Screen and keyboard effects

The MOS provides several commands which enable you to affect how the

computer communicates with the user. The first of these, *SPOOL, directs a

copy of all the computer's output which appears on the screen to a named file on

disc. This is achieved by issuing a command such as:

*SPOOL screen

in which case all screen output will be copied to the file until the command:

*SPOOL

(without a filename) is executed. This is useful for keeping a record of the

output a program has produced, particularly when it fills several screenfuls.

The *TYPE command displays the contents of such a file on the screen,

'replaying' the recording made with *SPOOL. For example:

*TYPE screen

An alternative form to this command, *LIST, displays the file in the same way

but adds line numbers (from 0001 upwards) at the start of each displayed line.

A command which has roughly the opposite effect of *SPOOL is *EXEC. This

reads in the contents of a named file as if it had been typed at the keyboard,

disabling the keyboard whilst this takes place. Because the ADFS knows the

length of the file (from its directory information) \you do not need to stop *EXEC

explicitly, though pressing ESCAPE will do this if you so desire.

The *BUILD command creates a file containing lines of text typed at the

keyboard, suitable for subsequent *EXECing. If you type:

*BUILD Droid RETURN

the computer will respond with:

0001

and store what you type in the file 'Droid' (without the line numbers, which are

displayed simply to aid you). Each line must be terminated by pressing RETURN,

and to tell the computer you have finished you should press ESCAPE. You may

have noticed that the *LIST command is the precise reverse of this.

The *BUILD command is a handy way of storing sequences of commands you

often have to type, for example to define the contents of function keys. You may

also like to know that any line of text preceded by '* |' is ignored by the

operating system, for example:

*BUILD keys RETURN

0001 *| My function key definition file RETURN

0002 *KEY 0 OLD:||MLIST ||M RETURN

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