Testing the 1130 MRAM core memory replacement on the IBM 1130 system - part 1

IT IS TIME TO HOOK THIS INTO THE 1130 AND TEST THERE

The three ribbon cables T1, T3 and T4 were disconnected from the gate B, compartment C1 backplane which houses the original core memory. These were inserted onto the connectors on my PCB. 

The red and black wires were connected onto the terminal strip TB2 just below gate B compartment C1 to provide the +12V power for my board. 

With that done, it was be time to power up the 1130 and check out the new memory.

TESTING ACCESS TO SOME WORDS USING THE LOAD FUNCTION

The IBM 1130 rotary mode control has a LOAD position, which uses the 16 console entry switches (CES) to input data and address values. I first set up an address on the CES then push the Load IAR button. This sets the memory address (SAR) to the chosen location. I change the CES to the data value I want to write into the chosen memory location and push the Start button on the console. This stores the value into the chosen memory location.

I put values into unique addresses using this method, then turn the rotary mode control to DISPLAY. In this mode, it reads the data in memory rather than writing it. First set up the chosen address on the CES and push Load IAR to select it. Next push the Start button to see the contents of that location display on the Storage Buffer Register (SBR) line of lights on the console.

RESULTS OF FIRST TESTS

When I attempted a DISPLAY the results were all zeroes with bad parity. I pulled out the oscilloscope to watch signals to see what is occurring. The line that I expected to see the +Storage Read signal appear was not changing. 

I will go home, review all the ALDs I have to ensure that I picked correct pins on the cables, then track down the exact issues tomorrow. I did verify that there were good voltages - +12V from the 1130 and +3.3V from the voltage regulator module - thus my board should be interacting.