A-CPC
A-CPC was written in the UK by
Computer Science student Kevin Thacker, on a Amiga 500 with Workbench 2,
Devpac and twin floppy drives. It does not have a built in monitor,
but can emulate the 'Multiface 2', a CPC device similar to Action Replay,
if you've got the right ROM file. The demo is usable but crippled:
it can't SAVE, use joysticks or emulate the Multiface.
The full version allows direct access to real CPC disks, and instructions
for anyone brave enough to connect a three inch drive to their Amiga. Even
if you manage this, you're unlikely to be able to read copy-protected disks,
but disks in normal CPC format will be accessible from the Amiga Shell.
A-CPC will run on a 68000 Amiga,
but very slowly - it works best on a 68030 and I couldn't get it to run at
all on a 68060. It emulates all the original Amstrad models from 464 to 6128,
and the registered version - available for £10 - supports CPC+ features as well.
A-CPC needs at least a Meg of RAM
and comes in versions for old and new processors. It's system friendly, with
pull-down menus, and can read disk images and snapshots from the PC-compatible
CPCEMU and CPE emulators, which are widely available on the Web and FTP sites.
AmiCPC
AmiCPC also expects a 68030,
although it will run on 68020 systems. I tested version 0.33, which is
freeware. Like A-CPC it needs a
15 KHz PAL monitor and objects to AGA mode promotion. It is faster than its
rivals, but you need a 68030 or better to run most programs at full speed.
The 'turbo' version requires 2 Megs of fast memory, and manages about 20
per cent of real Amstrad speed on a 14 MHz Amiga, or 660 KHz in Z80 terms.
It's more than twice the speed of a real CPC, on a 68060.
Sound emulation is limited to simple tones. Most of the documentation is in
French, with about four pages in English. It's a nice freeware emulator and
well worth looking at, especially if you understand French. It's coded in
approved style with menus and tooltypes, multi-tasks well and doesn't tie
up the Amiga, even if you leave it running in the background.
CPE
CPE is a relatively limited emulator, based on an early version of an
eponymous emulator for PC clones, and an old Amiga emulator for obsolete
CP/M business machines. The assembler source code supplied needs changes
for processors after the 68000. I spent a while tweaking it, with some
success, but could not get the keyboard working properly.
Disk support is rudimentary and there's no emulation of CPC sound effects.
CPE does include a reasonable Z80 monitor. You're probably better off with
one of the other CPC emulators, although real enthusiasts might find the
source code interesting.
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EmuCPC
EmuCPC was also written in France,
once a key territory for Amstrad sales and the home of many CPC enthusiasts.
Version 0.4B arrived on Aminet at the beginning of this year, and works quite
well, although rather slowly. It requires Workbench 3.0 and at least a 68020.
It emulates the 64K Amstrad 664 with one disk drive, and can work with disk
images as well as A-CPC CPCEMU and CPE memory snapshot files.
EmuCPU multi-tasks but there's not much CPU time left, unless you call up
one of its ReqTools requesters to pause the ferocious CPU drain of the Z80
emulator. It's noticeably slower than its rivals in 16 colour MODE 0 on a
68060, which suggests that it may be relying on instructions which the
68060 has to trap and emulate.
EmuCPC is freeware with just two
A4 pages of documentation, but some useful example files. It supports add-on
Amstrad 'ROM' files, and comes with Amiga shell utilities to format,
read and write 180K 'disk' files.
There are no menus. Function keys, listed when you the start the program,
change screen mode, reset, swap disks and save and load snapshots. The
original CPC keymap is emulated, with simple help text available on F7, as
the Amiga keytops and CPC characters do not correspond. This is a common
problem with all the CPC emulators - it would have been nice to have had an
option to use the Amiga rather than the Amstrad keymap.
New version
EmuCPC is being actively developed
and a new version, 0.7, arrived on Aminet as this article was prepared.
This one can emulate the 6128 model and programs which change the display
resolution part-way down the screen. Four versions are now included, varying
in speed, RAM capacity and accuracy of graphics emulation.
Perhaps the most significant advance is provision for fast parallel
transfers from a real CPC to your Amiga. EmuCPC 0.7
comes with instructions showing how to link the parallel ports of the
computers with nine wires, and software to manage both ends of the link,
transferring the contents of a three inch disk into an Amiga disk image file.
You need another custom cable to get the transfer program from Amiga to the
CPC. This time EmuCPC uses the
cassette interface, generating tones through one of the Amiga's sound channels
which the CPC interprets as a program. This is trickier, as it can be messed
up by signal levels and processor speed - you might end up having to retype
the CPC part of the transfer program, which is about 5K of BASIC.
In the absence of any direct way of loading CPC cassettes onto the Amiga,
this is an ingenious and important utility which marks out EmuCPC from the
rest. The new uses icon tool-types for configuration, making it yet more
Amiga-friendly.
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