SET LINEDIT ON is specified, the buffer data is edited and translated to
EBCDIC. Ihen the read is completed, the data is aoved to the specified
user address obtained from the address portion of the virtual CCI. If coaaand chaining is specified, processing returns to fetch and analyze
the next CCI. If coamand chaining is not specified, the virtual CSI is
constructed in the VDEVBLOK and an interrupt is flagged as pending in
the VMBLOK. Ihe Irite Simulation Routine: Obtains a buffer for the construction of
the output message from free storage. The virtual aachine data is
located from the virtual CCI address in the VCONCTL block and aoved to
the data buffer. The DMKQCNIT routine is called to write the data in
the buffer and provide the necessary length, translation, and foraat
functions. Control is received at the DMKVCB aodule upon completion of
the writing. At this point, the virtual CCI is re-exaained. If co •• and
chaining is specified, processing continues to fetch and analyze the
next eCI. If comaand chaining is not specified, the virtual CSI is
constructed in the VDEYBLOK and an interruption is flagged as pending in
the VMBLOK. Control Simulation Routine: Is used for the NOP and ILIBM operations. A lOP operation requires no data transfer or I/O operation.
An ALARM operation has no equivalent on low-speed teleprocessing
equipment; thus, a aessage indicating the ALIRM operation is
constructed. DMKQCNIT is called to output the constructed message. If
the command is chained, processing continues (for HOP or ILARM) to fetch
the next eCI and analyze it. If command chaining is not specified and
this is not the first CCI, a virtual CSI is constructed in the VDEVBLCK and an interruption is flagged as pending in the VMBLOK. If this is the
first (and only) CCI, then a condition code of 1 is presented with
channel end and device end in the virtual CSI. A Virtual Sense Operation: Is similar to a control operation, because no actual-r,o--operation is perforaed. However, there is data transfer.
The sense data fro. the VDEVBLOK is moved to the virtual storage
location specified in the virtual CCI address. If the coaaand is
chained, processing continues to fetch the next CCI and analyze it. Otherwise, an interruption is flagged as pending in the VMBLOK. virtual CCI addressed by the TIC
If the fetched CCI is itself a
channel program check condition
as an interruption or as a ! Yirtyal TIC tio1!: Fetches the
address and analyzes the fetched CCI. TIC, or if the TIC is the first CCi, a
is reflected to the virtual machine CSI-stored condition, respectively.
Invalid Opera!!on: Any other operation is considered invalid. Coaaand reject status is posted in the virtual sense byte and the operation is
terminated with unit check status presented in the virtual CSI. REMOTE 3210 PROGRAMMING For a basic understanding of CP processing of data relating to 3270 devices on binary synchronous lines, the inforaation and terminology
contained in 18ft 327Q !nformati21! DisplaI Coaponent Description,
and General !1!formati21! - Synchronous Communications is required. I digest of SOme of this essential information as it applies to YM/370 follows:
CP Introduction 1-97

• Text messages to and from remote terminals and printers can only be
achieved when the bisync line is in text mode. • Text messages from a remote device can be the result of a general
poll or specific poll operation to the related device or devices on
the bisync This polling communication interface is
accomplished by each line-connected control unit having unique
specific poll and general poll recognition circuitry and by the CP terainal list of valid bisync lines and 3270 remote control unit
addresses. This list, the terminal list, is generated by VM/370 system generation procedures employing TERMINAL and CLUSTER macros. For more details about terminal list generation, see the g.!l£ • Reliability and dependability of line operation is achieved by the
use of: a double addressing scheme, control characters with a rigid
message protocol, and complex redundancy-check characters appended to
transmission messages. Examples of these techniques are shown in the
formats that follow. • Every message (text or that is by CP may .ay not be responded to by the remote station or control unit. The type of
response (or absence of response) that CP receives depends on the
receptiveness of that device or control unit to the previously sent
message (is the device ready and enabled and accurately addressed)
and the content and correctness of the aessage (no line errors). • To establish the relationship of the line of terminal response to a
particular line or device write or read operation, CP employs an
operation "tracking" facility (TP op code) imbedded 1n the issued CCWs. The function performed by the CP op code is described in the
following CCW formats. I IOperationl Address IFlags ITP Op 1 Count 1 Code 1 Field 1 1 Code I 1 I 1 byte 1 3 bytes 11 by tell bytel2 bytes 1 I o 7 8 31 32 39 40 47 48 63
Operation Code
contains the hexadeciaal value of the type of operation
perforaed by the command. Valid operation codes are: X'01' WRITE X'02' READ X'03' NO-OP X'09' POLL 1'23' SET MODE X'27' ENABLE X'2F' DISABLE
Address Field
Depending on CCW usage, this field may address an:
1-98 IB" '"1370 System Logic and Problem Deteraination--Volu.e 1