Texas Instruments TI Programmable 59 TI-59

The TI-59 was an early programmable calculator, manufactured by Texas Instruments from 1977. It was the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM chip, capable of holding 5000 program steps). Just like the SR-52, it had a magnetic card reader for external storage. One quarter of the memory was stored on each side of one card. 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.