functions are accessed by a two key system; i.e. for square root of 6-key in (6)(F)(1). An “”F” is displayed in the far left (ninth) digit to remind you of function mode.
	Negative square roots are not allowed and show “E0.” starting in the far left (ninth) digit and is not recoverable
	The scientific display mode is accessed by (F)(EEX) or automatically if the number gets bigger than eight digits. It can display a five-digit mantissa and two-digit exponent. (CN) change notation can get you back to scientific mode after (EEX).
	The memory exchange function (MEX) swaps the current display for the memory content