DATAMATH CALCULATOR MUSEUM
With the TMC05xx building blocks Texas Instruments created a novel architecture for scalable scientific calculators. The architecture uses minimum a 2 chip design with the Arithmetic chip TMC0501 and the SCOM (scanning read only memory) but was expandable to a maximum of 8 SCOM's, additional RAM as program memory for programmable calculators, additional RAM for general purpose registers and even a chip driving a printer. Most scientific and programmable calculators from Texas Instruments between the years 1974 and 1982 (SR-50..TI-59) use these chips.
The TMC0521 Scanning Read Only Memory SCOM contains 1k*13 instruction memory and 16*16 digits constants.
Additional functions of the TMC0521 include scanning of the display digit driver outputs and the keyboard.
Note: The early ROM-code TMC0521-2 and -4 is less accurate and was replaced July, 1974 with the -5 code. Please find the comparision in the Calculator forensics.
|PHI1, PHI2||225||230||kHz||Opposite phases|
The TMC0521 uses a
standard DIP-28 package.
|1||O||Digit driver 14||28||O||Digit driver 14|
|2||V||Negative Voltage VGG||27||O||Digit driver 13 (OVER)|
|3||V||Negative Voltage VDD||26||O||Digit driver 12 (E-MSD)|
|4||IO||SCOM Interface D0||25||O||Digit driver 11|
|5||IO||SCOM Interface D1||24||O||Digit driver 10|
|6||IO||SCOM Interface D2||23||O||Digit driver 9|
|7||IO||SCOM Interface D3||22||O||Digit driver 8|
|8||O||Instruction words||21||O||Digit driver 7|
|9||I||Calculating status||20||O||Digit driver 6|
|10||I||External access||19||O||Digit driver 5|
|11||I||Clock Input 2||18||O||Digit driver 4|
|12||I||Clock Input 1||17||O||Digit driver 3 (M-LSD)|
|13||V||Common Voltage||16||O||Digit driver 2 (E-MSD)|
|14||O||Digit driver 0||15||O||Digit driver 1 (E-LSD)|
The keyboards of all calculators based on the TMC0501 Arithmetic chip consist of a x/y-matrix connected to the SCOM digit driver outputs and the TMC0501 keymatrix inputs.
Comments: The R-D switch is detected with a diode between D14 - KT.
If you have additions to the above datasheet please email: firstname.lastname@example.org.
© Joerg Woerner, February 02, 2001. No reprints
without written permission.