The first is the most 'proper' form, the second being an abbreviation for it. The

*RUN command causes the file to be loaded into memory and executed. The

named file is sought in the CSD and then in a special directory called the

library, specifically the 'Currently Selected Library' (CSL).

The third form of this command enables the MOS to intercept the request and

execute a ROM version of the program, if one exists; otherwise it continues its

search through the CSD and then CSL in the normal way. The library thus

lives up to its name by allowing disc-based extensions to the computer's

ROM-based operating system commands.

To specify the library directory to be searched, the CSL is set with the *LIB

command:

*LIB $.Library

To set the CSL to be the CSD, which in effect prevents the second search, you

can use the '@' abbreviation for the CSD, thus:

*LIB @

When the ADFS is entered using *FADFS, CSD and CSL are both 'unset'.

Typing *MOUNT sets the CSD to '$', but the CSL remains 'unset' and must be

set with *LIB.

The *LCAT command exists to allow you to catalogue the CSL quickly; it has

exactly the same effect as if you had typed *LIB followed by the full pathname

of the CSL.

More about directories

We will now look in more detail at the information printed by the *CAT

command. Suppose the following was produced:

Main disc (69)

Drive:0 Option 00 (off)

Dir.$ Lib.$.Library

BOUNCE LR(01) Capricorn DLR(03)

Games DLR(06) Library DLR(12)

TEST WR(13) XX EL(05)

The first three lines contain general information about the directory and the

ADFS, and subsequent lines give information about the individual files within

the directory.

The first line gives the title and 'Master Sequence Number' (MSN) of the disc.

The disc title is a string of up to 19 characters which usually describes what the

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