DIAGNOSE Code X'50' -- Save the 370X Control
Program Image DIAGNOSE Code X'SO' (Privilege class A, B, or C only) invokes the CP module D8KSNC to (1) validate the parameter list and (2) write the
page-format image of the 370X control program to the appropriate system
voiume. When a 370X control program load module is created, the CMS service
program SAVENCP builds a communications controller list (CCPARM) of
control information. It passes this information to CP via a DIAGNOSE Code X'SO'. The register specified as Rx contains the virtual address of the
Farameter list (CCPARK) e The Ry register is ignored on entry. Upon return, the Ry register contains the following error codes: 044
171
178
179
435 'ncpname' was not found in system name table. System volume specified not currently available.
Insufficient space reserved for program and system control
information. System volume specified is not a CP-owned volume.
Paging error while writing saved system. DiAGNOSE Code X'54' -- Control the Function of the
PA2 Function Key DIAGNOSE Code X'S4' controls the function of the PA2 function The PA2 function key can be used either to simulate an external interrupt to
a virtual machine or to clear the output area of a display screen.
The function performed depends upon how Rx is specified when DIAGNOSE Code X'S4' is issued. If Rx contains a nonzero value, the PA2 key
simulates an external interrupt to the virtual machine. If Rx contains
a value of zero, the PA2 key clears the output area of the display
screen.
The external interrupt is simulated only when the display screen is
in the VK READ* HOLD, or KORE status and the TERMINAL APL ON command has
heen issued. DIAGNOSE Code X'58' -- 3270 Virtual Console Interface
Execution of DIAGNOSE Code X'S8' allows a virtual machine to display
large amounts of data on a 3270 in a very rapid fashion. It is possible
to display the entire 3270 screen with one write operation instead of 22
writes (one for each line in the output area of a 3270 screen).
The register specified as Rx contains the address of the console CCW string. The Ry register contains (in bits 16 throllgh 31) the device
address of the virtual console.
To specify the display CCi, use the following assembler language
instructions: DS OD
DC X'19', AL3 (dataddr), AL1(flags), AL1(ctl), AL2(count) Part 2. Control Program (CP) 199

dataddr
flags
ctl
count
is the beginning address of the data to be displayed.
is the standard CCW flag field with the suppress incorrect
length indication (5LI) bit on.
is a control byte that indicates the starting output displaY' line= If the high order bit is on, the entire 3270 output display area is erased before the new data is displayed. A
value of X'FF' clears the screen, but writes nothing.
is a two byte field indicating the number of bytes to be displayed. The 3278-2A display console can display a maximum
of 1440 bytes; all other display consoles can display a
maximum of 1760 bytes. When the DIAGNOSE is executed with a valid CCW string, a buffer
(whose length is the number of bytes specified by is built in
free storage. The data pointed to by is loaded into the buffer.
Data chaining may be specified in the CCW to link noncontiguous data
areas; however, command chaining is an end of data indication for the
current buffer. Using the starting output line (ctl) and the number of bytes of
output (count), CP checks that the data will fit on the screen. CP then
does the display. A zero condition code indicates the I/O operation
completed successfully; a nonzero condition code indicates an I/O error
occurred. !Qte: An I/O error occurs when the display screen is placed in MORE status and the PA2 key is pressed to allow screen display. DIAGNOSE Code X'5C' --Error Message Editing
Execution of DIAGNOSE Code X'SC' causes the editing of an error message
according to the user's setting of the EM5G function:
Rx contains the address of the message to be edited.
Ry contains the length of the message to be edited. DMKHVC tests the VMMLEVEL field of the VMBLOK and returns to the caller
with Rx and Ry modified as follows:
, VMMLEVEL 1 Registers on Return I VMMCODE I VMMTEXT 1 Rx Ry 1----1 ON 1 ON 1 no change no change 1----1 ON I OFF 1 no change 10 (length of , , code) I I OFF I ON 1 pointer to text length of text I I part of message alone
1---1 OFF I OFF I N/A 0 200 IBM VM/370 System Programmer's Guide