Texet L-0831

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Calculators: Handheld: Texet L-0831 (type I)

		Size (approx):	68mm x 125mm x 17-22mm (w,h,d) Weight 72g excluding batteries
		Power:	9.0V DC, 1 x PP3 size battery. Accepts an adapter (undefined) through a socket on the top side to the far right. A warning on the back states that the battery must be removed before using and adapter.
		Case:	The main case is made from two pieces of smooth black plastic with a prominent raised upper area to accommodate the battery. An oversized red plastic display filter sits flush, is heavily angled and gives a reasonably bright display with limited angle of view. This filter has raised lettering which is painted silver – and not survived very well on this example. The keyboard surround has white printed text for the key and switch labels. The small keys are short travel with a positive click which rattles when shaken.
		Display:	8 digit red LED with individual bubble lens with a ninth digit for negative and memory indication
		Features:	Basic four function with percentages and four-function memory
		Age:	1976
		Manufacturer:	No manufacturer details, made in Singapore, serial number 198656 - I think
		Comments:	Cheap and cheerful calculator that is quite attractive due to the shaped large display filter. The logic is sound with good recovery but let down by a poor memory overflow and pseudo fixed decimal bug. This calculator is very similar to the Adman L-0831T but without the aluminium panels. I suspect either Texet made this model for Adman - or they both used the same OEM in Singapore.

Components:	1 x cpu: Texas ZA0571 KES 7610 (date code week 10 of 1976) 28 pin DIL, 0.6" width 1 x 9 digit bubble lens LED; HP 1135-0243 0 x transistors 1 x diode 0 x capacitors 4 x resistors
Boards:	The single cpu board (AW145218 Rev C) sits above the keyboard assembly.
Construction:	Difficult this one - be careful! Gently prize the back of with a blunt (wooden) instrument whilst squeezing the front in. Start with the lower edge. The back will pop off. It is very easy to damage so if in doubt - don't do it.

Logic comments:	The (CE) key is used to clear the last number entered and the (C) key clears the whole calculator
	Overflow on the input of a number is suppressed, keying in a ninth digit is ignored
	There is automatic constant on all four functions
	The negative number is shown by a “-“ sign to the immediate left of a number travelling into the ninth thereby allowing full eight digit negative numbers
	An overflow shows the result flashing and is recoverable using (CE)
	A divide by zero results in zero flashing and is recoverable using (CE)
	Memory store is indicated by an upper "^r" in the far left (ninth) digit
	An overflow in memory will generate an overflow which is not recoverable - and you lose the memory contents
	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.

	Compare this with the Adman L-0831T inside case shot. Resize the new window for best comparison - please close this new window after use.
The image above shows the calculator with the rear of the case removed. Only a few extra components: a diode across the power supply to stop you plugging in the wrong polarity adapter, and four resistors. The board is attached to the front by melted plastic posts - about as cheap as you can make it - typical of this date. The diode in this example has been replaced, or is a late add-on and generally the soldering quality is not that good.	The box to the right measures 68mm by 128mm and is 23mm deep - so is just big enough for the calculator. It is a double tuck-end box printed pink and silver.