Справочник Пользователя для National Instruments PC-DIO-24

This section lists the timing specifications for handshaking with the PC-DIO-24.  The
handshaking lines STB* and IBF synchronize input transfers.  The handshaking lines OBF* and
ACK* synchronize output transfers.

The following signals are used in the timing diagrams on the subsequent pages.

STB*

Input

Strobe Input—A low signal on this handshaking line loads data into the input
latch.

IBF

Output

Input Buffer Full—A high signal on this handshaking line indicates that data
has been loaded into the input latch.  This is an input acknowledge signal.

ACK*

Input

Acknowledge Input—A low signal on this handshaking line indicates that
the data written from the selected port has been accepted.  This signal is a
response from the external device that it has received the data from the
PC-DIO-24.

OBF*

Output

Output Buffer Full—A low signal on this handshaking line indicates that
data has been written from the selected port.

INTR

Output

Interrupt Request—This signal becomes high when the 82C55A is
requesting service during a data transfer.  The appropriate interrupt enable
bits must be set to generate this signal.

RD*

Internal

Read Signal—This signal is the read signal generated from the control lines
of the PC.

WR*

Internal

Write Signal—This signal is the write signal generated from the control lines
of the PC.

DATA

Bidirectional

Data Lines at the Selected Port—This signal indicates when the data on the
data lines at a selected port is or should be available.