Digital Output (Do) Characteristics - IBM 1 Series Manual

Response Time
External Sync Deskew
Response time (<9 microseconds) is the time between the points at which
the user's input meets and maintains the required voltage for the logical 1
level and the 50% point of the resulting interrupt request in the PI mode.
This time includes an envelope of 5 microseconds in which the card could
be performing a Read PI or Read PI With Reset command.
The DI inputs must be stable for a minimum of 0.5 microsecond prior to
and after the activation of 'external sync.' Changes during this time result
in unpredictable data in the DI register.
Digital Output (DO) Characteristics
5-8 GA34-0033
Each digital output point is a nonisolated, solid-state current-sink point, as
represented by the equivalent circuit shown in Figure 5-5. When operated
without a user-source voltage, each point generates TTL-compatible
voltage levels. When operated with a user source higher than +5 volts,
each point operates as an open collector, solid-state current sink. Each
point is capable of sinking 100 mA in the "'on"' state. There is no
restriction on the number of DO points sinking maximum current
simultaneously.
+5 V
750 2 (resistance shown is nominalvalue)
User's connection
Figure 5-5. DO equivalent circuit