These are 4 buttons on the right side of a file transfer window in AIM. Their purpose is to regulate the rate of the transfer, with respect to the maximum transfer rate of the connection. They are labeled "fast", "medium", "slow", and "paused". Based on empirical evidence with a variety of connections, I have reached these conclusions:
- Fast
This will send the file(s) at the maximum sustainable rate for both parties.
- Medium
This will send the file(s) at approximately half the speed Fast sends it/them at.
- Slow
This will send the file(s) at approximately half the speed of Medium (or one fourth the speed of Fast).
- Paused
This pauses the transmission without terminating it. Useful if one of the parties needs full bandwidth momentarily for something.
That said, AIM has a few quirks related to its file transfer capabilities:
- AIM displays the transfer rate incorrectly when it is above 1MB/s. If I had to guess, I'd say it calculates the speed modulo 1024KB/s.
Update: fixed around version 5.2. It now correctly displays the speeds achieved over 10/100 ethernet. I haven't had a chance to test it on gigabit yet.
- AIM dies horribly when a file >2GB is sent. The transfer never starts, and AIM on the sender's machine crashes and refuses to restart until after a reboot (at least on my systems).
Update: fixed around version 5.2 as well. The limit is now upwards of 10GB.
- The radio buttons outlined above have little or no effect if one or both parties is using dialup or another similarly slow internet connection.
Tests conducted over the past year or so using aim clients 4.5 through current (5.0.2938)