Exit Values: The data returned by DIAGNOSE X'8C' is in the following format:
Byte 0 Byte 1 Byte 2 and 3
Flags Number of Screen width
partitions in cells
Flags
80 = ext color 40 = ext highlight
20 = Programmable Symbol Sets (PSS) available
01 = 14-bit addressing
Upon completion, Rx contains:
A 4 if an 110 error occurs
A 0 if the DIAGNOSE completes successfully.
Byte 4 and 5
Screen height in
cells
DIAGNOSE Instruction in a Virtual Machine 275

CP Conventions
CP Coding Conventions
The following are coding conventions used by CP modules. This information
should prove helpful if you debug, modify, or update CPo
1.
2.
FORMAT:
Column Contents
1 Labels 10 Op Code
16 Operands
31,36,41, etc. Comments (see Item 2)
COMMENT:
Approximately 75 percent of the source code contains comments. Sections of
code performing distinct functions are separated from each other by a com­
ment section.
3. CONSTANTS: Constants follow the executable code and precede the copy files and/or
macros that contain DSECTs or system equates. Constants are defined in a
section followed by a section containing initialized working storage, followed
by working storage. Each of these sections is identified by a comment. Wher­
ever possible for a module that is greater than a page, constants and working
storage are within the same page in which they are referenced.
4. No program modifies its own instructions during execution.
5. No program uses its own unlabeled instructions as data.
6. REGISTER USAGE: For CP, in general
Register
6
7
8 10 11
12
13
14
15 Use RCHBLOK,VCHBLOK RCUBLOK,VCUBLOK RDEVBLOK,VDEVBLOK IOBLOK VMBLOK Base register for modules called via SVC SA VEAREA for modules called via SVC Return linkage for modules called via BALR
Base address for modules called via BALR
For Virtual-to-Real address translation
276 VM/SP System Programmer's Guide