PerCom Data Co. was started by Harold  Mauch in 1976 to manufacture peripherals for early home computers.  Byte magazine sponsored a conference in Kansas City to define a standard for storing data on audio cassettes. Mauch attend that conference and wrote an article for Byte showing an example design. The CI-810 Cassette Interface was PerCom's first product. It connected to a parallel port and was followed by the CIS-30+ that connect to a serial port. These interfaces were typically used with Motorola 6800 based computers such as the SWTPC6800.
The "Kansas City" standard recorded binary data using two tones (1200 Hz and 2400 Hz) at a 300 baud data rate. At 30 bytes per second it took over 4 minutes to load an 8K file.
PerCom Data Co, Garland, Texas
1977-05
Scanned from the May 1977 <i>Byte</i> magazine (page 153) by Michael Holley <a href="//commons.wikimedia.org/wiki/User:Swtpc6800" title="User:Swtpc6800">Swtpc6800</a>