Dive into an IBM Single Shot (SS) gate from an IBM 1130 SLT card

SINGLE SHOT GATE PURPOSE

These gates produce a single pulse of a given duration when triggered, thus converting some logic condition into a pulse that will in turn trigger some other gates. In practice these are edge triggered, the method called AC Trigger by IBM. When the input has a trailing edge, at the same time that the gate input is low, this gate produces a negative going pulse of a fixed duration. 

IBM SCHEMATIC OF AN SS GATE

Single Shot circuit from IBM 1130

The left side consists of the edge triggered input. On the actual card, the resistor is tied to ground thus always enabling this to emit pulses on the falling edge of the input signal. The resistors and inductor determine the fixed pulse time for this monostable circuit. It flips the output transistor on, driving the output low, then when the target time elapses the circuit resets, turning off the transistor.

COMPONENT PARTS IN THE SS GATE

The SS gate is implemented with:

• half of an SS can
• half of a FDD can
• a 2391124 3.9uh coil
• a 2390301 resistor pack(3@ 150ohms, 1@ 1.8K)
• a 10ohm discrete resistor
• sharing a 2390477 resistor pack (2@1K per SS)
• a 2391304 capacitor (22pf)

The SS can is actually four separate transistors. Two of them are used for a single shot. The FDD is four separate dual-diodes, that is pairs of diodes tied together at one end. The single shot uses two of the pairs in the can. 

Thus we can see that a single shot uses four components and shares half of three more. A pair of single shots would use 11 components on the SLT board.