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The Memotech MTX Series

Bill Brendling's version of MEMU

This page describes Bill Brendling's enhancements Andy's MEMU emulator. The contents of this page were supplied by Bill but the page has been formatted to align with the rest of the site, this includes reducing the displayed image sizes. Clicking on the images will display the original, full size, image files. Bill's original html file can be found here.


Andy Key's MEMU is an extremely effective, feature rich, and flexible emulator for the Memotech MTX series of computers, without which none of the following would have been possible. One of the consequences of MEMU's flexibility is that running the program requires supplying a number of command line switches to specify the details of the emulation required. A number of potential users find this off-putting, this was reiterated at the last Memofest meetup. There are a number of possible solutions to this issue:

  • It is possible to create a number of batch files (Windows) or command scripts (Linux) which run MEMU in a specific emulation mode.
  • Paul Daniels has produced a version of Gamebase which can be used to run many MTX games.
  • I wrote a Python based Launcher which can start MEMU in a number of standard emulation modes. However this does not support all the MEMU features.


When I first started playing with MEMU one of my main objectives was to turn a Raspberry Pi computer into a "Bare Metal" emulation of the MTX. This means no operating system and therefore no command line from which to specify the required switches. Therefore I had to provide a system for setting the configuration from within MEMU. Again I went for the option of providing a few "typical" configurations rather than supporting all of the options that MEMU can provide.

I therefore added the option of a configuration dialog as shown:


While originally developed for the "bare metal" version, the dialog can also be included in Windows or Linux versions of MEMU, which may be of interest for the reasons given above.

My version of MEMU has also acquired a few other features which have not yet been included in Andy's version:

  • The configuration dialog, as above. By default the initial configuration is read from "memu.cfg" in the same folder as the program executable. Changes made with the configuration dialog are saved back into this file. An alternative configuration file may be specified using the -config-file option on the command line. Other options may be specified on the command line as per Andy's MEMU. (Windows, Linux & Raspberry Pi)
  • Loading programs from or saving to audio (*.wav) files instead of data (*.mtx) files. This provides one way of developing a program on MEMU and then transferring it to a real MTX (or vice-versa). (Windows, Linux & Raspberry Pi)
  • Emulation of the CFX-II addon, including the Propeller VGA display. (Windows, Linux & Raspberry Pi)
  • Running Fuzix (a Unix/Linux clone). This relies upon the CFX-II emulation. (Windows, Linux & Raspberry Pi)
  • Enhanced keyboard remapping to improve the usability of MEMU with modern keyboards. This follows the approach used for the PC keyboard interface, and allows the keyboard mapping to be changed dynamically, using the <Scroll Lock> and <Num Lock> keys. (Windows, Linux & Raspberry Pi)
  • Using a real serial port to emulate the MTX serial port. This allows multiple machines running MEMU to be connected in a NODE ring. This has been tested with a Raspberry Pi connected to an x86 PC. It should be possible to similarly connect MEMU to a real MTX, but this has not been tested. (Linux only, including Raspbian)
  • Use of Raspberry Pi GPIO to connect MEMU to real hardware, including keyboard, joystick and printer. (Raspberry Pi including bare metal)
  • Use of Raspberry Pi GPU to accelerate MEMU display. (Raspbian only)

Conversely, my version can be a year (or more) behind the latest features added to Andy's version.

For convenience I have created a number of distributions:

Distributions (Downloads)

Microsoft Windows Runtime

This contains two 32-bit versions of MEMU:

This is the classic command line version of MEMU.
This is the version of MEMU with configuration dialog.

To install, simply unzip the distribution into a suitable location, perhaps "Program Files (x86)". It may be worth creating a desktop shortcut, pointing to "memu-cfg.exe", with the working folder set to the folder containing the program.

Linux (x86) Runtime

This distribution contains four versions of MEMU. Two are for use with X-Window displays:

This is the classic command line version of MEMU.
This is the version of MEMU with configuration dialog.

The other two are for use from the console, without X-Window, and display full screen. Use <Ctrl> plus the function keys to switch between VDP display and 80-column display:

This is the command line version of MEMU using full-screen frame buffer.
This is the configuration dialog version of MEMU using full-screen frame buffer.

To install, unzip the file into s suitable location. Optionally copy the contents of the "memu" folder into a location on the path, such as "/usr/local/bin".


Raspbian Runtime

This distribution contains the same four executables as the Linux distribution, but compiled for 32-bit ARM. It also contains a fifth executable:

This version of MEMU is intended for use from the console, without X-Window. It displays full-screen, using the Raspberry Pi GPU. It can also use the GPIO to interface to real hardware.

