Search Poll
Enable,
Disable,
Adprep,
Prepare Sense Halt I/O Instruction
The Interface Stop causes the
command to cease transferring
data to the channel and stop
monitoring for valid addreRses. Unit Check status (CSW bit 38)
and Lost Data (sense-bit 6) are
set to one. Part of the received
data will always be lost when the
Interface Stop occurs.
The stop signal indicates that
the last character (EaT) has
been transferred from main
storage to the SF under the cur­
rent Poll command. The SF sends any buffered characters
and ends the command with
Channel End and Device End
status (CSW bits 36 and 37). The SF waits for the reply to the
poll operation before ending the
command. Note that the program
must ensure that the byte count
is exactly as large as the poll
list so that the last character
transferred by the Poll com­
mand is index character for the
last poll in the list.
No data-byte transfers occur
with execution of these commands;
accordingly, Interface Stop is
never signaled.
The Interface Stop signal causes
this command to end immediately
with Channel End and Device End
status (CSW bits 36 and 37).
A Halt I/O (HIO) instruction can be issued to the 2703 during the execution of a command. When HIO is
issued, various actions take place, depending on the
command being executed:
Command Set Mode HIO Action
If HIO is received before the Set Mode byte has been accepted
from main storage, the com­
mand ends immediately with
Channel End, Device End, and Unit Exception status (CSW bits
36, 37, and 39). The SF is
reset. If HIO is issued at other
Enable
Dial
Write
Read
Prepare
times, it has no effect on the Set Mode I s execution. On a switched network, if the HIO is received when the data
set is not operational (i. e. ,
before the call has been answer­
ed), the command is ended with
Channel End, Device End, and Unit Exception status (CSW bits
36, 37, and 39). Otherwise, HIO has no effect on the normal
execution of the Enable command
and the SF is not reset.
An HIO received before the
Interface Stop signal has been
transmitted to the SF (e. g., the
entire number has not been
dialed) results in aborting the
dialing operation, the resetting
of the enable and dial circuitry,
and the immediate ending of the
command with Channel End,
Device End, and Unit Exception
status (CSW bits 36, 37, and
39). If HIO is received after the
Interface Stop signal has been
received, the dialing operation
proceeds normally. HIO causes the SF to transmit
any currently buffered characters
and then terminate the com mand. HIO causes the command to
stop transferring data to the
channel. The Unit Check status (CSW bit 38) and Lost Data
(sense-bit 6) bits are set to one. Part of the data will always be
lost when the HIO is issued
during a Read command execu­
tion. The command ends im­
mediately.
If HIO is issued before character
phase is established, the com­
mand ends immediately with
Channel End, Device End, and Unit Exception status (CSW bits
36, 37, and 39). If HIO is
issued after character phase has
been established, there is no
effect.
63
Adprep
Search
64
If rno is issued before the group,
selection , or polling acc!ress is recognized, the ends immediately with r'hannel End, Device End, and unit Exception status (CSW bits 36,
37, and 39). Otherwise, the
operation is not affected. HIO causes the cessation of data
transfer to main storage. Unit Check status (CSW bit 38) and
Lost Data (sense-bit 6) are set
to one. The command ends
immediately. Part of the data
will be lost when the HIO is issued, Poll
Disable
Sense rno causes the command to end
immediately with Channel End
and Device End status (CSW bits
36 and 37). HIO should not be
used with the Poll command.
The HIO instruction has no effect
on the Disable command. HIO causes this command to
end immediately with Channel End and Device End status (CSW bits 36 and 37).
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