Model 10AST "A" Slot Test Card
is a special diagnostic and service tool. Plugging into the Slot Connector of any mainframe "A Slot," its front section protrudes from the slot. Through an array of labeled terminal posts, it thus allows voltmeter or oscilloscope observation of power and reference voltages, logic and calibration signals, data-bus lines, and all other signals pertinent to the slot in question.
The 10AST also lets the system read and display the slot's Signal Common, Power Common, DC Reference, Input Signals, and ±9 VDC Power Supply levels, as it would any standard System 10 data channels.