Novation CAT

Like most other acoustically coupled modems, the CAT required the user to dial the desired number on a normal telephone, listening to the call connecting and the eventual presence of an answer tone.

There was no sort of automated operation available; even hanging up had to be done manually by returning the handset to the telephone and thereby pressing the hook button.

This was an exceptionally rare feature; modems with "full" 1200 bit/s operation were expensive devices intended to be used with minicomputers and mainframes, and typically cost thousands of dollars.

File transfer programs are written specifically for the Apple-CAT II's 202 mode, such as Catsend and the later CatFur, periodically paused and reversed transmission direction, so the receiving computer could acknowledge receipt of a stream of data, and, in the case of CatFur, could add a short chat message to the sender in the middle of the one-way file transfer.

Novation also created an 'Expansion Pack' or external breakout box that would connect to the large pin header on the top middle of the card.

This item allowed easy external access to the built-in serial port, phone line and handset connections.

The Apple-CAT II was popular with phone phreakers for its high half-duplex 1200 bit/s speed and its ability to detect various tones.

[1] Despite the Apple-CAT II's popularity, its early years were faced with incompatibility with most telecommunications programs, as its native API is considered proprietary by today's standards.

To increase compatibility without re-coding these programs, Novation released a firmware upgrade kit (an EPROM package) allowing the modem to emulate the Hayes Micromodem II, including the MMII's IN#x control codes.

Its most basic feature was that J-CAT could be placed in a mode where it would automatically pick up the phone if it was called, offering rudimentary auto-answer capability.

Instead of using in-band signalling, like the Smartmodem, the J-CAT passed the on/off-hook control, carrier detect and phone status indication to the computer through otherwise unused pins in the RS-232C connector.