The entire documentation can still be found herehttp://www.bgmicro.com/pdf/acs1394.pdf.

These kind of units do crop up on the surplus market once in a while but sell out fast. I have one here that was just $20 but that does have a binary interface only. (Easy to use all the same.) Came with a nice patch antena too that was worth more than the $20 alone.

Cheers,

Rex.