Bare Metal Runtime

This distribution contains the bare metal version of MEMU (with configuration dialog), compiled for different versions of the Raspberry Pi. At present the following are NOT supported:

  • Running on a Raspberry Pi model 4B
  • Serial port (DART) emulation
  • GPU acceleration

Source Distribution

This distribution contains the source code for all the above versions. There are build scripts in the top level folder for building all versions. The building has to be performed on the appropriate hardware (Windows, x86 Linux or Raspberry Pi) for the distribution being built. Cross-compilation is not currently supported.

To save space, none of the ROMs, disk or tape images are in this distribution, you need at least one runtime distribution. The runtime should be installed in a folder "memu" under the top level folder.

Configuration Dialog Versions

When first started, the configuration dialog versions of MEMU start in whichever emulation mode was last saved in the configuration file. To display the configuration dialog, use one of the following keys:

  • <SysReq> key
  • Left <Windows> key
  • Right <Windows> key
  • <F11> key

Different operating systems trap different key strokes for their own use, so try each of these to find one that works. Once in the dialog, use the arrow keys to navigate, and either the space bar or <Enter> key to select an item. To exit the dialog and return to the emulation select one of the options from the bottom line of the dialog. Note that "Exit" is exit the program not exit the dialog.

While the emulation is running, the following key strokes are also processed:

  • Pressing both the <Alt> keys and then releasing them reboots the emulation. The reboot actually happens when the first of the keys is released. In CFX emulation, selecting a mode requires holding another key down while rebooting. Depending upon the operating system being used, try either of the following:
    • Press and hold one <Alt> key. Press and hold the required letter key. Press and release the second <Alt> key. Release the first <Alt> key. Release the letter key after a few seconds.
    • Press and hold both <Alt> keys. Press and hold the required letter key. Release the <Alt> keys. Release the letter key after a few seconds.
  • If keyboard mapping is enabled, then the following keys influence the mapping applied:
    • If <Scroll Lock> is off, then the keys exactly as on the MTX are emulated. This will work with all MTX software, but means that for some symbols you have to press a differently labeled key on the PC keyboard. See here for details. If <Scroll Lock> is on, then keys which do not exist on the real MTX are emulated to produce characters matching the symbols on the PC keyboard. The MTX ROM and CP/M are patched to recognise these additional keys, but they will not work with any software which has its own keyboard driver.
    • If <Num Lock> is off, to assist game play, the PC numeric keypad is mapped to the MTX keypad by key position. However this means that the keypad keys do not produce the numbers shown on the keys. If <Num Lock> is on, then the mapping is changed so that the numeric keypad produces the expected numbers.
    On some operating systems, it is not possible to ensure that the keyboard LEDs match the lock state as seen by MEMU. If keys are not producing the expected result it is therefore worth changing the lock states.

Within the configuration dialog, if "Audio Tapes" is turned off ("No") then only binary (*.mtx) tape files can be selected. In this mode, tape files will load very quickly. If "Audio Tapes" is turned on ("Yes"), then either binary (*.mtx) or audio (*.wav) tape files may be selected. However all files will be slow to load (realistic speed), and you will hear an approximation of the tape loading sounds. Binary files are effectivly converted back to audio in order to load them. Audio files in other formats such as *.mp3 must be converted to *.wav before they can be used.

The supplied disk images are in a number of sizes:

  • Files with an extension of "*.mfloppy" or "*.mfloppy-07" are 640KB type 07 floppy disk images which may be used as B: or C: disks in SDX or CP/M emulations.
  • Files with an extension of "*.img" are 8MB CP/M partitions. They may be used as either Compact Flash partitions (types 18 to 1F) or Silicon Disks (type 4F).
  • "ht.bin" is a large data image used by Hextrain. It is not readily accessible to other MTX software.
  • "" is an image of a multi-partition drive, for booting Fuzix.

Typical configuration for SDX emulation


The image opposite shows a typical configuration for SDX emulation, with a tape file ready for loading with the command LOAD "", and a disk of games available for USER LOAD "game".

Any user programs can be saved with USER SAVE "name"

Typical configuration for CP/M emulation


 A typical configuration for CP/M emulation, with two floppy disks, is shown opposite.



Typical configuration for CFX-II emulation 1

For the CFX-II it is necessary to open a sub-dialog to select the files to form partitions on the emulated Compact Flash cards.



Typical configuration for CFX-II emulation 2

To open this dialog, select the Compact Flash card on the main dialog, and then use <Space> or <Enter> to open the sub-dialog.



