Nestler T52

		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: Nestler T52

		Size (approx):	80mm x 134mm x 19mm (max) (w,h,d) Weight 104g excluding batteries
		Power:	3V DC, 2 x AA size batteries. It accepts an adapter (3V DC, 0.3W, centre positive) through a socket on the top side to the far right.
		Case:	Two piece dark brown gloss plastic slim case. The top area holds a black printed metallic sticker with the brand name and model number in its own recess. Below this is a strip of mottled plastic, which then leads to an oversized flat and flush green plastic display filter. The keyboard surround is brushed aluminium panel with black text for the on/off switch label. They keys are medium travel, soft touch with a faint click.
		Display:	8 digit green VFD with a ninth digit for negative, error and memory indication
		Features:	4 function calculator with percentages, square root and four function memory
		Age:	1977
		Manufacturer:	No details, German text on back label, serial number 201330
		Comments:	Solid feeling calculator from this German marketing brand. The logic is quite sound with good recovery and only let down by negative square roots. Similar inside to the very slightly earlier Nestler OH1002A.

Components:	1 x cpu: Texas TMS1045NL 7749 (week 49 of 1977), 28 pin DIL, 0.3" width black plastic 1 x 9 digit VFD unit: single tube flat face: itron FG95D6 KBA 1 x transistor 5 x diodes 5 x capacitors 5 x resistors 1 x transformer: 580
Boards:	The keyboard assembly sits above the main cpu board (93-622A) and the whole assembly sits lose guided by some plastic pillars. The two are joined together by a 15-way ribbon cable.
Construction:	Difficult top open as it is held together by internal lugs and the plastic sides are quite stiff. There is a coin slot on the upper edge, which does not help much. Lever this edge apart with a blunt object, pushing inwards the rear section then travel down one of the sides. Eventually the front will lift off. Damage is highly likely, so I wouldn't bother.

Logic comments:	The (C/CE) button is used once to clear the last entry of a number and a second time to clear the whole calculator
	Overflow on number input is suppressed – keying in a ninth digit is ignored
	There is automatic constant on all functions
	Negative numbers are shown by a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers
	An overflow shows the result and “C” (or “E” if negative) in the far left (ninth) digit and is recoverable using (C/CE)
	Divide by zero shows zero and C” in the far left (ninth) digit and is recoverable using (C/CE)
	Memory store is indicated by an upper “ⁿ” in the far left (ninth) digit
	Overflow in memory stores the result divided by 10⁸
	Negative square roots are allowed and result in a negative number
	No major bugs found