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Texas Instruments PM550-301 Programmer

Date of introduction:  1974 Display technology:  VFD
New price:   Display size:  20 alphanumeric
Size:  10.7" x 10.0" x 3.7"    
Weight:  3 pounds 7 ounces Serial No:  911052
Batteries:    Date of manufacture:  
AC-Adapter:  120V AC Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS8080
Memories:      
Program steps:   Courtesy of:  Joerg Woerner

This page starts with a simple question: What is a PLC or Programmable Logic Controller ? The answer: A device used to automate monitoring and control of industrial plant. You could think about a computer without a keyboard or display unit running the same program day and night using sensors and actors like switches and relay's. An example could be found in the crossing lights in your town. 

During program changes or maintenance schedules the operator uses a socalled Programmer to communicate with the PLC. Texas Instruments is together with companies like Rockwell Automation and Omron one of the big players in the PLC market. About 1974 they introduced this huge PM550-301 Programmer.

The inside view of the Programmer gives you a complete 8-bit computer system based on the TMS8080 8-bit processor. The original design of this microprocessor was designed by Intel, remember the line I4004, I8008, I8080, I8085 and I8086.

You feel familiar with the housing of this PM550-301 Programmer ? Compare it with the TI-450.


If you have additions to the above article please email: joerg@datamath.org.

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