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[[File:Tek21-31.jpg|right|300px|thumb|Tektronix 21 and 31 calculators]] | [[File:Tek21-31.jpg|right|300px|thumb|Tektronix 21 and 31 calculators]] | ||
The '''Tektronix 21''' and '''Tektronix 31''' are programmable desktop calculators. | The '''Tektronix 21''' and '''Tektronix 31''' are programmable desktop calculators. | ||
The | The y feature a complete set of transcendental functions. The 21 supports simple programs (sequences of keystrokes) whereas the 31 supports conditional branching and subroutines. | ||
Several interfaces were available: | Several interfaces were available: | ||
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* [http://classiccmp.org/dunfield/calc/h/tekm31.jpg Tek 31 picture] / [http://www.classiccmp.org/dunfield/calc/h/tekm31b.jpg back side] | * [http://classiccmp.org/dunfield/calc/h/tekm31.jpg Tek 31 picture] / [http://www.classiccmp.org/dunfield/calc/h/tekm31b.jpg back side] | ||
==Internals == | |||
The 21 and 31 are built around a custom LSI chip set, the 156-0243-00 Adder-Subtracter, 156-0238-00 Working Register Storage, 156-0239-00/156-0240-00/156-0242-00 Function Decoding, 156-0235-00 Microcode Routine Address ROM, 156-0231-00 through 156-0234-00 Microcode ROM/Next Address Latch, 156-0237-00 Timing and Constant Storage ROM, 156-0236-00 K Register Storage and 156-0241-00 A & C Operation Control ROM. These chips were manufactured by American Microsystems, Inc. as full custom parts. | |||
==Pictures == | |||
<gallery> | <gallery> | ||
Tek 31 1.jpg | Tek 31 1.jpg |