Hextrain configuration

Hextrain is Andy Key's incredible MTX game with 3D graphics.

To run this, set the configuration as shown and restart.

Once CP/M has started type the command "hextrain" (renamed from "htsi"), and then switch to the VDP window or display

Fuzix configuration 1

Fuzix is a Unix like operating system for Z80 machines.

It has been ported to the MTX with CFX-II storage add-on, and can be run in MEMU. To run it, set the configuration as shown:


Fuzix configuration 2

Restart, then once the CFX-2 startup page is showing, reboot using the two <Alt> keys with the "C" key down, as if rebooting to CP/M.
Fuzix configuration 3

When prompted for "bootdev:", enter "hda1" (without the quotes). Enter the date and time when requested. Finally login as "root". When finished using Fuzix, enter the command "shutdown" to cleanly unmount the emulated drives and halt the system. Otherwise a lengthy check of drive integrity will be required next time Fuzix is started.

Configuration Options

Group Option Description
Hardware MTX500 Memotech MTX500 With 32k byte of RAM
  MTX512 Memotech MTX500 With 64k byte of RAM
  SDX Memotech with 576k bytes of RAM and two type 07 disks
  CPM MONO 576k bytes of RAM, two type 07 drives, CP/M mono monitor
  CPM COLR 576k bytes of RAM, two type 07 drives, CP/M colour monitor
  CFX-II 576k bytes of RAM, two CF cards, Propeller VGA Display
Keyboard Normal Keyboard Keys match MTX keyboard - Not always PC key symbols
  Remapped Keyboard Multiple keyboard modes - More closely match PC key symbols

Further details of the keyboard remapping function is described on Andy's MEMU keyboard page.

Sound No Sound Disabled
  Yes Sound Enabled
Audio Tapes No ".mtx" files Only
  Yes ".mtx" and ".wav" Files
Tape Select "tape" to load Use Cursor Keys to select the required tape (.mtx) file
Save Tape Select save "tape" Use Cursor Keys to select the required tape (.mtx) file
Huge SiDiscs No [For CFX] SiDiscs limited to 8MB
  Yes [For CFX] Huge SiDiscs for HexTrain
Save Si Drives No [For CFX] SiDiscs contents lost on exit
  Yes [For CFX] SiDiscs contents saved (slow for huge discs)
CF Card 0 Select "disk" to load [For CFX] Edit CF Partitions
CF Card 1 Select "disk" to load [For CFX] Edit CF Partitions
Drive B: Select "disk" to load [SDX/CPM] Select the required disk (.mfloppy) file
Drive C: Select "disk" to load [SDX/CPM] Select the required disk (.mfloppy) file
Drive F: Select "disk" to load [CPM/CFX] Select the required disk image file
Drive G: Select "disk" to load [CPM/CFX] Select the required disk image file
Drive H: Select "disk" to load [CPM/CFX] Select the required disk image file
Drive I: Select "disk" to load [CPM/CFX] Select the required disk image file
Action Apply Change disk and/or tape and continue MEMU
  Cancel Continue MEMU with no changes
  Restart Make changes and restart MEMU
  Exit Exit MEMU and shutdown the Raspberry Pi

Command Line Versions

Most of the command line usage is as per Andy Key's Documentation which is repeated here.

