Area
Table
The address of the data area (read buffer) located in the BSCBLOK at BSCREAD.
The appropriate location in the table of data-link control
characters provided in the module D8KGRF (Exaaple: ENQ).
Response
List (BSCRESP). The address location of the response aessage in
the BSCBLOK. The appropriate entry in terminal list (NICBLOKS) associated
with the READ or WRITE operation. The entry for WRITE operation is at location BSCSEL. The entry for the READ
operation is at location BSCPOLL. Note: To see how the key words AREA, and LIST are refer to the CCW sequences described in "I/O Program Routines for Bisync
Lines and 3270 Remote Devices" in this section.
Flags
TP op Code Count
The flag bits turned on in the CCW: CC (channel CD
(chained data), SILl (suppress incorrect length skip (suppress data transfer to main storage) and PCI (progra&-controlled interrupt).
An imbedded teleprocessing operation code in the CCWs used in
bisync line communications. This code is inspected by the
secondary interruption when channel end and
device end are received. The code is also used by the error
processing module, DMKBSC. The code indicates the function
being performed by the associated command. For use of the TP op codes, refer to the formatted CCWs that follow.
Refers to the byte length of the CCW READ or WRITE operation. 1/0 PROGRAMS FOR BISYNCHRONOUS LINES AND REMOTE 3270S Before data communication to re.ote 3270 equipment can take the
re.ote teleprocessing line, the control unit and the device(s) .ust be
enabled for co •• unication. This occurs when control unit hardware
recognizes a unique string of characters transmitted on the line from CP. Disabling a line occurs in a siailar .anner. The following is the
format of the CCWs used in the enabling/disabling operation: CP Introduction 1-99

• I IOpera- ICommand I I ITP Opl I Ition I Code IAddress IFlagslCode ICount 1--------------------------------------- I D i s-I' 2F' 0 lable ILine CC, I SILl 1 I 01 1
1--------------------------------------- ISet 1'23' 1'40' CC, I 01 1 !Mode SILl, 1------------------------------------------ IEnablel 1'27' 0 SILl I 01 1 ILine 1 I 1 IOpera-ICo •• andl I ITP Opl I Ition 1 Code IAddress IFlagslCode ICountl 1--------------------------------------1 I Dis- I' 2F' 0 SILl I 01 1 1 lable I I ILine I I , After a line is enabled, communication can then be directed to a
particular resource. The sequence of events (for a write disable and
write continue) is as follows: Send a data link control character on the line that places the
control unit in control .ode. This .ode makes the control unit
receptive to the specific address indicated by the second CCI. The
third CCI is a read CCI that is needed for the acknowledge.ent response from the addressed control unit. Normally, in response, CP trans.its a
block of data to that device with a write text CCI. Acknowledgement of
receipt of this data is contained by the read response (write continue) eel. The format of the CCI write initial and write continue operation
follows. !rite !nit!g.! I Opera-ICo •• and I I ITP Opl I tion I eode IAddress IFlagslCode I Count Write I 01 Table ce, I 02 1
an EOTI SILl I Write I 01 List ee, I 03 ILIST ad- I SILl I I dress-I I I ing I I I char. I I I Read 02 IResponse I SILl I 05 2
Re- I I I I I sponse I I I I I 1-100 IB! VM/370 System Logic and Problem Deteraination--Volume 1