APDL Public Domain 1/APDL_PD1A.iso/emulation/cpc/!CPC_Demo/!Help

Text File | 1996-05-24 | 16.4 KB | 395 lines

 !CPC_Demo - An Amstrad CPC emulator for Acorn RISC OS machines (demo)
 =====================================================================

[For information on the full version of this emulator, !CPC, see
the end of this document.]

Copyright
---------

!CPC_Demo is Copyright (C) 1996 Mark RISON.  This copyright extends to
all the files provided in or with !CPC_Demo, except the BASIC, OS and
AMSDOS ROM images, and the FrontEnd module.  The BASIC and OS ROM images
are copyright Amstrad and Locomotive Software, and are distributed with
their kind permission.  The AMSDOS ROM image is copyright Amstrad and
Digital Research (Novell), and is distributed with their kind permission
(well, Amstrad's at least...).  The FrontEnd module is copyright Acorn,
and is distributed with their kind permission.


Conditions of use
-----------------

You may only use !CPC_Demo for your own personal and non-commercial
purposes.  You may freely distribute !CPC_Demo (including by FTP or BBS)
provided you do not modify it in any way (you must distribute it in its
entirety, including this file), and do not charge anything, either
directly or indirectly.  You may not, however, put !CPC_Demo on CD
without explicit permission.

No guarantee of any kind is made concerning operation of !CPC_Demo.  You
use !CPC_Demo at your own risk; you are advised to save all your work
before launching !CPC_Demo.


Introduction
------------

The Amstrad CPC range of computers was a hugely successful range of
8-bit computers.  There were 3 models.  The CPC464, released in 1984,
consisted of a central unit, a cassette unit and a monitor in one
package.  The CPC664 had a 3" disc drive instead of the cassette unit.
The CPC6128 had, in addition, 64K of bank-switched RAM.

All models were based around a Z80 CPU running at an effective 3.3 MHz.
There was 64K of main RAM and 32K of ROM to contain the BASIC and OS;
the disc drive models had an extra 16K ROM to hold the DOS, and the 6128
had an extra 64K of RAM.  The screen could be operated in one of three
modes: 640x200 in 2 colours, 320x200 in 4 colours, and 160x200 in 16
colours -- from a palette of 27 colours (27 greens on the green screen
models).  Sound capabilities ran to 3 channels with noise and hardware
enveloping if desired.  Two joysticks could be used with the machine.
CP/M was an option on the disc models (CP/M 2.2 on both, and CP/M+ on
the 6128).

!CPC_Demo aims to emulate a real CPC in sufficient detail to allow
programs written for the CPC to be used under RISC OS.  This entails
quite considerable translation from the CPC world to the RISC OS world;
nonetheless !CPC_Demo is roughly as fast as the real thing on machines
with an ARM3 (and faster with newer machines such as Risc PCs).


A reminder of RISC OS operations
--------------------------------

To open a RISC OS directory, double-click on it.  If it's an application
(it's got a ! at the start), press Shift as well, else the application
will be run.  To copy files from one directory to another, open both and
drag from one to the other.  To load a given file into a text editor
(e.g. !Edit) double-click on it while pressing Shift -- when you've
finished the editing pressing F3 followed by Return should save the
edited version.  To set filetypes, click on the menu button
while the pointer is above the file to be filetyped.  Finally, to access
the command line (to type * commands, setting variables, for example),
press F12 -- when you've finished press Return on its own.


File formats
------------

There are a number of formats for files suitable for use with CPC
emulators such as !CPC.

The most common file format is the disc image format (this is a file
reproducing the contents of a real CPC disc).  This can be recognised by
filenames ending in .DSK (/DSK under the standard DOS mapping).  Discs
must be used under AMSDOS (see below) -- use CAT to see what's on them,
and something like RUN"MEGADETH", or perhaps |CPM, to run them (file
extensions need not normally be specified).  Discs should be placed in
the subdirectory Discs in !CPC_Demo.  If you set a disc's filetype to
"CPC disc" (&065 at present), double-clicking on the disc will launch
!CPC_Demo with it.  Note that !CPC_Demo does not support writing to
discs.

