Guardian Application Conversion Guide

Identifying Disks and I/O Devices
System Compatibility
C–2 096047 Tandem Computers Incorporated
Identifying Disks and
I/O Devices
A process uses a file name to identify a disk volume or an I/O device such as a printer
or tape drive. An unconverted process can use eight-character file names (one to
seven characters after the dollar sign) to identify local disk volumes or I/O devices.
However, an unconverted process cannot use an eight-character name to identify
remote disk volumes or I/O devices.
Using D-series file names, a converted process on a D-series system can identify local
or remote disk volumes or I/O devices with eight-character names if they are on other
D-series systems in the network. However, a converted process on a D-series system
follows the C-series file-name identification rules when accessing remote C-series
systems: it cannot identify remote disk volumes or I/O devices with an eight-
character name if they are on C-series systems in the network.
Figure C-2 shows the use of eight-character file names to identify disk volumes and
I/O devices in a network.
Figure C-2. Identifying Disk Volumes and I/O Devices
Low PINs
(0-255)
System \CENT
(C-Series System)
Low PINs
(0-254)
System \WEST
(D-Series System)
System \EAST
(D-Series System)
Low PINs
(0-254)
$DISKVOL $LINEPTR
$DISKVOL $LINEPTR
Disks and I/O devices that cannot be identified
from a process on system \WEST or \EAST
using 8-character D-series file names, but can
be identified by a process on system \CENT
using 8-character C-series file names.
Disks and I/O devices that can be identified
from a converted process on system \WEST or
\EAST using 8-character D-series file names.
$DISKVOL $LINEPTR
High PINs
(≥ 256)
High PINs
(≥ 256)