IBM Series 1 User Manual page 187

device that is to respond to the current operation. Device
address is used during both an I/O active sequence or an
interrupt service active sequence. When the DPC adapter is
configured to attach less than 16 I/O devices, the leading
bites) of the device address are always zero(s}.
Dat~ Bu§ Ou1
Data bus out is an 18-bit outbound bus with 16 bits of data
and 2 parity bits, odd parity by byte. This bus is used to
transfer data and control information to the I/O devices and
is active during write Data or write control operations.
During the Write Data or write Control operation, data
bus out is active from 200 nanoseconds before the rise of
the I/O active tag until the fall of the select response
tag, measured at the output of the
DPe
adapter card. During
the inactive state, the data bus out is logically zero
including parity. When the parity option is not selected,
the device uses only the 16 data lines.
Interrupt service active is an outbound tag line used to
signal an I/O device that an interrupt service sequence now
may begin. The tag is active from 200 nanoseconds after the
device address is activated and remains active until the
fall of the select response tag, measured at the output of
the DPe adapter card.
strobe is an outbound line to the I/O device presently being
selected (device address equivalent to the preassigned
address of an I/O device) during an I/O active sequence or
an interrupt service active sequence.
During an I/O active sequence, the device should use
strobe to register data on the outbound data transfer or use
it to reset data (e.g. read with reset command) on the
inbound data transfer. During an interrupt service active
sequence, the selected device uses strobe to reset its
interrupt request, interrupt information byte (lIB), or
interrupt status byte (IS8).
If a parity error is detected by the processor I/O
channel during a Read Data or Read operation, strobe is
inactive throughout the sequence.
If the DPC adapter card
parity option and a parity error
Data or write Control operation,
throughout the sequence except
Device Reset command.
6-6 GA34-0033
is configured without the
is detected during a write
the strobe line is inactive
during the system-defined