TI-59

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A TI-59 showing one card in the holder on the front of the calculator and another being inserted into the card reader in the side.

The TI-59 was an early programmable calculator, manufactured by Texas Instruments from 1977. It was one of the first LED calculators with the capability and flexibility to take on many real-world calculation challenges, and quickly became popular with professionals in many fields.

It was the first calculator to utilize removable ROM program modules. The Master Library Module ROM was included with the TI-59, and contained several useful pre-programmed routines and even a game. Additional modules - for such applications as real estate, investment, statistics, surveying and aviation - were sold separately.

The TI-59 had an extremely large memory of up to 960 user program steps or 100 memories (adjustable between the two, in steps). The LED display showed 10 digits of precision.

The Master Library Module shown removed from its socket in the back of the calculator. Magnetic card storage folio also shown.

The calculator could be powered from an external adapter or from its internal NiCd rechargeable battery pack - at a time when a rechargeable power pack was a technological innovation. Programs could be stored on small magnetic cards when the calculator was turned off and quickly reloaded when needed.

Also available for the TI-59 was a thermal printer (the PC100C); the calculator was mounted on top of the printer.

[edit] Programming

Programming simple problems with the TI-59 was a very straightforward process. In programming mode, the TI-59 simply recorded key presses. Alphabetical keys provided easy access to up to ten entry points.

However, exploiting the computerlike capabilities of the TI-59 was a different matter. Although the TI-59 was Turing-complete, supporting straight-line programming, conditions, loops, and indirect access to memory registers, and although it supported limited alphanumeric output on the printer only, writing sophisticated routines was essentially a matter of planning machine language and using a coding pad.

A large degree of sharing occurred in the TI-59 and TI-58 C community.