Texas Instruments TI-58C Implant Power Calculation

Date of introduction:  1982 Display technology:  LED-stick
New price:   Display size:  10 (8 + 2)
Size:  6.4" x 3.2" x 1.5"
 162 x 81 x 37 mm3
Weight:  8.5 ounces, 240 grams Serial No:  8206713
Batteries:  BP1A Date of manufacture:  wk 46 year 1981
AC-Adapter:  AC9131 Origin of manufacture:  USA (ATA)
Precision:  13 Integrated circuits:  TMC0501E, TMC0580 (CD2400), TMC0580 (CD2401), TMC0573, TMC0591, Toshiba TC5047AP
 TMC0540 (CD5650)
Logic:  AOS - 8 Pending Operations, 9 ()    
Memories:  0-60    
Program steps:  480-0 Courtesy of:  Joerg Woerner

TI-58C-SRK_BACK.jpg (529409 Byte)Shortly after the TI-58 and TI-59 Programmable calculators were launched in May 1977, the first application specific solutions based on the Solid State Software Modules™ approach appeared on the market. Within just a few years a whole spectrum of different software modules were introduced: Payroll Computing, V/STOL Calculations, Pool Water Analysis, Screw Joint Calculations, Mud Hydraulics, Federal Income Taxes and dozens more.

The SRK™ module developed by Computational Technology, Inc., Illinois, was used to calculate the power of intraocular lenses. An intraocular lens (IOL) is an implant in the human eye to replace the existing crystalline lens, or to change the eye's optical power. Sanders, Retzlaff, and Kraff developed in 1980 a regression-based intraocular lens calculation formula, known as the SRK formula that is with some modifications still in use today.

Dismantling this Implant Power Calculation / SRK calculator reveals a standard TI-58C calculator manufactured in Autumn 1981 in Abilene, Texas. Please notice that the printed circuit board (PCB) of the calculator was assembled in Canada.

SRK™ is a registered trademark of Computational Technology, Inc.

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© Joerg Woerner, November 10, 2009. No reprints without written permission.