Another file format is the snapshot format (this is a file reproducing
the state of a real CPC), recognisable by filenames ending in .SNA
(/SNA).  Snaps must be used under PseuDOS (see below).  Use
|SNAP,"MEGADETH" to launch snapshot MEGADETH.  Snaps should be placed in
the subdirectory Snaps in !CPC_Demo.  If you set a snap's filetype to
"CPC snap" (&064 at present), double-clicking on the snap will launch
!CPC_Demo with it.  |SNAPS will give a list of snapshots.

The last file format is the native AMSDOS format, consisting of one or
more files with filenames typically ending in .BAS or .BIN.  These need
to be converted to PseuDOS format using !AmsToArc (see below), and
placed in the subdirectory Tapes in !CPC_Demo.  These programs are
typically launched with RUN"MEGADETH".


Using !CPC_Demo
---------------

!CPC_Demo should mostly behave just like a real CPC!  !CPC_Demo has some
extra features, however.  You can reset the CPC not only using
Shift-Ctrl-Esc, but also by pressing Alt-Esc (you may need to try a few
times for this to work).  You can quit !CPC_Demo by pressing Alt-F12, or
by typing |QUIT (if you're using PseuDOS and not AMSDOS).

One joystick is emulated, using Insert, Home, Page Up, Page Down, Num
Lock and keypad / for left, right, up, down, main fire and secondary
fire respectively.  !CPC_Demo also supports two standard Acorn
joysticks, as found on the A3010, which will behave just like CPC
joysticks.

If a program seems to be attempting to constantly change the screen
colours, you can press Alt-P to lock out changes.  You can try this a
few times until you get a suitable palette.  If a program seems to be
attempting to constantly change the screen resolution, you can press
Alt-M to lock out changes -- again, you can keep trying until the bit
you're interested in appears right.

You can squeeze extra performance out of !CPC by running in MODE 12
rather than a higher resolution mode such as MODE 20.  This is
especially the case for games which use screen banking for smooth
animation -- symptoms are faint horizontal interleave patterns on the
screen.  In certain cases, turning palette switching off (with Alt-P)
will also speed things up.

If the machine seems to hang and neither Alt-Esc nor Alt-F12 seem to get
things back under control, you can attempt to kill the emulator off
with Alt-Delete.  This should be a solution of last resort!  If even
this does not seem to help, well ... you were advised to save all your
work before launching !CPC_Demo, weren't you?


PseuDOS and AMSDOS
------------------

AMSDOS is the original DOS provided with disc models.  It supports discs
containing about 170K of data.  Various | commands are provided by it to
handle disc files (|ERA, |REN, etc.).  To use AMSDOS the system variable
CPC$DOS should be set to AMSDOS (use *SET CPC$DOS AMSDOS from the
command line to do so).  The disc to be used can be set in CPC$Disc
(e.g. *SET CPC$Disc Megadeth); alternatively, if this variable is not
set, a list of available discs will be given, and you will be asked to
choose one.

PseuDOS is a DOS whose purpose is to allow 'tape' files to be used.
These files are held as RISC OS files in a special format.  PseuDOS
provides full access to these files. In addition, PseuDOS redefines the
CPC keyboard mappings to follow the UK RISC OS keyboard -- so if you're
using AMSDOS some keys will be wrong (in particular, " will be obtained
with Shift-2).  To use PseuDOS the system variable CPC$DOS should be set
to PseuDOS (*SET CPC$DOS PseuDOS).  !AmsToArc (as found in the Support
subdirectory in !CPC_Demo) should be used to make PseuDOS format files
-- see the help file there for more details.

CheckSnap and CheckDisc, as found in the Support subdirectory, allow you
to check whether a snap or a disc is broken in some way.  Simply
double-click to launch, and give the name of the snap or disc to be
checked when prompted.

Treat both AMSDOS and PseuDOS with care -- don't do unexpected things.
For example, if you are using floppy discs, try to keep the disc in the
drive all the time.  If you are saving under PseuDOS, make sure there's
enough free space, and that the disc isn't write-protected.