Switch Description
-iobyte iobyte specify IOBYTE (initially 0x00)
-subpage subpage set ROM subpage (initially 0)
-addr addr set the address (initially 0x0000)
-mem file load file at address
-mem-blocks n number of 16KB memory blocks (default 4)
-mem-mtx500 equivelent to -mem-blocks 2
-n-subpages rom n set number of subpages
-romX file load ROM X from file
-rompairX file load ROM X and X+1 from file
-vid-win emulate VDP and TV using a graphical window
-vid-win-big,-v make window twice as large (realistic size)
-vid-win-hw-palette use an alternate palette
-vid-ntsc refresh at 60Hz (instead of 50Hz)
-snd-portaudio,-s emulate sound chip using portaudio
-snd-latency value instruct portaudio to use a given latency
-mon-win emulate 80 column card using a graphical window
-mon-win-big,-mw make window twice as high (realistic aspect ratio)
-mon-win-mono green screen monochrome
-mon-th,-mt emulate 80 column card using full screen text mode
-mon-console,-mc emulate 80 column card using console only
-mon-console-nokey keyboard status shows no keys pressed
-mon-no-ignore-init don't ignore writes to non-emulated registers
-kbd-remap remaps MTX keyboard (despite shift state)
-kbd-country n sets the country code switches to n (default 0)
-kbd-type string auto type keys in this string
-kbd-type-file fn auto type keys in this file
-joy,-j enable joystick support
-joy-buttons string define left,right,up,down and fire buttons
-joy-central n percentage off-centre to press direction
-serial1-in fn serial 1 input from file/pipe
-serial1-out fn serial 1 output to file/pipe
-serial2-in fn serial 2 input from file/pipe
-serial2-out fn serial 2 output to file/pipe
-sdx-tracks n specify tracks of first drive (default 80)
-sdx-mfloppy file specify .mfloppy file in SDX first drive
-sdx-tracks2 n specify tracks of second drive (default 80)
-sdx-mfloppy2 file specify .mfloppy file in SDX second drive
-sidisc-huge enable Silicon Disc huge mode
-sidisc-no-save don't save Silicon Disc content on termination
-sidisc-file n file specify Silicon Disc content for a drive
-prn-file file specify file to receive printer output
-tape-dir path .mtx files are in this directory
-tape-overwrite SAVE can overwrite an existing file
-tape-disable don't patch INOUT to LOAD/SAVE/VERIFY .mtx files
-tap-file fn specify ZX tape file (default memu.tap)
-sna-file fn specify ZX snapshot file (default memu.sna)
-cpm emulate CP/M BDOS
-cpm-drive-a path where CP/M BDOS finds A: files (default: .)
-cpm-invert-case invert between CP/M and host filenames
-cpm-tail tail construct CP/M command tail
-cpm-open-hack don't insist on EX,S1,S2,RC being 0
-sdx SDX support in ROM 5 (or -sdx3 for ROM 3)
-fdxb FDXB CP/M support
-speed hz set CPU speed (default is 4000000, ie: 4MHz)
-fast don't limit speed, run as fast as possible tail ... -cpm -iobyte 0x80 -addr 0x0100 -mem -iobyte 0x00 -addr 0xAAAA (from header)
file.mtx subsequent LOAD/SAVE/VERIFY "" will use this file

The additional options for my version are:

Switch Description
-vga emulate Propeller VGA display
-serial1-dev dev  serial 1 in/out from device
 -serial2-dev dev serial 2 in/out from device
-cfx2 rom_file enable CFX-II emulation and specify ROM image file
-cf-image c:p file specify data image for partition (p) on card (c)
-cassette-in hardware emulation - MTX or WAV file to load
-cassette-out hardware emulation - MTX or WAV file to save
-mon-win-title set title for 80 column window
-mon-win-display set display to use for 80 column window
-vid-win-title set title for VDP window
-vid-win-display  set display to use for VDP window
 -help displays list of options and exits

The configuration dialog version also uses the same switches, storing them in the configuration file, but they may also be given on the command line. There are a few additional switches listed below to support the operation of the dialog.

Switch Description
-config-file file read configuration options from file
-no-ignore-faults turn off permissive options enabled by -config-file
-rom-enable rom_bits bit flags to enable (1) or disable (0) a rom
-no-cfx2 rom_file disable CFX-II emulation but specify ROM image file
-mon-size sets 80 col size (but does not enable it)
-disk-dir directory containing disk images
-tape-dir directory containing tape files

And finally, two further switches specific to the Raspberry Pi specific versions:

Switch Description
-hw-config file specifies the GPIO interface to MEMU, documented here
-gpu-mode mode controls the use of the GPU for screen upscaling (memu-pi only):
  • mode = 1: Upscaling by ARM processor
  • mode = 2: Upscaling by GPU with interpolation
  • mode = 3: Upscaling by GPU without interpolation (default)

Revision History
2019-12-26 Added Visual Debugger Function - see documentation page
Bug fix on CTC emulation in timer mode with a zero constant
2019-11-17 First Release

Download Build Date MEMU Base Description
2019-12-26 2019-10-12 Source Code
2019-12-26 2019-10-12 Bare Metal Runtime (Raspberry Pi)
2019-12-26 2019-10-12 Raspbian Runtime (Raspberry Pi)
2019-12-26 2019-10-12 x86 Linux Runtime (32 Bit)
2019-12-26 2019-10-12 Microsoft Windows Runtime (32 Bit)
2019-11-17 2019-10-12 Source Code
2019-11-17 2019-10-12 Bare Metal Runtime (Raspberry Pi)
2019-11-17 2019-10-12 Raspbian Runtime (Raspberry Pi)
2019-11-17 2019-10-12 x86 Linux Runtime (32 Bit)
2019-11-17 2019-10-12 Microsoft Windows Runtime (32 Bit)
2019-11-17 n/a Memu-Pi GPIO Configuration



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