TI SR-50

Most notable among the added functions were the ability to enter x:y pairs and do linear regression analysis on them.

The later and lighter versions SR-50A and SR-51II and SR-51III were based on smaller ICs and battery packs and reached broadest distribution.

It was thicker and longer and could perform 224 program steps recorded on magnetic cards, similar to its competitor HP-65.

The matte white upper face of the cards could be marked with pen or pencil to indicate the program and the functions assigned to the calculator's programmable keys.

[clarification needed] The card could be stored in a slot above the programmable keys with its markings visible.

In 1976 Texas Instruments released the TI-30 budget calculator at one-third the price of the SR-50, so sales of the SR-50 quickly dropped.