Configuring !CPC_Demo
---------------------

!CPC_Demo can be configured by adding to the file !Config in !CPC_Demo.

By changing the value for CPC$ScreenMode you can change the screen mode
!CPC_Demo uses.  Recommended values are 12 if you have a low resolution
monitor (or TV), 20 or 27 if you have a multisync or VGA monitor, or 46
if you have a CGA monitor.  A value of -1 will select the screen mode in
use when !CPC_Demo is launched.  In all cases the screen mode must be a
16-colour mode.  If you have a RiscPC, you can use a string such as
X640Y400C16 to select such a mode if it is appropriate.

CPC$Slowdown selects the amount of slowdown to be used for fast machines
(RiscPCs) to make them as slow as a real CPC.  Values of the order of
10000 should be OK.

CPC$DOS selects the DOS -- use either AMSDOS or PseuDOS.  If AMSDOS, you
can specify a disc name with CPC$Disc.

If you would like to change the place where tapes, discs or snaps are to
be found, you can alter DriveA, CPCDisc$Path and CPCSnap$Path.  Note the
latter two are path variables, so you can have more than one directory
of discs or snaps -- but remember to put a trailing dot!

The other variables should not normally need changing.


Problems
--------

!CPC_Demo, being only a demonstration version of the real thing, !CPC,
will not always get things right, and so some programs may not work
properly under it.  The symptoms can range from the mild (an inability
to count the score) to the severe (a CPC hang, which necessitates an
Alt-Esc to reset the CPC).  When in doubt, try waiting a bit, since the
program may be working away without visible effects, or may be playing a
tune (which you won't hear since !CPC_Demo does not support sound).
Also try pressing keys such as Escape, Space, Return and Fire (Num
Lock).  You can try running with palette changing disabled to see what
might be going on behind a blank screen.

You may occasionally get Internal Errors.  There are not necessarily as
bad as they sound!  You can normally attempt to ignore the error by
pressing space.  IEs such as "OPPIb" and "ICRTC" are not severe, and can
safely be skipped.  The "BANK" IE is a sign that the program is trying
to do bank switching a la CPC6128.  "DIHALT" and FDC IEs are bad news.
Any PseuDOS IEs are probably the result of bad configuration
(write-protected discs, etc.).  Note that if an IE occurs when the
palette has been set to e.g. all black, the text will not be visible;
you'll just hear a beep -- don't let this confuse you!


Limitations
-----------

Disc handling is limited (only one drive, no writing to discs).

The Z80 R register is not emulated.  This means some programs which
use R as a source of random numbers will behave rather predictably.

Z80 BCD operations are not emulated properly.  This means some programs
won't count properly, which could be either very useful or very
disastrous!

Z80 parity operations are not emulated.  This will only rarely cause
trouble.

Sound is not supported.

You cannot save snaps or make screendumps.

RAM banking (a la CPC6128) is not supported.

Extension ROMs are not supported.

Printing is not supported.


Thanks
------

Thanks are due to a large number of people.  I fear the list below may
be incomplete: not having kept a list right from the start, I had to
compile one from my records.  If you feel you've been left out, please
do not hesitate to get in touch; I'll immediately set the record straight!

Nothing should be read into the ordering of this list (it is
actually ordered by e-mail address!).

