Yup - How does the Silver Surfer work? I just happen to have one laying around here;)
You plug it into the clockport on the Retro Replay and you close the flash jumper on the Retro Replay. Turn on the machine and load a program that supports it. I use Novaterm all the time and get at best stable 57600 BAUD, in 64 mode (Novaterm uses 64 mode on the 128, but access the VDC 80 col chip).
and does it really work somewhat like the old Action Replay for freezing memory resident programs? - both 64 and 128.
I don't think I ever used an Action Replay, but I've used the freezer on RR all the time. Works great, but 64 mode only.
And finally, where did you get yours from. The German sight I found that sells it what a fortune for shipping.
My own company was a reseller, but I havn't been selling for some time now :-( You could always buy directly from Individual Computers. Or, if you are going to wait a while, I may actually start selling C= 8bit stuff again in a month or so.