Enterprex Model-Z50

		Home New Stuff Author Links Guest book Web-log	Adverts Bric-a-brac Calculators Components Ephemera Events	For Sale Glossary History Hit or Miss Radios Transport	Ultra Valves Wanted Metal Puzzles Caravan

Calculators: Handheld: Enterprex Model-Z50

		Size (approx):	72mm x 133mm x 21mm (max) (w,h,d) Weight 80g excluding batteries
		Power:	9V DC, 1 x PP3 size battery. It accepts an adapter (9V centre positive, 0.35W) through a socket on the right side in line with the (C) key.
		Case:	Roughly wedge shaped case in black matt and (originally) white glossy plastic. The brand and model, along with some graphics are printed in black text on the top section. A convex red plastic display filter gives a clean bright image. They keyboard surround is a flush brushed aluminium panel with additional lettering in black. They keys are medium travel with a plastic sounding click. This example is badly UV light-yellowed.
		Display:	8 digit red LED with individual bubble lens but no ninth digit
		Features:	Standard four functions with percentages and two function memory
		Age:	1977
		Manufacturer:	Made in Taiwan, serial number 50321
		Comments:	Basic calculator in a slim case that is the same as the Plustron Educational 1. The keyboard tends to look a bit empty with a missing row of keys. The original case is soft black plastic, open top with half-moon cut-outs either side. The logic is average being let down by the pseudo fixed decimal bug and seven digit negative numbers.

Components:	1 x cpu: Rockwell B5000C 7722 (date code of week 22 of 1977), 42 pin staggered DIL, 0.6" width black plastic with black cap 1 x 8 digit LED unit with individual bubble lens: Sharp DA6B 0 x transistors 0 x diodes 1 x capacitors 2 x resistors
Boards:	The keyboard assembly (70412 sticker) (85000 GICO JAPAN ZENY 31M GK342-B) sits lose on top of the cpu board (SH) and is connected by 11 short strong copper wires. The main board is held in place to the rear with some plastic guides. The single capacitor sits in its own cut-out on the main board to minimize the overall width.
Construction:	Difficult to open as it is held together by internal plastic lugs only. Damage is likely so if in doubt, do not attempt. The easiest way I found was to pop the top lugs first by pressing in the black rear section - but watch out as the top area is very thin. The front will eventually lift off.

Logic comments:	The (C/CE) key is used to clear the last entry whilst a second pres completely clears the calculator
	Input overflow is suppressed, keying in a ninth digit is ignored
	Negative numbers are represented by a "-" in the immediate left hand digit but as there is no ninth digit to travel into you are limited to seven digit negative numbers. This sign will replace the leading zero in numbers smaller than one: i.e. -0.5 is shown as "-.5"
	There is automatic constant on all four functions
	Overflow shows the result and all decimal points alight and is recoverable using (C/CE)
	Divide by zero shows "0.0.0.0.0.0.0." and is recoverable using (C/CE)
	There is no indication of memory store - you have to remember it
	Memory use is basic, (M) to store a number, (RM) to recall memory, so you need to key (C/CE)(M) to clear it
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to get "1.000" which remains a fixed three decimal digit number until you need more digits or use multiply or divide.