Texas Instruments TI-2550 III

Date of introduction:  1976 Display technology:  Fluorescent
New price:  $29.95, 24.95 Display size:  8
Size:  5.8" x 3.2" x 1.3"
 147 x 81 x 32 mm3
Weight:  6 ounces, 170 grams Serial No:  214528
Batteries:  BP3 Date of manufacture:  wk 40 year 1977
AC-Adapter:  AC9130A Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS1043
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner
    Download manual:   (US: 2.8M Bytes)

TI-2550-3_1.jpg (28983 Byte)The TI-2550 III replaced within few month the TI-2550 II which lacked the [+/-] key to change the sign of an entry. Unfortunately the [F/2] switch of the predecessor is now missing.

TI-2550-3_2.jpg (74401 Byte)The electronics of the calculator was cost optimized: The original TMS1071 was replaced with a cheaper TMS1043 and the new battery pack BP3 replaced the former BP2. With just one rechargeable AA-sized NiCd battery in combination with the power hungry electronics the operating time was really short. 
Please notice the TI-1265 using just few functions of the TMS1043 IC.

The other changes were minor, the layout of the keyboard was better organized.

In some European countries the rare TI-2550-IV continued and finished the TI-2550 line of calculators.

If you add the [pi] key to this calculator you get the Canon Palmtronic F-31 or Toshiba BC-8112SL. A more compact design was introduced with the Canon Palmtronic LD-8Ms.

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Joerg Woerner, December 5, 2001. No reprints without written permission.