DATAMATH CALCULATOR MUSEUM |

Texas Instruments TI-55-II

Date of introduction: | 1981 | Display technology: | LCD |

New price: | $50.00 (SRP 1981) | Display size: | 8 + 2 |

Size: | 5.8" x 3.1" x 0.90" 147 x 79 x 23 mm ^{3} |
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Weight: | 3.7 ounces, 106 grams | Serial No: | 210035 |

Batteries: | 2*LR44 | Date of manufacture: | wk 37 year 1981 |

AC-Adapter: | Origin of manufacture: | USA | |

Precision: | 11 | Integrated circuits: | CD4555, CD4556 |

Memories: | 1-8 | ||

Program steps: | 56-0 | Courtesy of: | Joerg Woerner |

Download leaflet: | (US: 2.2 MByte) | Download manual: | (US-QR: 1.5 MByte) |

With the TI-55-II Texas Instruments added in 1981 a new calculator line to the existing slimline series. In you compare the slanted TI-55-II with a typical slimline calculator like the TI-53 you will notice some changes:

• Larger display gives 8+2 digits instead 5+2 • 45 keys instead of 40 keys • More space for the electronics |

The display was not in one line with the keys but slanted
towards the user. Together with a perfect contrast and large digits the
calculator looked very professional. In practice the keyboard of all members of
the slanted scientific/financial calculators was terrible, either bouncing or
without any contact. Most users of the TI-55-II remember: "The -II
designation was evidently for the number of keystrokes that were recorded with
one button press". The calculators were usually replaced for free by Texas
Instruments with TI-55 III's which did not inherit
the bad genes of their forefathers.

Some very early calculators of the second generation were sold
under the old designation TI-55 II with just a missing hyphen. View a very rare
TI-55 II
manufactured in Taiwan here.

The two-chip design of most slanted calculators allowed more features compared to the slimline series. The TI-55-II for example added a total of 8 memories to the basic functions. Find more information about the TP0456 calculator chips here. The TI-88 added a third microcontroller to this Master/Slave approach.

Known from the TI-53 and the original TI-55 is the simple programmability, here each memory could be converted to 7 program steps. A nice enhancement was a function to integrate with the Simpson-rule. If you are interested in the calculating accuracy of scientific calculators, don't miss the Calculator forensics.

One calculator in the TI-55-II series - the TI-54 - could manage arithmetics with complex numbers. Once again a "first" from Texas Instruments.

Don't miss an early prototype of the TI-55-II.

In Brazil the housing of the TI-55-II was changed to accommodate two AA-sized batteries instead the small coin shaped LR44 type. View this rare beauty here.

The US based company Jeppesen Sanderson developed a very
interesting navigation computer called prostar based on
the TI-55-II.

TI-55-II
With 112 powerful functions for professional engineering, science, and math applications. Easy keyboard programmability; including function evaluation and integration features, saves time on repetitive problems. Also the most needed statistical functions for better data analysis. Use up to 8 memories. Built-in conversion functions for fast transition between various measurement systems. Plus: roots, powers, reciprocals, log, trig and hyperbolic functions. Enter data in standard, scientific, or engineering formats. © 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.