AmstradCPC6128-hypertext-en-Sinewalker

Needless to say, it is possible to become quite an expert at how CP/M and all the
various utilities work, and at times, such expertise can be very useful in helping out
when we get into trouble. Most of us, however, only need to know enough to get us
started, and the rest of this chapter is designed to introduce all the features and
facilities without obscuring the vital facts with too many frills.
Whereas BASIC has its Direct Mode and the 'R e a d y' prompt, CP/M has a Direct
Console Mode and is identified by the A> or B> prompt. Certain built-in commands
are available but the majority of the 'housekeeping' work is done by loading and
running 'transient programs'. They are called 'transient' because they are only in the
computer (loaded from the disc) while you are using them, as opposed to being
built-in.
As well as standard CPIM error messages, the system also generates a number of
specialised hardware error messages which can be distinguished by the fact that they
normally appear on the bottom line of the screen in a 'banner' form.
CP/M Plus on the disc
The major part of CP/M Plus resides in a special file which has the filetype ' • EMS',
and is found on Side 1 of the system discs package. The computer loads CP/M from
this file into the memory using a two stage process.
Initially, the AMSDOS command I C PM loads the first sector oftrack O. On a system
disc this sector has been arranged to be a program which then loads the • EMS file
into memory. The remainder of the system tracks are unused.
Early moming start profile
During the loading process, when CP/M Plus is first activated, if the file
PRO F I LE. SUB is present on the disc, then the instructions.in that file are
SUB M I T ted. This facility can be used to re-arrange the keyboard, customise the
screen output, initialise a printer and even auto-start an application program. In
chapter 4 we saw how to rename the profile file supplied on Side 1 in order to activate
it.
While the profile file is working, a small temporary file is opened on the disc, which
must therefore be write-enabled. This is why the master disc itself cannot include a
recognisable profile file.
Chapter 5 Page 18 AMSDOS and CPIM