Radio Shack TRS-80 Model II Reference Manual page 120

Modell! TRSDOS
Verification
FORMAT
also does a specified amount of verification, or checking for areas on the
diskette which cannot store data due to flaws in the recording surface. If it finds a
flawed area,
TRSDOS
"locks out" the affected track and will never try to use that
track.
Whenever you format a new diskette, use the
FULL
verify option. This takes longer,
but gives greater protection against lost data due to a flawed track.
When you are re-formatting a diskette which has been functioning without diskette
errors, the
NONE
option may be sufficient.
NONE
is faster than
FULL,
since no
verification is done. But remember, for greater reliability,
FULL
verification is
recommended.
Main and Alternate Directories
TRSDOS
maintains a primary directory on each diskette. Unless you use the
ALT
=
00
option,
TRSDOS
will also maintain an alternate directory.
For general applications, you should always have an alternate directory. If a
diskette's primary directory should become unreadable, the alternate directory will
automatically be used instead - so that you don't lose access to the data on that
diskette. See
BACKUP,
Using
BACKUP
to Recover Lost Data.
Selecting the Directory Tracks
TRSDOS
allows you to specify where the directories will be placed. The default
locations are:
Primary
=
44 Alternate
=
52
For general purposes, this will be the most efficient arrangement.
Notes on Directory Location
1. If you are going to put
TRSDOS
on the diskette, be sure there are seven
contiguous good tracks immediately after the primary directory.
2. The greater the spread between the primary and alternate directories, the longer
it will take
TRSDOS
to update them. A spread of 8 tracks is recommended. This
isolates the directories without separating them unduly.
3. If the diskette is to contain the
TRSDOS
system (full or minimum), there must be
seven good contiguous tracks following the primary directory. For this reason,
the primary directory track number must be less than or equal to
69.
4.
FORMAT
will not place a directory (primary or alternate) on a flawed track. If
you specify a track
(DIR
=
or
ALT
= )
which is flawed,
TRSDOS
will use the
default track
(DIR =44, ALT = 52).
If the default track is bad,
TRSDOS
will place
the directory on the first good track after this one.
TRSDOS
will abort the
operation if it doesn't encounter a good track within five tracks of the default
track.
156