You should always use *DISMOUNT before you remove a disc from its drive, as

this command allows the ADFS to make sure all the information on the disc is

up to date. Never try to remove a disc whilst the red light is on: you may

damage both disc and drive.

Whenever you use a program or utility on the Welcome disc you should ensure

that it is mounted and ready for use. To do this, issue the following commands

before you attempt to load or save any information:

*MOUNT RETURN

*LIB LIBRARY RETURN

The meaning of the second command will become clear later in this chapter.

Keeping files on the ADFS

The concept of a file exists to make it simpler for you to refer to information

stored on discs, which is after all invisble to the naked eye. A file is simply a

sequence of bytes (characters) that happens to be stored on a disc instead of in

the computer's memory. A file can be as short as zero bytes (an empty file) or a

little over 600K bytes long, a limit imposed by the capacity of the disc. Every

file has a name, referred to as its filename, which can be up to ten characters

long. Names can contain upper- and lower-case letters and digits (though

ADFS treats all letters as upper-case when referring to files). Certain

punctuation symbols may also be used, but because many of these have special

meanings to the ADFS it is best to avoid them for the present.

To allow you to look at the files stored on a disc the ADFS provides the

'catalogue' command, *CAT; the ADFS lets you abbreviate this to *. because it

is the command you will type more often than any other. Make sure your

Welcome disc is inserted in the drive and mounted, and then try typing:

*CAT RETURN

which should produce a table looking something like this:

Welcome             (13)

Drive:0             Option 03 (EXEC)

Di r. $             Lib. "Unset"

!BOOT       LWR(10)     LIBRARY DLR(12)

WELCOME     DLR(11)     UTILS DLR(06)

The bottom two lines show the filenames of various files stored on the disc.

Above them is some ancillary information, such as the name of the disc, which

we won't concern ourselves with now. Instead, let's try to SAVE a BASIC

program and see what happens. If you don't already have a program in

memory, then type in the following, pressing RETURN at the end of each line:

F 8