software and hardware are handled by the different versions
of
CP
1M
written
for the different computers. This
is
the reason why
CP
1M
has been chosen as
the operating system for the PX-S. The huge library
of
CP
1M
based software
can be installed
on
the PX-S, making it easy for the user
to
find the particular
application he requires. This increases the power and versatility
of
the com-
puter since it
is
only a machine to run software - a tool to extend the mind much
as a hammer
is
a tool to extend the body.
If
you are a beginner to computing,
CP
1M
can be a little frightening. You will
find that the terms used
to
communicate ideas to the computer are not as near
to
normal human communication as one would like. There are a number
of
jargon words which will have to be learnt. This chapter has been written in such
a way that as far as possible you only have
to
think about the current task.
If
necessary, use the index
to
direct you to the appropriate part
of
the chapter
to
find
out
about anything you do not understand. Any difficulties you
ex-
perience will disappear with practice, and you will find using
CP
1M
will soon
be second nature to you.
The only way
to
learn to use CP
1M
is
to
tryout
the examples given. This manual
cannot hope
to
cover the finer points
of
the system, but fortunately there are
a number
of
books which describe all aspects
of
CP
1M
at
all levels, from the
absolute beginner to the most advanced user. A list
of
some
of
these are given
at
the end
of
Chapter 3.
3-2
3.2 Files And File Names
In a standard CP
1M
system each drive holds floppy disks which are used to
store programs. The PX-S has some drives which do not contain floppy disks.
For
the purposes
of
using them under
CP
1M,
the RAM disks, Microcassette
drive and the ROM drives behave
as
if
they were standard disk drives. There
are a
few
specific differences, e.g. the ROM drives cannot be used to store in-
formation. The use
of
the Microcassette drive
is
described in Chapter
4.
The programs and data are stored in files. A file
is
simply a collection
of
infor-
mation which
is
related as a unit. Files fall into two main categories. Program
files are a set
of
instructions, for example a wordprocessing program. Data files
store information which
is
used by a program, for example text used by the
wordprocessor or the information used by an accounts program. Files are stored
by name. To make
it
easier
to
understand which files are which, the name
is
divided into two parts. The first part consists
of
up
to
eight characters which
are used to give a distinctive name
to
the file.
All
of
the printable characters can be used except:
< > , . ; : = ? * [ ] and the space character
The secondary part
of
the name
is
used
to
describe what type
of
file
is
stored.
Secondary names are frequently referred to
as
file types
or
extensions. This part
of
the name
is
used in the MENU
to
select the type
of
file
to
be displayed
on
the MENU in the file name area.
It
is
possible
to
store a file without an exten-
sion but this can cause problems. Applications programs frequently add the
exte~sion
to
the primary name you have given the file so that you know which
files belongs to that program. The extension
is
separated from the primary file-
name by a full stop.
Examples
of
file names with extensions are:
BASIC.COM
STAT.COM
SAMPLE.ASM
MEMO.DAT
Note that all filenames are given in upper case letters. Even
if
you type them
in lower case, they are stored
on
the disk
as
upper case.
If
you are using the
filename,
CP
1M
will understand
if
you type the file you want in lower case
or
even a mixture
of
upper and lower case. Note also that the separator in front
of
the extension
is
printed next
to
the primary file name. This may not always
3-3
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