DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments TI-55
| Date of introduction: | 1977 | Display technology: | LED-stick |
| New price: | Display size: | 8 + 2 | |
| Size: | 5.8" x 3.1" x
1.4" 148 x 78 x 36 mm3 |
||
| Weight: | 6.4 ounces, 180 grams | Serial No: | 67030853 |
| Batteries: | BP7 | Date of manufacture: | wk 19 year 1980 |
| AC-Adapter: | AC9132 | Origin of manufacture: | USA (ATA) |
| Precision: | 11 | Integrated circuits: | TMC1503 |
| Logic: | AOS - 4 Pending Operations, 9 () | ||
| Memories: | 10 | ||
| Program steps: | 32 | Courtesy of: | Joerg Woerner |
| Download leaflet: | 
(US: 2.0M Bytes) |
Download manual: |
(US: 10.8M Bytes) |
The
TI-55 continued the line of scientific calculators with statistical capabilities
started with the SR-51 and continued with the SR-51A
and SR-51-II. In Europe the same calculator was
marketed as TI-51-III, mathematically and
historically correct.
The TI-55 was introduced shortly after [or before - continue here]
its sibling MBA
with advanced financial and statistical capabilities.
From a technical aspect the TI-55 continued the ideas of the SR-40
with three main differences: The LED-stick
using LED chips mounted and bonded to the printed circuit board (PCB), was expanded to 12-digits instead of
the 9-digits. The [ON] and [OFF] keys were replaced by a tw0-position sliding
switch and the battery
connector was changed from a 9V battery style to a small 3-pin header. As a
consequence the usage of disposable 9V batteries wasn't possible.
If we investigate into the origin of the main components used in the featured TI-55, we discover:
| • The LED chips were furnished by the SC Group in Dallas. • The lens provided by an Ohio based supplier. • The circuit board and the Integrate Circuit are from TI Singapore. • The board assembly was performed by TI Taiwan. • The keyboard was manufcatured at TI Lubbock, TX and final assembly took place in the Abilene, TX plant. |
The TI-55 added 4 keys to do some kind of programming. A small memory hold up to 32 key-codes to repeat simple calculations with different entry values. In comparison to the TI-57 the capabilities were disappointing.
If you are interested in the calculating accuracy of scientific calculators don't miss the Calculator forensics.
Simply by comparing the designation of the integrated circuits of the advanced line "Majestic" calculators, you'll get the all members of this family:
| • TMC1501
TI-57 • TMC1502 MBA • TMC1503 TI-55 |
From the TI-55 two different versions were reported, one with and without chrome-border around the display. Compare with the chromeless TI-55.
Don't miss the later TI-55 II sporting a stylish slanted housing and the modern LC-display.
Recently we
received from a fellow engineer of a Dallas based company a box with some
calculator prototypes. One of the surprises was a very early TI-55. The internal
construction of the calculator was already final, the only missing item was the date
code on the calculator chip. The housing itself carried with the magic
LTA 2577 number some confusing information. We assume that the TI-55 was
introduced after the MBA released in August 1977. Two explanations:
| • The TI-55 was released together with the TI-57 in May or
latest June 1977. • The TI-55 prototype uses a housing of the TI-57 and carries a wrong date code. |
| TI-55
An advanced slide rule calculator with statistical functions and simple programmability. Science. Engineering. Statistics. Social Science. Whatever your field. © Texas Instruments, 1981 |
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.