Commodore 16 - Page 85

APPENDIX
B
Disk Error Messages
These error messages are
relumed through the
DS and DS$
reserved variables
NOTE
;
Error message numbers less
lhan 20 should
be
ignored
with the exception ol
01 ,
which gives
inlormation
about the
num-
ber of
tiles scratched with the
SCRATCH command
20
21
22
23
24
READ
ERROR
(block header not found)
READ ERROR
(no
sync character)
READ ERROR
(data block not present)
READ ERROR
(checksum error
.n data block)
READ ERROR
(byte decoding
error)
The
disk
controller is
unable to lo-
cate
the header ol the requested
data block
Caused by
an illegal
sector
number, or the header has
been
destroyed
The disk controller is unable
to
detect a sync mark on the desired
track
Caused by
misalignment
of
the read/writer head,
no diskette
is
present, or unformatted or im-
properly sealed diskette. Can
also indicate
a
hardware
failure
The
disk
controller
has been re-
quested to
read
or
verify
a
data
block that
was not
property
writ-
ten This error message occurs
In conjunction with the
BLOCK
commands and indicates an ille-
gal track and/or
sector request
This error message indicates that
Ihere is
an error in one or more
ol
Ihe data byles The data has been
read
Into the DOS memory, but
the
checksum over the
data
is
tn
error
This message
may
also
in-
dicate grounding
problems.
The
data
or header
has been read
into
the DOS
memory,
but a
hard
ware error
has been created
due
lo an
invalid
bit pattern in the
data
1 !
1
r
1
r
1 i
1 i
1 i
1
1
'
)'
1 i
1 i
1 i
1 (
!
i
( i
1 I
1 i
1
i
1 i
1
1
r
1
i
1
I
1 f
1
i
25
26
WRITE ERROR
(write-
verify error)
WRITE PROTECT
ON
27
READ ERROR
(checksum error
in header)
28
WRITE ERROR
(long data block)
29 DISK ID MISMATCH
30
SYNTAX
ERROR
(general
syntax)
byte
This message
may
also
indicate grounding problems.
This message
is
generated il the
controller detects a mismatch
between
the
written data and ihe
data
in the
DOS
memory
This message is generated when
Ihe controller
has
been requested
to
write
a data
block white the
write protect switch is depressed
Typically this is caused by using
a diskette with a write protect
lab over the notch
The controller has delected an
error in the
header
ol the re-
quested daia
block
The
block
has not been
read into
the DOS
memory
This message may
also
indicate grounding
problems
The
controller
attempts to detect
the sync
mark
ol the next header
after
wnting a
datablock. If
the
sync
mam
does
not
appear within
a
pre -determined time. Ihe
error
message is generated The
error
is
caused by a bad diskette
formal
(the
data
extends into
the
next
block), or
by
hardware failure.
This
message
is
generated when
Ihe controllei has been requested
to access a
diskette which has
not been initialized. The message
can also occur II a diskette has a
bad header
The DOS cannot interpret the
command sent lo the command
channel Typically, this is
caused
167