Jim Nagel, for a mention in his Computer Shopper column
Cliff Lawson, for permission to distribute Amstrad copyright material
Dave Long, for getting me to release !CPC in the first place
Frederic Elisei, pour les echanges techniques presque en continu
Kevin Thacker, for his stupendous WWW site, lots of FDC info, etc.
Nige Jones, for !CPCFront and valuable discussions
Richard Black, for info on ARM2/3 speed optimisations
Andrew Hodgkinson, for info on WimpSlot intricacies
Alan Glover, for accepting to post my propaganda to c.s.a.announce
Arnt Gulbrandsen, for ftp.nvg.unit.no
Adam Parsons, for !CPCDisk
Mike Borcherds, for info on emulation intricacies
Bernd Schmidt, for info on emulation intricacies
Mark Wooding, for info on RISC OS intricacies
Dave Allison, for info on task killers
Frank Cringle, for yaze and its brilliant Z80 exerciser
Martin Wheatley, for the games list and valuable discussions
Ian Johnson, for info on task killers
Mark Sinclair, for his MDFs for RiscPCs
Andreas Stroiczek, for competition (!CPCEmu) and discussion
Noel Llopis, for ftp.nvg.unit.no
Richard Fairhurst, for FDC and Z80 info
Richard Clayton, for permission to distribute Locomotive Software copyright material
Emmanuel Roussin, for the CPC FAQ and ftp.ibp.fr
Richard Wilson, for info on the Wimp
Susanne Albrecht, for info on Z80 block I/O ops
Sue Sound, for info on Z80 block I/O ops
Thomas Hawtin, for excellent ideas about speeding-up the emulator
Tony ?, for info on Z80 block I/O ops
Thomas Down, for info on task killers
Timothy Partridge, for info on ARM2/3 speed optimisations
Dave Walker, for permission to distribute Acorn copyright material
Robin Watts, for much marketing advice and assistance
Toby Haynes, for allowing me to test !CPC on his Risc PC
Dave Baldwin, for Z80 discussion
Ian Collier, for Z80 discussion
All the spodders on Egham Hills, for lots of technical chit-chat
Everybody who tried out !CPC while it was in its beta test phase
Everybody who showed their appreciation by contributing to the full version
And everybody else who gave me valuable feedback and encouragment!

Kaj kompreneble Marianne, kiu toleris mian duon-edzi^gon al la komputilo!

No thanks to those who promised feedback and didn't provide any.


Feedback
--------

Feedback of any nature is very welcome!  Please write to the author.


CPC resources on the Internet
-----------------------------

There is a very wide range of CPC material on the Internet.  There are
hundreds of games, utilities, documents, pictures, etc.  There's a
newsgroup devoted to Amstrad's 8-bit computers, comp.sys.amstrad.8bit.
A real treasure trove!

Your best starting point is probably to take a look at
comp.sys.amstrad.8bit, and follow some WWW URL mentioned there.  You can
also try to access the author's WWW page at

   http://www.hep.phy.cam.ac.uk:8080/rison/cpc/cpc.html

but this might not exist anymore by the time you read this (such is the
Internet!).


The full version, !CPC
----------------------

A full version of this emulator, !CPC, is available, which fixes most of
the limitations above.  It will successfully run the vast majority of
CPC programs, including many which !CPC_Demo cannot handle.  It also has
a host of features designed to make your life easier (you can change
discs within the program, mix AMSDOS and PseuDOS, try different
emulation strategies to get problem programs to work, there's full
documentation, etc.).

!CPC is shareware, with a registration fee of GBP 15.  To get !CPC,
write to the author.  If you have access to the Internet, try e-mail
first.  Failing that, send a stamped self-addressed envelope together
with a blank, formatted 800K (double density) disc to the author.
Please note that if any of these ingredients is missing, no response is
likely to be forthcoming!

Esperantistoj ^guas rabaton de kvin pundoj je la ^ci-supra prezo.
Necesas tamen iom montri onian lingvan kapablon...

If you're in or closer to Germany or France, then there are !CPC agents
there whom you might prefer to deal with instead (again, try e-mail
first and then snail-mail):

   ELISEI Frederic ([e-mail])
   Les Plaines
   F - 73600 Moutiers
   FRANCE

   Steffen HUBER ([e-mail])
   Geigeraeckerstr. 19
   D - 71336 Waiblingen
   DEUTSCHLAND

No guarantees of any kind are made concerning operation of !CPC.  It has
been tested on an 4 MB A440/1 with ARM3/25.  It will probably not work
with only 1 MB.

Also note that registering does not guarantee you any future updates,
though it is planned to make these available on the Internet, or by
sending a disc and SAE as above.


Contact details
---------------

Mark RISON
Caius College
GB - Cambridge CB2 1TA
UNITED KINGDOM

[e-mail]
[e-mail]

1996-05-24