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Atom DOS commands
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*DOS (*D.)
Enters the Disk Operation System. The COS is re-entered on BREAK. Note:
In the ATOM emulator the COS can also be re-entered by typing *COS.

*DRIVE <drive number> (*DR.)
Selects drive number without reading the catalogue.

*CAT [drive number] (*.)
Displays the catalogue. The first line shows the title of the disk and
the current qualifier. The filenames are displayed arranged by qualifier,
with the '#' indicating that the file is locked.
The catalogue is read off disk unless the disk is in the 'ready'
condition (still spinning), in which case it is transferred from the
catalogue buffer (at 2000h).

*DIR [drive number] (*D.)
Reads the catalogue from disk to the buffer, but does not display it.
This command is often used to wait for completion of a previous
operation, since the prompt may re-appear while a transfer continues
under interrupt.

*TITLE <title> (*T.)
Sets the title of the disk to the first 13 characters of <title>.

*SETx
Sets the qualifier for all subsequent operations on files to x.
Operations that use the existing files will only search among those
created under the qualifier currently set. The default qualifier is
space. When returning to the default qualifier, be sure to enter space
after the set command.

*USEx
Temporarily sets the qualifier to x. The system returns to the previous
qualifier after the next successful operation. Two successive USE
commands are equivalent to a SET.

*LOCK <name>
Locks the named file. Locked files cannot be deleted or updated.

*UNLOCK <name> (*U.)
Unlocks the named file.

*INFO <name> (*I.)
Displays information about the named file. The format is:
qualifier : lockstate filename loadaddr execaddr length startsector
For example:
s: #BASIC C000 C2B2 01000 002
The '#' indicates that the file is locked.

*MON (*M.)
Turns on messages. Subsequent file operations print out the file's
information in the format of *INFO.

*NOMON (*N.)
Turns off messages.

*SAVE <name> aaaa bbbb cccc (*S.)
Creates a file. The contents of memory from aaaa to bbbb-1 are saved as
the named file. If a file with the same name already exists under the
current qualifier, it is deleted. The address cccc is an optional
execution address and it defaults to aaaa is not supplied.

*LOAD <name> aaaa (*L.)
Loads the named file. The file is loaded into memory starting at aaaa,
or at the file's start address if this is missing.

*DELETE <name> aaaa (*DE.)
Deletes the named file.

*GO aaaa
Executes the machine-code subroutine at aaaa.

*RUN <name> <string> (*R.)
Load and run the named file, using the start and execution address.
<string> is transferred to memory starting at 0140h with a terminating
CR, where it can be accessed by the user's program.

*EXEC <name> (*E.)
Executes the named text file as if it had been entered at the keyboard.

*SPOOL <name>
Outputs all data from keyboard first to the named file, and then to the
screen.

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DOS responses and error messages:
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Command?
The command is not recognised.

Syntax?
The paramters are illegal or incorrectly presented.

Name?
The filename is longer than seven characters.

File?
The file is not found.

Disc prot
The disk is write-protected.

File prot
The file has been locked.

Disc full
There is insufficient room on the disk to create the new file.

Full
There are already 31 files in the catalogue.

Disk error 08 (Clock error)
During a disk read operation a clock bit was missing.

Disk error 0A (Late DMA)
During a disk transfer the processor did not respond fast enough.
Probably due to a faulty disk controller card.

Disk error 0C (ID filed CRC error)
The cyclic redundancy check derived from the data read back differed
from that stored on the disk.

Disk error 0E (Data CRC error)
The cyclic redundancy check from the data read back differed from that
stored on the disk during a disk read.

Disk error 10 (Drive not ready)
During a transfer the disk stopped rotating. Often due to a badly
inserted disk.

Disk error 14 (Track 0 not found)
The controller failed to find track 0. Often due to an unformatted disk.

Disk error 18 (Sector not found)
The controller failed to find the required sector. Often due to a
corrupted or unformatted disk.