MAME

The MESS system info box for the CPC6128

MESS (Multi Emulator Super System) is an emulator for vintage computers, gaming consoles, chess computers, and calculators. It is a descendant of the MAME arcade emulation project and just like MAME, the most important goal of MESS is highly accurate emulation, not speed. MESS and MAME are mainly preservation projects that aim to reproduce the behavior of the real hardware perfectly.

Currently, over 450 systems are supported, including the CPC and CPC Plus ranges and the GX4000.[1] This is probably the main reason for using MESS, that a single download is enough to emulate more or less every home computer and gaming console that ever existed in the late 1970s and 1980s—provided one can find a ROM set that works (see below). MESS does not have the depth of other emulators, but it sure has enormous breadth.

MESS runs on Windows, Mac OS X, Linux, and FreeBSD. If you also use MAME, you may want to get UME instead, which combines MESS and MAME into a single executable with a shared configuration file, ume.ini.

(info from sysinfo.dat)

Supported file types can also be shown with the "-listmedia" command line option.

You can use zipped disk images too. If there is more than one DSK image in the zip file, treat the zip file like a directory, e.g. "-flop1 disk.zip/disk0.dsk".

MESS generally supports two keyboard mode command line options: emulated (the default; based on key position) and natural (command line option "-natural"; based on the character generated by a key, e.g. pressing "z" will always generate a "z" on the emulated system, even if the keyboard positions are different).

In emulated mode, keys can also be remapped from the emulator menu: first press Scroll Lock to enable the MESS control keys, then press Tab to open the menu, and finally select Input (this system).

Just as in MAME, some MESS ROMs have parent ROMs that also need to be installed. E.g., cpc6128.zip also requires cpc464.zip to run.

ROMs often only work with a specific version of MESS. This does not seem to affect CPC ROMs, but other systems sometimes give an error message when ROM filenames or checksums do not match what MESS expected.

Various GUI front-ends for MESS exist for Windows, Linux, and OS X—see the list here: [2]

MessMenu on OS X with a CPC ROM selected. Currently, seven different CPC models are supported, including some regional variants (French and Swedish).

GLSL shader example

HLSL "1980s" shader (detail)

Like MAME, MESS can use shaders to simulate typical CRT graphics artifacts such as scanlines, colors bleeding into each other, jitter, and display curvature. This involves editing mess.ini (or ume.ini if you use UME).

Mess.ini works the same as mame.ini, so MAME tutorials can be used as a starting point. Some example configurations:

• Windows (using HLSL shaders)
  • A scripted setup with separate "1980s" and "1990s" CRT configs: [3] (huge post is halfway down the page)
  • A German shader tutorial: [4]
• Linux (using GLSL shaders): MAME tutorial [5]

• MESS will usually fail to read DSK images that use copy protection.
• Some tricks done in demos (e.g. overscan) are still slightly broken in MESS.
• Loading extension ROMs is also not supported.

JSMESS emulating a CPC 6128 in Chromium 30 on Linux

MESS has also recently been ported to JavaScript using the C/C++-to-JS transcompiler Emscripten; this port is called JSMESS. So far only a small selection of MESS machines are supported in JSMESS—the main problem is finding out which MESS modules are needed for a given architecture and creating the Makefiles accordingly, although JSMESS now includes scripts that scan for dependencies. A JSMESS fork that includes the necessary Makefiles to build the CPC 6128 version exists. (It is recommended to build JSMESS on Linux which also makes it easier to install all the dependencies for Emscripten.)

Note that cpc6128.zip also needs to contain the ROM files from cpc464.zip because unlike regular MESS, JSMESS only loads a single ROM ZIP file per machine.

Currently, sound only works in Firefox and not in Chrome/Chromium. Keymapping has not been done for most systems, although in principle you should be able create keymaps in MESS and use them with JSMESS. The joystick is mapped to Alt and the arrow keys by default.

This JSMESS CPC demo page (with the SubHunter disc in drive A) also has ZIP file download of the build.

• MAME at the English-language Wikipedia
• Official site
• MESS user's manual
• CPC ROMs for MESS (look for cpc*.zip)