Texas Instruments TMC0594


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 TMC0501E 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 or a magnetic card reader. 

The TMC0594 MAGNETIC I/O chip provides the interface between the four-track magnetic card read/writer and the TMC0501E. 



Technical Specification

Item Min Typ Max Unit Comments
VSS   0   V  
VDD -10.5 -10.0 -9.5 V  
VGG -16.3 -15.8 -15.3 V  
PHI1, PHI2   225 230 kHz Opposite phases


The TMC0594 uses a standard DIP-22 package.

Pin Description

Pin IO Function Pin IO Function
1 O Write Track 2 22 O Write Track 3
2 I Read Track 2 21 I Read Track 3
3 O Write Track 1 20 O Write Track 4
4 I Read Track 1 19 I Read Track 4
5 V Common Voltage 18 V Motor Voltage
6 O Instruction words 17 V Common Voltage
7 I Calculating status 16 I External access
8 O Keyboard emulation 15 I Clock Input 2
9 O Motor on/off 14 I Clock Input 1
10 I Card position switch 13 V Negative Voltage VDD
11 I not connected 12 V Negative Voltage VGG

Comments: The purpose of the KR line to the TMC0501E is not clear. It seems to be used with the Card sense switches.

If you have additions to the above datasheet please email:

Joerg Woerner, February 02, 2001. No reprints without written permission.