Thomson TO9 Emulation in MESS

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Thomson TO9 (French, Sep 1985)

Driver name: to9

Much improved successor of the TO7/70, destined for semi-professional usage. Note that it is older than the TO8.




Startup Menu

From the startup menu, press SHIFT+1 and SHIFT+2 to access the internal software (text-processor and database), SHIFT+3 to get the BASIC 128, SHIFT+4 for the old BASIC 1.0, SHIFT+5 to change the color palette, and SHIFT+6 to access the graphical DOS.


An optional cartridge can be inserted with the -cart option. It can be started from the startup menu by pressing SHIFT+0.

The TO9 can run TO7 and TO7/70 cartridges, but not MO5 ones.


They have the same format as the TO7 and TO7/70 ones, and MESS recognizes the same image types (.wav and .k7).

We recall that cassettes are loaded with one of the two following BASIC commands: RUN"" (for BASIC files), or LOADM"",,R (for binary files). Please see the to7 driver for more information.

Thanks to the backward compatibility, you should be able to run most TO7 and TO7/70 software, provided that you load them from the old BASIC 1.0 and not the BASIC 128.

Note that to use cassettes with the BASIC 128, you must use the commands RUN"CASS:" and LOADM"CASS:",,R respectively because the cassette device is no longer the default one.


The TO9 has an internal 3"1/2 drive, and allows two more external 3"1/2 drives to be connected. They are named -flop0, -flop2, -flop3. In theory, drive number 1 (-flop1) does not exist: it corresponds to the hypothetical second side of the one-sided internal drive. But MESS emulates -flop1 anyway...

Using the built-in internal controller, only 3"1/2 floppies can be reliably used. 2"8 and 5"1/4 floppies might work partially. You can also choose to use an external floppy controller instead of the built-in one: select the controller using MESS's in-game menu and reset the emulated computer. More information is available on the to7 driver page, as the external controllers are the same. Note, however, that external controllers are not fully reliable on the TO9, due to addresses conflicts.

Floppies are TO7, TO7/70 and MO5 compatible. The same .fd and .sap image formats are recognized.

Floppies can be used directly form the BASIC 128 (SHIFT+3). Then use the commands DIR, LOAD, SAVE, RUN, DSKINI as usual (see the to7 driver). Most games are bootable. Simply insert the floppy in drive 0 (-flop0) and press D in the startup menu.

Using floppies with the old BASIC 1.0 is also possible, but more complex. You must first insert a BASIC DOS boot disk in drive 0, and then start the BASIC (SHIFT+4) in the startup menu.

The graphical DOS (SHIFT+6, then select a drive number) allows formatting and copying floppies, but not running them. Note that the 5-th drive, numbered 4, does not correspond to a real floppy, but to a 64 KB RAM disk.


The keyboard is AZERTY, with a keypad, a CAPS-LOCK key and function keys.

  F1/F6   F2/F7   F3/F8   F4/F9   F5/F10

  #@   *1  é2  "3  '4  (5  _6  è7  !8  ç9  à0  )°  -\  =+  ACC       UP           7   8   9

 STOP    A   Z   E   R   T   Y   U   I   O   P  ^"  $&    ENTER  LEFT  RIGHT      4   5   6

 CTRL  [{ Q   S   D   F   G   H   J   K   L   M   ù%  ]}            DOWN          1   2   3

CAPS SHIFT W   X   C   V   B   N   ,?  ;.  :/  ><  SHIFT   HOME   INS  DEL        0   .  ENT


As for modern AZERTY keyboards, SHIFT must be held down to enter digits.


A TO8-compatible mouse (connected to the second generation game port) is emulated. The TO9-specific mouse (connected to the keyboard) is not working yet.


Most of the time, MESS uses a low-resolution 320x200 screen image. It allows emulating most modes (160x200 and 320x200). To represent faithfully the 640x200 mode, MESS automatically switches to a slower, high-resolution mode.

The choice of low- or high-resolution emulation used to be user-defined. You can still set it manually in MESS's in-game menu. It is now set by default to the new auto option that switches to high resolution only when required.

640x200 video mode low-resolution emulation 640x200 video mode in hi-resolution emulation

Known Issues

History and Trivia

The TO9 was a high-end product destined to a semi-professional usage. It included lots of RAM, software in ROM, a 3"1/2 floppy drive. It had a desktop look with a separate keyboard and an optional mouse. It was a TO family computer, backward compatible with the TO7 and TO7/70 (but not the MO5). It was the first Thomson computer based on the new video gate-array that increased greatly the video capabilities. Also, it was the first Thomson to have a dedicated keyboard chip (former ones relied on CPU pooling).

Alas it had many problems. The text-processor and database management software included in ROM were quite buggy. Even the BASIC 128 was not able to access the full power of the TO9 (in particular, the 64 KB RAM extension could only be used as a virtual RAM disk, not as a main memory). The integrated floppy drive was one-sided. It was considered somewhat immature and quickly replaced with the improved TO9+.


This MESS driver was written by Antoine Miné.

Return to the 8-bit Thomson MESS driver page.