I Functionl I DMKHVC DMKHVD Code IClassl Function Module Module 034 C,F Reads the system dump spool HVDRSDF file. 038 C,E Reads the system symbol table. HVDRDSYM 03C A,B,C Dynamically updates the VM/370 HVDDIRCT directory. 040 Reserved for IBM use. HVCEXIT 044 Reserved for IBM use. HVCEXIT 048 Reserved for IBM use. BVCEXIT 04C any Generate accounting cards. BVDACCT 050 A,B,C Saves 3704/3705 control program BVD3705 image. 054 Enable or disable external BVDEXPA interruptions. 058 G Virtual console interface for BVCGRAF 3270. 05C Edit message according to EMSG BVCEMSG settings. 060 Provide virtual machine storage BVCSTOR size. BVCSTOR 064 Load, find, or purge a named BVCSYS system. 068 G Virtual Machine Communication BVCVMCF Facility. 074 A,B,C Loads a 3800 named system HVD3800 into virtual storage 078 any MSS communication HVCSSS 084 B Updates in-place a VM/370 di- DMKUDU rectory control statement in
its online control block for •• 100 Start of functions specified by HVCUSER a user.
igure 26. Function Codes for DIAGNOSE Instruction (Part 2 of 2) 1-408 IBM VM/370 System Logic and Problem Determination--Volume 1

Appendix A: VM/370 Extended Control-Program Support
VM/370 Extended Control-Program SUppOit (ECPS) VM/370 Extended Control-Program Support hardware-assisted parts: (ECPS) consists of three
1. Control program assist (CP assist) defines new hardware
instructions to assist CP routines and functions or, in two cases,
as new interpretations of existing VM/370 instructions. CP assist
does not operate in a VM/370 system that runs under VM/370. 2. Expanded virtual machine assist
existing virtual machine assist.
provides an expansion of the
3. Virtual interval timer assist provides a more accurate hardware
updating of the interval timer for the virtual machine. See snQ for a list of the
processors on which Reps is ECPS INTERACTION WITH OTHER FUNCTIONS • Virtual machine assist -The expanded virtual machine assist can be enabled only if virtual machine assist is also enabled. • Program event recording -No PER events are recognized by CP assist. Virtual machine assist does recognize PER events for certain
instructions. PER events are not recognized during the updating of
the virtual interval timer. • VS1 assist
other. VM/370 ECPS and VS1 assist do not interfere with each • DOS emulator -If the DOS emulator is active, virtual machine assist
is disabled. CP assist and the virtual interval timer assist are not
disabled if the DOS emulator is active. CONTROL BY CONTROL REGISTER 6 AND MICBLOK ASSIST CONTROL FIELD
The contents of control register 6 exercise overall and absolute control
over virtual machine assist, CP assist, expanded virtual machine assist,
and virtual interval timer assist. Values in control register 6 share
control of functions provided by expanded virtual machine assist with
the setting of bits in the MICBLOK's assist control field. The use of
the assist control field is described later on under the topic "Expanded Virtual Machine Assist."
The following table defines the contents of control register 6: o Virtual machine assist enabled if on, disabled if off
1 Virtual machine in problem state if on, in supervisor state if
off
Appendix A: VM/370 Extended Control-Program Support 1-409