Read-me for CMDP.IMG
====================

CMDP.IMG is a copy of Psion's DOS-like "Command Processor" application
from the ROM of the WorkAbout (a new industrial/ corporate hand-held
computer).

CMDP was written primarily as an aid to developers working on the
WorkAbout itself.  For example, CMDP will interpret any autoexec.btf
file found on the WorkAbout on system start-up.  However, CMDP will
also run on an S3a, and it has many features that might make it
attractive to general computer-literate owners of S3a's.

CMDP accepts commands typed in by the user, or from *.BTF batch
files.  These commands allow file maintenance, machine customisation,
machine monitoring, process control, and lots more besides.

CMDP also has a menu bar, but this basically just duplicates features
available in other S3a apps (such as Time), and so is less likely to
be of interest to S3a users.

CMDP features a full command line editor to recall and edit previously
entered commands.  The display screen supports both Zoom and Wrap.

Users can type "HELP" to see a brief listing of the commands known to
CMDP.  Or type eg  "HELP SET" for more details of a given command
(such as "SET").

Full documentation on the Command Processor is available in the file
CMDPDOC.ZIP, which should be available from the same source as you
obtained this file.  CMDP.DOC (a W4W2 file) is actually a chapter
from one of Psion's SDKs.

Sorry, CMDP won't run on an S3 classic.

================================================================

In the remainder of this read-me, I'll just list a few reasons I
personally find CMDP useful, together with some observations on which
parts of CMDP.DOC do not apply for CMDP.IMG running on an S3a.

Where CMDP.DOC tells users to press Shift-Esc, S3a users simply press
the Help key.  (There's no room for a dedicated Help key on the more
restricted WorkAbout keyboard.)  Likewise, just use the standard task
keys, instead of trying to switch tasks using Psion-Tab (as works on
the WorkAbout).  Finally, although Psion-Ctrl-Del resets the
WorkAbout, it has no such efect on an S3a.  (To improve its dustproof
qualities, and for other reasons, the WorkAbout has no reset hole.)

CMDP has features to control a backlight, and a "special keyboard";
these have no effect on an S3a.  CMDP also offers a choice of serial
ports, to use with Remote Link; on an S3a, only port A will be
accepted.

CMDP.DOC describes an opening screen allowing developers to choose
between a system screen interface and the command processor
interface; clearly, this does not happen on the S3a.  (That's because
the two machines have very different "shell" programs, ie the
sys$shll.img processes.)

As for my personal notes on using CMDP on my S3a:

I often find the FILES command useful.  Thus FILES A: lists all
processes that have got files open on A:.  The output from FILES
ROM:: can also be interesting.

The SET command allows users to view and even update the environment
variables on the S3a.  Needless to say, you oughtn't to modify one of
these variables unless you are really confident you know what you're
doing!

The batch file handling in CMDP is reasonably sophisticated, as you
can see if you look at some of the examples given in CMDP.DOC.

There's a (hidden) command REASON, mainly intended for use within
Psion (that's why Help doesn't list it), giving a numerical code for
the reason for the last time (if any) the machine reset.

Note that the STOP command just sends a terminate message to apps,
rather than an "exit" message as used by the S3a System Screen.  So
you can end up losing unsaved data if you use this to stop apps.

You can even use KILL TIME to get your machine into a state you would
never normally reach (since the S3a itself has no facility to allow
you to kill Time).  This example isn't that helpful, but there are
cases when KILL LINK (or KILL SYS$NCP) may be a life saver.

Last but not least, DIR \xxx /s can be a life saver too - for when
you know you've copied a file somewhere onto a drive, but can't
remember exactly where.

================================================================

Product Development at Psion will be interested to hear of people's
experiences in using CMDP.  Any comments placed eg on the Psion
conference on CIX will be read (sooner or later).  If your comment is
WorkAbout-specific, use the psion/workabout topic; if it's just
general chatter, use the psion/chatter topic; otherwise use your own
common sense!

These notes written by: David Wood, 16th March 1995.
----------------------------------------------------