12 Errors

 A wide variety of errors can be produced by the HDFS. All of the errors
use the BBC's normal error reporting mechanism, and so can be trapped
within programs easily. The errors are described in the following
sections. The error numbers are given in the section headings, and where
possible are the same as DNFS errors.

12.1 Escape (&11)
 The ESCAPE key was pressed to abort an operation. This can only happen at
certain points; it is usually disabled during data transfer.

12.2 Bad end (&B0)
 This error occurs the end sector address given for a command is too
large, or when the end sector or memory address given is smaller than the
corresponding start address. It can also occur if a block of memory
specified by start and end addressed crosses over from the second
processor space to the I/O processor space.

12.3 Bad start (&B1)
 This error occurs the start sector address given for a command is too
large, or when the offset specified to the *FEDIT command is larger than
the file length.

12.4 Bad length (&B2)
 An attempt was made to create a directory with an invalid length, or
modify the length of a file or directory to a size too big for the
available space.

12.5 Bad range (&B3)
 An offset was specified to a command which was not between the start and
end addresses given.

12.6 Not empty (&B4)
 An attempt was made to delete a directory that was not empty. The
contents of the directory should be deleted first.

12.7 Too long (&B5)
 This error occurs when a string or sequence of hex numbers exceeds the
maximum length allowed.

12.8 Bad wild char (&B6)
 This error is produced when the command *WILD is used to try to set wild
card characters which are not all different, printable characters.

12.9 Find what? (&B7)
 An empty string was given to the *DFIND , *FFIND , or *MFIND commands.

12.10 Bad edit mode (&B8)
 The current display mode is not capable of supporting the disc, file and
memory editor.

12.11 Parameters (&B9)
 Too many parameters were provided for an 8271 controller command.

12.12 Wrong format (&BA)
 This error indicates that an attempt was made to access a disc which was
not in a valid format. This usually occurs when the reverse side of a
double sided HDFS format disc is accessed with drive numbers :2 or :3.

12.13 Not readable (&BB)
 An attempt was made to open a file for input which is not marked as
readable.

12.14 Not executable (&BC)
 A command file was *RUN which is not marked as executable.

12.15 Too big (&BD)
 The maximum size of number accepted by any HDFS command is &FFFFFFFF for
hexadecimal numbers, or 65535 for decimal numbers. This error occurs when
a number larger than these limits is specified.

12.16 Cat full (&BE)
 There are already 31 entries in the directory catalogue. Partitioning
files into subdirectories can free up some more catalogue space.

12.17 Can't extend (&BF)
 A file open for output or update has run out of the available space. This
error should occur less frequently in HDFS than DNFS, because new files
are opened in the largest gap available in a directory.

12.18 Too many open (&C0)
 Too many files were opened simultaneously; the maximum number of files
which HDFS can have open at one time is 6.

12.19 Not writable (&C1)
 An attempt was made to open a file which is not marked as writable for
update or output.

12.20 Open (&C2)
 An attempt was made to open a file which was already open, or an
operation was required which cannot be performed on open files. Operations
which move file contents cannot be performed on open files.

12.21 Locked (&C3)
 The file or directory is locked, and the operation required cannot be
performed without unlocking it first.

12.22 Exists (&C4)
 This error is issued when a file or directory specification which exist
was specified in a context in which a new name was required.

12.23 Drive fault EE at DD/TT (&C5)
 This error indicates that an error was detected with the disc drive, and
that a transfer could not be performed. The error code, drive number and
track address are given in the error message. The error code given
indicates what the error was:
	0A Late DMA
	10 Drive not ready
	14 Track 0 not found
	16 Write fault
These errors are probably unrecoverable. The first digit of the drive
number indicates which disc surface was being accessed when the fault
occurred. This may not be the same as the drive number for HDFS format
discs, which can span the front and back sides of the same disc. The
surface codes are:

 4 Surface 0 (side 1 of drive 1)
 8 Surface 1 (side 1 of drive 2)
 6 Surface 2 (side 2 of drive 1)
 A Surface 3 (side 2 of drive 2)

12.24 Dir full (&C6)
 No more space is available in the directory. If it is not the root
directory , the directory may be able to be *EXTENDed, and given a larger
length with *ATTRIB.

12.25 Disc fault EE at DD/TT (&C7)
 This error indicates that an error was detected on the disc, and that a
transfer could not be performed. The error code, drive number and track
address are given in the error message. The error code given indicates
what the error was:
	08 Clock error
	0C ID CRC error
	0E Data CRC error
	18 Sector not found

 These errors are probably worth trying again; the maximum number of
re-tries can be set using *OPT 2. The first digit of the drive number
indicates which disc surface was being accessed when the fault occurred.
This may not be the same as the drive number for HDFS format discs, which
can span the front and back sides of the same disc. The same codes as the
drive fault error are used.

12.26 Disc changed (&C8)
 The disc on which data should have been written has been changed. This
can happen when files are opened and the disc is changed, or when the
wrong disc is inserted while copying files with one disc drive.

12.27 Disc read only (&C9)
 An attempt was made to write to a disc which has its write-protect notch
covered.

12.28 Bad track (&CA)
 A track number which is larger than the current disc can support has been
used. This error sometimes occurs when HDFS double-sided discs are used
with a valid track number. In these cases, specifying the drive number to
the command should make it work correctly . This can also occur when
copy-protection schemes are used; an option to the *DRIVE command is
available to turn off track number checking for these discs.

12.29 Bad option (&CB)
 This error occurs when a *OPT command is used with the code or value out
of range. See section 11.7 for the meaning of the *OPT parameters.

12.30 Bad name (&CC)
 An invalid file or directory name has been used. Possible causes for an
invalid name are; wild card characters were used in the directory part,
the name is too long, or a directory or file name part is longer than 7
characters.

12.31 Bad drive (&CD)
 A drive number outside the range 0-3 was used.

12.32 Directory (&CE)
 A directory specification was given in a context in which only files can
be used.

12.33 Not found (&D6)
 This error is issued when a file or directory specification which does
not exist was used, in a context in which it was required.

12.34 Syntax: : : : (&DC)
 Incorrect command syntax has been used. The correct syntax for the
command is shown in the error message.

12.35 Channel (&DE)
 An invalid file handle was used; this may be because the file had been
already closed, or had not been opened successfully .

12.36 EOF (&DF)
 An attempt was made to read past the end of a file. An error flag is set
on the first attempt to read past end of file (see section 11.3) and this
error is issued on the next attempt to read.

12.37 Bad command (&FE)
 An unrecognised operating system command was issued, and it could not be
found in the current directory or library. This error is also issued by
attempts to *RUN non-existent files.