1964 Antique MODEM Live Demo

[Gordon JC Pearce]

On Mon, 2009-06-01 at 15:32 -0400, Mark G. Thomas wrote:

> 
> At first I thought he was just oversimplifying, but then it became
> clear he didn't understand it, when he started talking about wrong 
> frequencies, and didn't get that the tone change when he connected
> the laptop was just the change from space to mark (or vice-versa?).
> 

Okay, let's try again.  I have a circa-70s 300-baud modem, that will
generate incorrect tones when it's plugged into a USB-to-serial
converter, but not when it's plugged into a real serial port.

Why might this happen?

Gordon