is the name of the operating system supplied with the Amstrad
PCW - the software which enables the PCW to read and write things to
disc as well as service other bits hung on to the computer such as
printers. CP/M thereby enables the PCW to operate as a conventional computer (or at
least one of the 1980's) and so set it apart from other
dedicated word processors. A wide range of software soon became available
for the PCW, ranging from accounts to payrolls, databases to desk top
publishers, spreadsheets to family tree makers ... and some
games. One could even write one's own programs using the supplied
Mallard version of the Basic programming language developed by
the years, its slowness and restricted capacity have meant that most
users of the PCW as a pure computer have migrated to PC's or Macs but
it still has a useful role to play in this mode, if nothing else, to
support its prime use for word processing using LocoScript. A
couple of the programs
which do this are covered below - PIP and Disckit.
Start the PCW in CP/M
PCW in 'computer mode' by
switching on, inserting the CP/M system disc and waiting until the "A prompt"
appears. On the 9512, this will take a few moments because a few
'helpful' preparatory commands are obeyed during start up. To stop
this happening (as is desirable when DiscKit is to be used for disc
copying), hit the Stop key a couple of times as soon as the 'CP/M
version' legend appears at the top of the screen.
in the A> 'prompt' means that unless you specify otherwise, any command
to load a file or program will first be directed towards (or
"default" to) the A drive
and > is a prompt to indicate that it is waiting for you to type in something ('enter a command').
Just as with DOS on
PC's, this may be entered in upper or lower case - it matters not -
commands at this prompt must be followed by either Enter or Return to signify the
end of the command (these two keys being synonymous in CP/M, unlike
you now type in just DIR[Return] you will get a DIRectory list of the
files on drive A because, without any explicit instruction to do
otherwise, it operates on the "default" drive as shown by
the prompt. To
switch the 'default' drive from A to M, simply type M:[Return] and the prompt will
change to M>. Now repeat the DIR and a different list - those
on M - will appear. To obtain a list for a drive other than the
default, you have to be explicit so, with the default
now as M, to obtain a list for drive A, the command becomes DIR A:[Return].
Note the space between the Command (DIR) and its 'parameters' (ie A:)
and that a colon is the computer shorthand for 'drive'. As with DOS,
you must enter the colon when referring to drives - otherwise it will
think you are talking about a file called A or M - but, unlike DOS,
the colon does not appear in the prompt (ie just A> rather than
- The second drive on a twin drive PCW is addressed as drive B so, to
obtain a directory listing of a disc in that drive, type in DIR
B:[Return]. Note that if you do this on a single drive PCW, you will
be invited to "load the disc for Drive B". This does NOT
mean that you do have a second drive hidden in the bowels of the
machine somewhere (!), it merely allows sequential access to two
different discs in the same drive so uses A & B 'drives' as a way
of keeping track of them both.
Loco, there is no key to hit to tell CP/M that you have switched
discs in a drive. In theory at least, it should sense a disc change
so, the first time a new disc is accessed, you should hear the characteristic
'bomp bomp' sound of the directory being read. However, this does not
always seem to happen and because the disc directory is copied to
memory to speed access, a DIR command can list the contents of the
previous rather than current disc. A tad confusing! Repeating the
command and/or re-setting the disc usually restores the knickers to a
less twisted state.
- When switching between single density (180k) and double density (720k) discs in a 720k drive (like the B drive of an 8512), you may
well be treated to 'Disc Address Mark Missing' for track 1 (the
directory track) so be fooled into believing that the disc is faulty.
Perseverance with a mixture of R to Re-try, I to Ignore and
re-setting the disc usually does the trick.
about everything you type in at the A> prompt will be a command to
load & run a program of that name, programs being recognised by
having .COM as the last part of their name (the 'file extension').
Hence entering PIP[Return] is a command to load Pip.Com from the
default drive then run it, so it follows that the program file of the specified
name should be available on the disc in that drive. However,
prefacing the command with the drive letter enables you to load the
program from a different drive without having to disturb the current
default drive eg M:PIP loads and runs the program from drive M
without affecting the default drive or the disc thatís in it. Part of the
9512's CP/M start-up process is to run PIP to copy itself
plus a couple of other useful programs from A to M. This enables you
to run PIP with M:PIP at any time during the session without having to switch
discs in A to the one with that program on it - very useful !
supports up to 16 Groups - or "Users" as they are usually
referred to in CP/M lingo. These are
numbered from 0 to 15 but, unlike LocoScript, the vast majority of
CP/M software only ever uses User 0 for its files. This is the
'default' user so 0 does not need to be specified as a qualifier to
the drive letter in commands except on very rare occasions which need
not bother us here. However, different Users do come into play when
dealing with LocoScript discs in programs like PIP (see below) and
the references to them must be by their Group number and not any name
have been called in Loco. This can easily be worked out from
Loco's Disc Manager Screen as Groups 0-3 are down the left hand
column of the drive summary and 4-7 down the
programs from drive M - getting a Full Directory Listing
obtain a list on screen of all the files - including Limbos -
on a disc in drive A (rather than just Group 0 as was done above),
enter the command:
A:[users=all] then hit the Return
that the M: has been specified this time. This is for two reasons:
is one of four commands which, in their simplest form, can be
handled by CP/M without recourse to running the named program.
These are called 'built-in' commands so typing in just DIR or DIR
M: as was done at the start did not actually need the program
disc in the drive at the time. However, as soon as anything
complicated is entered, like stuff in square brackets, the full
program needs to be loaded and run.
running programs from drive M, disc swapping is minimised and, on
single drive PCW's, makes things possible that otherwise would
not be eg a full directory listing for any disc which didn't have
Dir.Com on it!
can be run in two ways:
entering PIP at the command prompt followed by a space then
details of the files(s) to be copied in one hit eg PIP M:=A:PIP.COM.
PIP to perform several different tasks in one 'run' of the
program. The prompt changes to an asterisk to denote that one of
PIP's commands must now be entered. When successfully completed,
another asterisk prompt will appear. To terminate the run and
return to the normal CP/M command prompt, just hit the Return
latter is recommended and assumed here .... so just type in PIP to
is the opposite to the DOS copy command so does take a little getting
used to. It takes the form:
Destination(s) = to the Source(s)
M:=A:PIP.COM will copy the PIP program from drive A to drive M.
supports the ? (any single character) and * (any number of
characters) 'wild cards' so
will copy all files on drive A to M
M:=A:*.COM will copy A to M only those ending in .COM
M:=A:A*.* will copy A to M only those starting with the letter A
This is all
very well but it only addresses User 0. What about the others, which
may well arise when dealing with discs from Locoscript? This is where
the [Gn] parameter comes in, the n representing the Group number.
will copy all files from Group 7 of A to 1 of M
so is very
useful when reorganising discs, especially when a disc is getting
full and you want to peel off a complete Group on to another disc
without the tedium of individual file copying in Loco. Another useful
will copy all files from (Limbo) Group 9 of A to (the corresponding
Active) Group 1 on drive B
To quit the
program and return to CP/M's command prompt after the last copy, simply
hit the Return key.
When doing a
series of PIP's to reorganise discs, it's a good idea to script out on paper your planned sequence of operation
Paste key summons back the previous command you typed. You can
either just hit Return to repeat the same action or amend it
before so doing - this saves a lot of typing when doing a series
of basically similar operations.
Have fun !
to part 1, Introduction - Back
to part 2, LocoScript
to part 4 - How to Run Disckit