The real machine configuration is represented by
a set of related control blocks. These blocks are: in the VM/'nO nucleus built from macros during system generation loaded at system IPL and initialized then for
operation.
There is one control block per channel, per control unit, and per device. The characteristics of VM/370 real I/O control are: Block multiplexing (BMPX) with RPS (Rotational Position
Sensing) is I ,sed. Multi-path ·;cheduling is not used. All I/O operations are handled by VM/370 scheduling iJnd interrupt handling. .6 DMKRIOCT - real channel table
l
- . - indicates that no channel exists -positive value is an index RCHBLOK - real channel block I Channel identification Scheduling Control to the RCHBLOK XXXX I Control Unit t---+--+--t-X-X-X-X-l Index Table unit exists
if positive, that value is an hldex to the RCUBLOK RCUBLOK - real control unit block
l
Control Unit identification Scheduling Control if negative (FFFF), no
device ex ists
XXXX
XXXX
if positive, that value is
an index to RDEVBLOK e complete c:..crlptlon of CP control block •• _ IBM Virtual Mschine Fscility/3.70: Datil ArelU and Control Bloe"'. "'der No. SY20-0884. __ , __ _________________________ -J Device Index Table Relationship of R,eal I/O Control Blocks ---- DMKRIOCT (part of DMKIRIO) RCUBLOKs RDEVBLOKs Mn. t,-+--><-t-' IRDEVBl.OK - real device block' Device identification Scheduling Control Terminal Control Spooling Control Dedicated Control Error Recovery Allocation Control Part of the RDEVBLOK pertains to functions that are
device independent; that part of the RDEVBLOK is used
in the same way for all devices. However, some of the. fields in the RDEVBLOK have multiple uses, depending
on the device type and function.
- ":rJ I ,.,. - \Q 0\ .:: t1 ('I) H tIS W til: . c:z IX c:z " ,.,. W t1 -..J r+ 0 .:: PJ Ul I-' "<I rn H r+ " CO 0 EI n t"' 0 0 ::s \Q r+ ,.,. t1 n 0 t-' PJ t::I tIS ,:::a, I-' 0 0 t1 ;0r- O rn t7' I-' CO B t:1 CO r+ CO t1 &I ,.,. ::s PJ r+ ,.,. 0 ::s I I 0 ..... d CO - The virtual machine configuration is represented by a set
of related control blocks. These blocks are: built by VM/370 at LOGON from data in directory modified by user commands (for example, DETACH. LINK. DEFINE) There is one control block per channel, per control unit. and per
device .
The characteristics of VM/370 virtual I/O control are: BMPX (block multiplexing) is supported RPS (rotational position sensing) is supported the virtual machine operating system performs scheduling VM/370 uses virtual I/O control blocks to simulate real hardware interface virtual unit record devices use VM/370 Spooling virtual console is simulated on terminal minidisks simulate DASD dedicated devices are supported
VMCHTBL - virtual channel index table VCHBLOK - virtual channel block 1 Channel identification
status XXXX XXXX XXX X XXXX XXXX XXXX XXXX XXXX if negative (FFFFI. no control unit exists
if pOSitive, the value is an index
to the VCUBLOK Relationship of Virtual I/O Centrol Blocks ---------------, VCUBLOK - virtual control unit block 1 Control unit identification
status XXXX XXXX XXXX XXXX } D
. eVlce XXXX Index Table if negative (FFFF). no device
exists
if positive, the value is an index
to the VDEVBLOK VMCHTBL (part of VMBLOK) 1 VCUBLOKs VDEVBLOKs
n VDEVBLOK -- virtual device block 1
Device identification
Status pending
Positioning Terminal control Spooling control RDEVBLOK PointPr Part of the VDEVBLOK contains device independent
information and is used identically in all VDEVBLOKs.
However, some fields of the VDEVBLOKs have multiple uses, depending on the device type.
For a detaIled description of the CP control blocks, see IBM Virtual Machine Faciliry/310: Data Areas and Control Blocks. Order No. SY2Q.0884.
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