Directory Program
The DEDICATE control statement specifies that a real device is to be
dedicated to this user. 3330V (virtual 3330) volumes may be
specified via the DEDICATE statement. If the device is a unit record
device, input and output are not spooled by A real device may be
dedicated to only one user at a time. Should a device be specified as
aedicated in more than one directory entry, only the first user to log
on gains access to it. The format of the DEDICATE control statement is: , Dedicate cuu { rdev I[VOLID] volser} [R/O] [3330V] L-- ________________________________ . ________________________________________ cuu is the virtual device address (1-to 3-hexadecimal digits).
rdev is the real device address (1-to 3-hexadecimal digits). VOLID is the required keyword used if the volser is less than four
characters long. It is optional if volser is four, five, or
six characters long.
If the VOLID operand is used, the volume must be attached to
the system when the user logs on. When he logs off, the
operator can then detach the volume from the system.
volser is the volume serial number of a disk pack mounted on some
real disk storage device (1-to 6-alphameric characters) or of
an volume to be dedicated to the virtual machine. R/O 3330V specifies that the virtual
status. If this operand is
read/write.
device is to be in read-only
omitted, the status defaults to
specifies that
and attentions
all interruptions, including cylinder
received on the rdev are to be passed
faults
to the virtual machine in its cuu.
1. When you dedicate a 2305 device, both the real and virtual device
addresses must specify the first exposure on the 2305 (that- is,
device address 0 or 8). When you dedicate a 2305 or detach a
dedicated 2305 from a user, all 8 exposures are processed.
2. Use caution in defining the hexadecimal addresses of virtual
devices (cuu) in DEDICATE statements, in order to avoid a usage
conflict caused by control unit I/O interface protocol. The
following is an example of a virtual machine's DEDICATE statements
that can cause operational conflict.
DEDICATE 10E 30E (30R is a real 3211)
DEDICATE 10F 30B (30B is a 2400 tape device)
The virtual addresses of both the 3211 and the _tape device indicate
the use of the same channel and control unit. By definition the
devices are virtual and therefore will share one virtual control
unit (VCUBLOK) in CP. A real 3211 printer operates on a nonshared
subchannel, and the real 2400 device is designed for shared
subchannel operations. Both of these real devices are mapped to
the same VCUBLOK. Thus, the subsequent processing of a channel Part 2. Defining Your System 211

Directory Program
program involving these devices can result in a hung or busy
condition (caused by a conflict in real-to-virtual I/O processing
through the common VCUBLOK). Therefore, when defining devices, make sured 11 the devices are defined (and separated) within their
own control unit range and not shared with other devices.
DEDICATE OB8 OBO is a DEDICATE statement for a device at real address OBOe Its
virtual address is OB8. DEDICATE 250 "YPACK is a DEDICATE statement that defines, for this virtual machine,
virtual address 250 as the real device where DASD volume MYPACK is mounted. Sin("C? 'tbC?rC? is no C"0n't!"01 l!ni't 0!! r,:acll for console it should be noted that this restriction applies to any
system console such as the 3138, 3148, and 3158.
This restriction also applies to SPOOL statements and combinations
of DEDICATE and SPOOL statements.
3. When the real device is a 3330V, the action VM/310 takes in
processing the DEDICATE statement at logon time depends on the
combination of operands specified. Following are the allowable
combinations and the control program action for each:
DED cuu rdev
The real device must have the VIRTUAL feature (not SYSVIRT). The
real device will be dedicated to the virtual machine as virtual
device cuu, which is a 3330-1. All cylinder fault activity on the
rdev will be processed by VM/370, transparently to the virtual
machine.
DED cuu rdev 3330V The real device must again be a VIRTUAL 3330V. All cylinder faults
and unsolicited interrups received by V"/310 on the rdev will be
passed to the virtual machine.
DED cuu volser
When processing this statement, the control program will allocate
an available SYSVIRT 3330V and dedicate that real device to the
virtual machine as virtual device cuu. The "SS volume having volser
will be mounted on the real device, and the virtual device will be
a 3330-1. This form of DEDICATE is used to dedicate volumes to non-MSS operating systems, such as CMS, since the control program
chooses the real device address and no cylinder fault interrupts
are passed to the virtual machine.
DED cuu rdev volser
The difference between this example and the one immediately
preceding is that in this case the real device address is
preselected and must have the VIRTUAL feature. This format allows
the installation to control which real devices are dedicated to
virtual machines, rather than having the control program choose a
device address when the statement is processed.
212 IB" VK/370 Planning and System Guide