Novation CAT

Novation was an early modem manufacturer whose CAT series were popular in the early home computer market in the late 1970s and early 1980s, notably on the Apple II. The Hayes Smartmodem 300, introduced in 1981, helped kill off Novation and many other early modem companies over the next few years.

Novation's first CAT was an external 300 bit/s Bell 103-standard modem that connected to the phone lines using an acoustic coupler. Like most other acoustically coupled modems, the CAT required the user to dial the desired number on a normal telephone, and then press the handset into rubber cups on the modem if a carrier could be heard. This was only possible because telephones were generally available only from Western Electric, all of a standardized size and layout. 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.

Novation also introduced an internal direct-connect modem, the Apple-CAT II, which plugged into an expansion slot in an Apple II computer. Due to the internal connection, the APPLE-CAT II was able to feature a full range of dialing commands, and could report a wide range of call progress tones (BUSY, REORDER, etc.) that many modems still lack today. These operations were handled directly by software on the host computer; the modem set certain registers when tones were heard on the line, by timing when these registers were set or clear, the software could determine what was happening on the line.

The Apple-CAT II also supported the Bell 202 protocol, which allowed half-duplex 1200 bit/s operation when connecting to another Apple-CAT II modem. 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. Since the 1200 bit/s mode was half-duplex, or one-way only, the users would normally have to decide in advance which direction transmissions would proceed.

However, software was used to work around this limitation as well. File transfer programs 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. Many bulletin board systems (BBSs) running CatSend and then CatFur were set up to transfer warez. The 202 CatFur protocol could only be used by a user running another APPLE-CAT II.

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