/' Main
Storage S/360 CPU Master Station "- Synchronous
Feature 2703 Main Storage SSF SSF = Station Selection Feature Required
Figure 14. Multipoint -' Synchronous
Feature 2703 S/360 CPU SSF Tributary Stations Multi -point
Network
Synchronous
Feature
2703 S/360 CPU SSF Main Storage Synchronous
Feature 2703 5/360 CPU "- 56.1

switched or private communications facilities are
used). If the transmission is to be via private line,
the command ends immediately, upon enabling the SF and the line, with Channel End and Device End
status (CSW bits 36 and 37).
If the transmission is to be via switched network,
the command ends with Channel End and Device End
status when the local data set is operationally
available.
This command permits the SF to be in condition to
answer dialed "calls" from remote station, if
required. No data is transferred in either direction
by this command.
Dial
This command permits automatic dialing of a remote
BSC-equipped station. If the Autocall feature (ACF)
is not installed, the Dial command will be rejected
the completion of the data communication with the
remote station, the dial operation is normally ter­
minated by the issuance of the Disable command.
If the Automatic Calling Unit is nonoperational,
sense-bit 1 (Intervention Required) is set to one and
the command is ended with Channel End, Device End,
and Unit Check status (CSW bits 36, 37, and 38).
Disable
This command is used to reset the line; i. e., it
deconditions the enabling of the line originally pro­
vided by the Enable command.
Disable CON 2F, f1, fa f3
[
2F Data Address
o 78 31 f" f" h Count J I 29 I 32 3940 4748 63
Data Address . """0------'78-------------------1
31 If operating on a switched network, the execution
Count
32 3940 4748
with a Command Reject (sense-bit 0 set to one) and
will also result in setting Unit Check status (CSW
63
bit 38). When Dial is executed, bytes are transferred
from main storage to dial equipment (provided by
common carrier) at a data rate determined by the
dial equipment.
The transferred bytes represent the dial digits
required for switching purposes. All dial codes are
regarded as decimal digits and are stored in main
storage, one dial digit per byte location. The SF does not check if the characters transmitted under a
Dial command are valid dial digits, as only the four
low-order bits of the dial-digit byte are transferred
to common-carrier equipment.
The Timeout sense bit (bit 7) is set to one if the
common-carrier equipment does not signal the ACF
of successful completion of the dial operation within
the recommended 40 seconds. This timeout duration
is initiated by the transmission of the last dial digit
to the common-carrier equipment. The command is
immediately ended with Channel End, Device End,
and Unit Check status (CSW bits 36, 37, and 38).
Successful completion of the Dial command results
in Channel End and Device End status (CSW bits 36
and 37).
The Dial command can be command chained (CCW
bit 32 set to one) to a Write or Read command. At
of the Disable command terminates an outstanding
call. If operating on a private line, this command
ends immediately with Channel End and Device End
status (CSW bits 36 and 37).
When disabled, the line will not answer any
incoming calls. Note that, following a Disable
command, a Set Mode command must be issued before
enabling or dialing. Prepare This command may be used in contention-type
communications systems to indicate when data is
arriving and to thus monitor the received data stream
Prepare CON 06, fit f
2
, f3 06 Data Address
o 78 31
Count
32 3940 4748 63
for SYN characters. The Prepare command will be
accepted only if the line has been previously enabled.
No data transfer to main storage occurs during the Prepare command execution.
The Prepare command ends when a sync pattern
has been detected and sets the Channel End and
Device End status (CSW bits 36 and 37).
57