tcl.t-select Verb: Access/Tape Commands


Command tcl.t-select Verb: Access/Tape Commands
Applicable release versions: AP 6.1
Category Tape Commands (36)
Description attaches a "tape" device to the current process.

"tape" devices include floppy diskettes, streaming cartridge tape (sct), half-inch, 2mm cartridge tape, 4mm dat devices and "psuedo-floppies" such as communication ports and inter-virtual-machine files.

This verb is the root command from which "set-floppy", "set-sct" and "set-half" operate.

If no options or parameters are specified, "t-select" displays all devices defined for the system and prompts for a selection.

"device.num" may be expressed as a numeric literal. This number must be a numeric integer between 0 and 15 and correspond to a predefined tape device. On Unix-based systems, these devices are defined in the system configuration file. If a comma separates more than one device.num then they are linked together. See t-link verb.

"keyword" may be any combination of characters (except numeric integers between 0 and 15) appearing in the "TYPE", "DENSITY" or "DEVICE NAME" columns of the "t-stat" verb. These keywords are used to try to pinpoint the desired device from a captured list. On some systems there may be more than one of a particular device (two 5-1/4" floppies, for example). If there is not sufficient uniqueness in the parameters, the process will always find the first floppy.

On Unix implementations, if there is more than one floppy drive, and one of them is a 5-1/4" floppy, the 5-1/4 is always designated as drive A. If no other parameters but FLOPPY are given, the verb will assume drive A, 5-1/4" high density floppy.
Syntax t-select
t-select {?}
t-select {device.num} {,device.num} {(options)}
t-select {keyword} {(options)}
Options 3 3-1/2" floppy.

5 5-1/4" floppy.

9 9-track, 1/2" tape.

a 5-1/4" floppy.

b 3-1/2" floppy.

c Changes the 8mm tape block size. The current tape block size is displayed and the operator is prompted for the new block size (0 or 512). On AP/Unix Systems, the default block size is set at "0" (zero) at install time. Zero means variable-length.

f Floppy (3-1/2" or 5-1/4" as default)

h High density (1.44M for 3-1/2" floppy, 1.2M for 5-1/2" floppy, 6250 bpi for 9-track tapes, 150M for Quarter Inch tapes).

i Suppresses display of devices after the command is complete (used in macros).

k Hard disk "pseudo" tapes. These devices are removable or fixed hard disks or regular Unix files. Their size is fixed and determined by the device or by the maximum file size for a user. The main usage for these devices is for small, fast t-dumps/saves, transaction logging or incremental saves.

l Low density (720K for 3-1/2" floppy, 1600 bpi for 9-track tapes).

m Medium density (720K for 5-1/4" floppy, 3600 bpi for 9-track tapes).

n Network "pseudo" tape. This device has an 'infinite' size. It is assumed another system is reading the data at the 'other end' of the network.

q Quarter Inch tape.

s Standard density (360 for 5-1/2" floppy, 60M or 120M for quarter-inch (SCT) tapes.

w Prevents an automatic rewind on the device. This option must be used to set the device to a floppy with an unformatted floppy disk in the drive.
x Default block size
Assume the following device list for all examples:

Tape Status
#   Type                 Density             Device Name
0   floppy               3-1/2" 1.44m        /dev/rfd0h
1   floppy               3-1/2"  720k        /dev/rfd0l
2   floppy               5-1/4"  1.2m        /dev/rfd1.15
3   floppy               5-1/4"  360k        /dev/rfd1.9
4   quarter inch         high (350m)         /dev/rmt2.1
5   quarter inch         standard (120m)     /dev/rmt2.5
6   floppy               infinite            /tmp/floppy

The following statements all attach the 5-1/4" floppy, high density:

t-select 2
t-select floppy  (by default and for compatability)
t-select floppy (a  (by Unix convention)
t-select 1.2m
t-select /dev/rfd1.15
The following attach the 3-1/2" low density floppy:

t-select 1
t-select floppy (b
t-select 720k
The following attach the psuedo floppy disk file called "/tmp/floppy" 
on a Unix-based system:

t-select 6
t-select floppy infinite
t-select /tmp/floppy
Related tcl.t-stat