Texas Instruments SR Electronic Slide Rule Series.  Left to right:
1. SR-10: Two versions of this calculator exist; the other one has "SR-10" up near the LED display.
2. SR-11: This was the first TI scientific with small keys.
3. SR-16

1. SR-16-II: This one is noteworthy as the last TI scientific calculator without trig functions.
2. SR-50: The unusual styling makes this calculator a collectors' favorite.
3. SR-50A

Left to right:
1. SR-40: Later in time, though earlier in numerical sequence.
3. SR-51A
4. SR-51-II
 

Texas Instruments TI-30 series.  Still being extended.
1. TI-30: Probably the best-selling calculator ever.
2. TI-30X: Displaying 69 factorial--which was for years the "ultimate" number on a hand-held calculator.

1. TI-30Xa Solar
2. TI-30X IIS: Latest in the series--the "S" stands for Solar-powered.  A companion, the TI-30X IIB, is battery-powered.

1. TI-31
2. TI-33: LED model manufactured and sold in Europe.

Two more TI-Euro calculators:
1. TI-45: European version of the SR-40 (above), with a blue-green LED display.
2. TI-51-III: European equivalent of the TI-55 with 32 program steps available.

1. TI-34: This calculator has been produced in four different case style, three of which are in my collection.  This is the fourth in the series.
2. TI-54

TI Collegiate or SC-10: Notebook format.  30 of the right-side keys (the bottom 6 rows) can be redefined with the switch in the upper right.

TI-52: A scientific calculator in the horizontal format used by TI in the late 01980's.

1. TI-60X: This calculator is scientific, but not programmable.  It's similar to the TI-68--one curious difference is that the alphanumeric keyboard only includes twelve letters of the alphabet.
2. TI-68: This pinnacle of the TI scientific line is a somewhat-scarce collectible calculator.

PC-200 printer: This thermal printer is compatible with several TI calculators from the 01980's, including the BA-III and TI-66.