8x300 design guide - Al Kossow's Bitsavers - Trailing-Edge

2.5.2 Interrupt Control (Handshake)
The timing of the handshake procedure is shown in Figure 2-33. The
time between the activation of the INTERRUPT signal and the
leading edge of -INTERRUPT ACKNOWLEDGE (time A) is T cycle +
10 nanoseconds minimum, and 3 x tc cle + 60 nanoseconds
maximum, (when Execute has to be taken inro account).
The time between the de-activation of the INTERRUPT signal and
the trailing edge of INTERRUPT ACKNOWLEDGE (time B) is 10
nanoseconds mimimum, and 3/4 x tcycle + 50 nanoseconds
maximum.
INTERRUPT SIGNAL
INTERRUPT ACKNOWLEDGE
Figure 2-33. Handshake Timing
The INTERRUPT signal must remain active until the INTERUPT
ACKNOWLEDGE goes high. The INTERRUPT ACKNOWLEDGE is
de-activated when the INTERRUPT signal is no longer active.
\Nhen an INTERRUPT signal occurs with no INTERRUPT INHIBIT
present, the signal is synchronized in flip-flops SYNC 1 and SYNC2
because the output of SYNC1 may be a very small pulse if the
INTERRUPT signal occurs very near the leading edge of MCLK. If
there is an EXECUTE instruction, the setting of SYNC2 is inhibited
for one cycle. When SYNC2 is set, the signals PROM DISABLE,
RETURN ADDRESS CLOCK and INTERRUPT VECTOR ENABLE
become active. The acknowledge flip-flop (ACKN) is also set.
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