RFT minirex 75

Date of introduction:   Display technology:  LED-modules
New price:   Display size:  8
Size:  5.5" x 3.2" x 1.3"    
Weight:  11 ounces Serial No:  017790
Batteries:  4*NiCd  Date of manufacture:  year 1975
AC-Adapter:   Origin of manufacture:  GDR
Precision:  8 Integrated circuits:  TMS0105
Program steps:   Courtesy of:  Joerg Woerner

The minirex 75 manufactured in the GDR (German Democratic Republic) end of the year 1975 looks similar to other calculators based on TI's calculator chips. Compare it e.g. with the famous Bowmar 901B. The minirex 75 seems to be the successor of the minirex 74.

rft75_2.jpg (31657 Byte)The minirex 75 uses a charging craddle as a comfortable stand during operation and to charge the four internal NiCd-batteries.

RFT75_PCB.jpg (101040 Byte)From the technical point the inside of the minirex 75 is from higher interest than the awful appearance. The TMS0105 calculator chip seems to be the one and only western component. The round NiCd-cells look very unfamiliar, the display driver chips are GDR copies of the western SN75491 and SN75492. Even the transistors, resistors and capacitors look different from US products.

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