Wednesday, April 27, 2022

My plan for the next day or two will focus on validating that switches are working, not oxidized

 STATE LOGIC FOR THE 1130 DEPENDS ON SWITCHES ON CONSOLE

In some cases, both a positive and a negative signal must be generated when a switch is depressed. IBM accomplishes this with a DPDT switch whose poles produce the two opposing states. If one of them is not working correctly, as when a contact is oxidized so much it doesn't conduct, then the state machine can be very confused. 

I will therefore go through with a continuity meter, deoxidizing spray and burnishing tool to make sure that all the contacts are working properly. I will do this in four areas - the console display pedestal with its Mode rotary switch, the pushbuttons on next to the keyboard, the CE switches inside the top cover, and the console entry switches in front of the console typewriter.

Once that is done I can begin to hook up scopes and other tools to debug the state of the machine starting with the clocks and working outward. 

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