As someone previously posted, yes the Imsai 8080 is a real system. The floppy drive unit is an external box the same size (and much heavier as I recently found out) than the computer. Due to the weight they were sometimes installed in a rack beside the desk,although they could be stacked like the movie or a hobbiest would likely do. The modems then were usually a rubber speaker and microphone that you would put the receiver of your telephone onto and it would interpret the modulation of sound to a byte and make the tones back to talk.
Yeah, old stuff, sorta before my time (by the time I got online we had 2400baud modems which seemed great except on large listings of data) and I never knew anyone that had the receiver type modem. I have one or two for some systems.. was thinking about modding one to work on a cell phone just for shiggles.