Texas Instruments TI-1200

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Calculators: Handheld: Texas Instruments TI-1200

		Size (approx):	70mm (max) x 138mm x 35mm (max) (w,h,d) Weight 110g excluding batteries
		Power:	9V DC, 1 x PP3 size battery. Also accepts adaptor (undefined). Socket at top side in the middle.
		Case:	Typical Texas bulging shape this calculator tilts towards you at around 15 degrees. Dark brown two-piece mottled plastic case with smooth metal keyboard surround in cream. Key ID is black painted surrounded by gold boxes and topped of with a large orange surrounding. The functions are highlighted using a caramel colour. Model number is painted. There is gold painted rim to the flat and flush red plastic display filter. The brand name is on a metal painted plate stuck under the display. A basic calculation guide is attached to the back and the on/off switch is on the left side, just above midway.
		Display:	8 digit red LED with bubble lens (ninth right-most used for minus flag)
		Features:	4 function calculator with percentages
		Age:	1975
		Manufacturer:	Texas Instruments, made in Italy. Serial number missing on this one.
		Comments:	Well built calculator with keys that give a positive click. LED display has a good angle of view. Apparently you can remove the keyboard plate to reveal the unused keys; a change sign and four memory key, which are used on the sister calculators like the TI-1250. Available from 1975 to 1977 this is an early model.

Components:	1 x cpu: Texas Instruments TMS0952 NC, 7527 (date code week 27 of 1975) 28 pin 0.6" DIL black plastic 1 x 9 digit LED display unit with bubble lens 1 x capacitor 4 x resistors
Boards:	The keyboard assembly sits on top of the main board and is held in place by two melted lugs. It is joined to the main board via 8 long wires. A small board (UNI 9 DIG C 015512 7523F) holds the display unit and is held in place by stiff connecting wires.
Construction:	Remove the four screws from the back, and the front lifts off easily.

Logic comments:	The (CE) button is used to clear last entry of a number and the (C) to clear the whole calculator.
	Overflow on number input is suppressed, typing in a nine digit number ignores the ninth digit
	An overflow error is flagged a flashing answer with the decimal point on the first digit. Number is recoverable with (CE)
	Divide by zero results in a flashing "0."
	There is automatic constant on all functions
	Negative numbers are flagged by a "-" sign in the immediate left digit, travelling into the ninth on 8 digit numbers.