Appendix 4

*FX commands

A proportion of the memory reserved for use by the MOS is given over to the

storage of information relating to the current state of the machine and how it is

to react in various circumstances. This information is directly accessible to, and

may be changed by the user by means of special operating system calls (often

referred to simply as OSBYTE calls).

Some OSBYTE calls have an equivalent *FX command which may be issued

directly from the keyboard or included in, say, a BASIC program and these

commands are summarised below. Commands marked „# provide access to

facilities required only by advanced users and full details can be found in the

Reference Manual.

Apparent gaps in the sequence relate to OSBYTE calls which do not have an

equivalent *FX command and which must therefore be implemented by means

of techniques beyond the scope of this guide.

Parameters in *FX commands may be separated by a comma (as in the

examples below) or a sequence of one or more spaces.

If a parameter is omitted it is assumed to be zero.