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.

The calculator could be powered from an external adapter or from its internal NiCd rechargeable battery pack.

[edit] Display

10-digit LED display

The red LED display showed 10 decimal digits of precision.

[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.

Programming example

Here is a sample program that computes the factorial of an integer number from 2 to 69. For 5!, you'll type 5 A and get the result, 120.

Op-code        Comment

LBL A          You'll call the program with the A key
STO 01         stores the value in register 1
1              starts with 1
LBL B          label for the loop
*              multiply
RCL 01         by n
DSZ 1 B        décrements n and back to B until n=0
=              end of loop, the machine has calculated 1*n*(n-1)*...2*1=n!
INV SBR        end of procedure

Here is the same program written for TI Compiler (see external links):

#reg  01 counter
#label A factorial

LBL factorial
  STO counter
  1
  FOR counter
    * @counter
  LOOP
  =
RTN

#end

[edit] Memory

In comparison to its contemporary main competitor, Hewlett-Packard's HP-67, the TI-59 had an extremely large memory of up to 960 user program steps or 100 memories (adjustable between the two, in steps). Contents of this memory were lost, when the calculator was turned off.

[edit] Magnetic card reader

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

Programs and data could be stored on small magnetic cards when the calculator was turned off and quickly reloaded when needed. Click

for a video of the card reader in action.

[edit] Solid State Software Library

The TI-59 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.

[edit] Printer

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

[edit] External links

• TI-59 homepage maintained by Dejan Ristanovic
• TI-59 library maintained by Viktor Toth
• TI-59 on MyCalcDB (database about 70's and 80's pocket calculators)
• TI-59 birthday Short article published on the TI-59's 30th birthday
• (French) Utilisateur TI, programmes en ligne, page de TI Compiler
• (English) TI User, programs on line, TI Compiler page.