Part i 1 F I L---.I II A virtual
operator logs on
,
machine 1 I 11-------1 G 1 .- Virtual machine ECPS status is:
exp. virt. mach. assist
on,
virt. mach. assist on,
virtual interval timer
assist on II 1 Virtual machine operator I aay issue the following 1 commands: I SET ASSIST OFF 1 SET ASSIST NOTKR 1 SET ASSIST OFF NOTKR II L---.I • Virtual machine operator 1-------------------------------------------,
issues SET ASSIST OFF I II Virtual machine operator
issues SET ASSIST NOTKR II II Virtual machine operator
issues SET ASSIST OFF NOTKR II Results:
exp. virt. mach. assist
off,
virt. machine assist off,
virt. intvl. timer assist
off Virtual machine
operator issues
SET ASSIST ON .-. I H I L---J Part 4
Results:
exp. virt. mach. assist on,
virt. mach. assist
on,
virt. timer
assist off Virtual machine operator issues SET ASSIST TKR , I I G 1 L---.I Part 4
, Virtual machine I operator issues 1 SET ASSIST ON TKR I r---1 I G I L---J Part 4
Figure 27. Hardware Assist Relationships (Part 4 of 4)
,
Results: I -----------------1
exp. virt. mach. I assist off, I virtual machine I assist off, I virtual interval I timer assist off I i Virtual machine I operator issues I SET ASSIST ON TKRI r---1 I G I L---.I Part 4
Appendix A: VM/370 Extended Control-Program Support 1-415

CONTROL PROGRAM ASSIST (CP ASSIST) The following information describes the CP assist functions that are
invoked directly or indirectly by the VM/310 Control program. CP assist is part of ECPS. CP assist is hardware that assists VM/310 Control Program functions with new instructions.
Except for the functions initiated by VM/310 SVCs, all CP assist
functions are System/310 instructions. The CP assist instructions are six bytes long and are in an SS format. The format is:
o 8 16 20 32 36
T
E6 xx I B1 D1 B2 D2 E6 is the first byte of the op code for all CP assist instructions xx is the second byte of the op code and is an cp code extension
that is unique for each instruction.
Each instruction has two operands that are effective addresses
calculated from the B1D1 and B2D2 values in the normal System/310 way.
The specific instruction determines whether these operands are
data, addresses, or not used.
The following table summarizes the operation codes, instruction names, and descriptions of the CP assist instructions:
Trace Table VM/310 CP Q-E I!!§!fY£!!.Q!! E600 Yes FREE Get free storage space E601 Yes FRET Return free storage space E602 No PTRLK Lock a page E603 No PTRUL Unlock a page E604 No DECCWO Decode subsequent CCW commands E605 No UNTFR Free CCW storage E606 No SCNVU Locate virtual I/O control blocks E601 No DSP1 Dispatch a block or a virtual
machine -full function E608 No TRANBRNG Test page status E609 No TRANLOCK Test page status and lock E60A No ZAPSEGS Invalidate segment table E60B No ZAPPAGE Invalidate page table E60C No DECCW1 Decode first CCW command E60D No DSPO Main entry to dispatcher E60E No SCNRU Locate real I/O control blocks E60F No CCWGENRL Common CCW co •• and processing E610 No UNTRN Untrans1ate CSI 1-416 IBM VM/370 System Logic and Problem Deteraination--Volu.e 1