PulkoMandy (./95) :
D'abord, serait-il possible que quelqu'un essaie un de mes adaptateurs sur un ST, avec une souris usb optique, du genre avec des dels qui clignotent de toutes les couleurs dedans, c'est pour voir si le ST peut fournir assez de courant sur le port souris pour alimenter un engin comme ça.

Tous les différents adaptateurs PS/2 pour Atari que je connais n'utilisent que le 5V fourni directement par le port souris, et à ma connaissance personne ne s'est plaint d'avoir des problèmes d'alimentation, même avec des souris optiques.

Y'a aussi ça comme information dans la FAQ de PeST (un adaptateur souris "concurrent") :

Q. Is it safe to use optical mice which draw 125mA, I'm using a TT. Thanks, JH
A. We always look forward to your questions JH :-). We would hazard a guess that 125mA is pushing the limits through an external MSTE/TT keyboard although in all honesty we're not totally sure. Where the original STFM cases are concerned where the keyboard is internal this definitely isn't a problem as PeST was developed with one of these 125mA optical mice in question and has been powered for weeks on end. System wise the TT keyboards are identical in operation to the internal keyboards; same chips, same specification etc. etc. The only thing which would throw a spanner into the works would be the length of the coiled cable, being about 2 metres in length if uncoiled. The PeST does have it's own smoothing capacitor to catch any irratic +5v supply, but at 2 metres that makes us wonder if further smoothing would be required. Where the TT is concerned we're now tempted to suggest with the standard PeST (0.1uF smoothing cap) that a mouse that requires less than 100mA and one which doesn't use heavy sudden draining red leds to light the desk up be used. If anyone is reading this with the intention of using PeST with a TT please let us know when purchasing. The original ST mouse/joystick ports were used at times to supply floppy disk drives, 500mA+, so we know the power is there. It wasn't highly recommended at the time however and was questioned, 1980's, and it's not necessarily recommended now. 100mA is not a huge drain, 500mA is. And since our machines are now 15 years+ old the electrolytic capacitors in the power supplies could ideally be replaced to maintain optimum function, we've all seen how the screen can dim/flicker slightly when the floppy drive is being accessed, that's a struggling power supply That 125mA figure will also be maximum power drain not constant. It is an educated guess. The final recommendation following this short debate is to minimise on mA usage with external keyboards where the +5v supply may be dirty. The other recommendation is to replace the large electrolytic capacitors in your power supply, this is plain good practice.