Well, looking more closely at these texts, you need to read them from right to left (as it's the case with Arabic language) and we have : RETURN - GAMES - MAZES - HOPPER - TIME CURB - BREAK IN - HYPE - ALPINE SKI - SKOOTER - MOON RIDER - TT RACER - SNAKE IT
So, no any special modem rom, but a rom with a menu to the built-in games ... but how to access to this menu ? And where are these games ?
It corresponds to this picture :
Probably the dump of the rom in slot 0-1 is not complete, we should have a megarom with these games, but here SaveROM with the good parameters (Ascii8 megarom ?) needs to be used and I guess it's better to have an external diskdrive
Correction : I had "switched" 2 roms ...
Rom in slot 0-1 is the Arabic MSX1 rom, uncomplete dumped rom in slot 2-0 is megarom with games
If I select ASCII8 or ASCII16 as mapper for the rom in slot 2-0, there are 2 extra options in the main menu and I can access to the game menu and to another menu !
So, the only remaining problem is the complete dumping of this megarom 
Thank you very much for your efforts
Today I was talking with Bifi on this subject ... he said I need to use Saverom....and i need a external FDD or CF IDE for that... 
I talked to sunriseformsx.nl about the CF IDE...the answer was "No more and Never again !"
Can I modify the GETROM.BIN source...to make it read from the MegaRom ?
Nice Job...but must get the megarom...I think i will get a MSX FDD ...any suggestions where to get one ?
Just a thought - wouldn't the Arabic ROM be something along the lines of Kanji / JIS ROM for Japanese systems (charset graphic data), therefore standard and likely the same as in other Arabic MSX machines? (mass-produced mask ROM etc). Might be a megaROM as well.
Comparing the BIOS / Basic ROM with that of other MSX1 machines, should provide clues about how it's controlled. The difficulty here is probably more how to get that data onto tape / floppy / flash card...
The ROM(s) that hold the NES games might not even be accessible within the MSX system, but more a 'set game #, toggle a hardware control to make the NES part take over' kind of thing. (and personally I couldn't care less about the NES games in there 
).