Not CP/M admittedly, but small contemporary
Burroughs machines certainly used cassettes, both
for program and data storage. I wrote several
fairly complex diskless accounting systems using
four cassette drives, one or two card readers and
a line printer (in addition to the console
printer).
Why not; not much different conceptually after all
 from early systems using open-reel mag tape, or
even punch(ed) cards.
m
----- Original Message -----
From: "Chuck Guzis" <cclist at sydex.com>
To: "General Discussion: On-Topic and Off-Topic
Posts" <cctalk at classiccmp.org>
Sent: Monday, September 21, 2015 1:42 AM
Subject: Re: Multi-platform distribution format
(Was: Backups [was
  On 09/20/2015 09:55 PM, tony duell wrote:
 Gee, I thought we were talking about CP/M
 here.  How many CP/M
 systems used cassette for storage.  Better
 yet, how many
 commerical/industrial CP/M systems used
 cassettes for program
 storage. 
 Epson PX8? 
 
 That's a commercial or industrial system?  Did
 it run an EDM setup, turret lathe  or
 vacuforming machine?  Anyone keep their AR, AP,
 GL, payroll and inventory on one?   I doubt that
 one could run a PBX.
 I never looked at the Geneva or QX-10 as much
 more than word processing setups.
 --Chuck