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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


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.


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.