modems without the expansion card, but concluded that "Apple users shopping for a modem would be wise to consider this system very carefully". 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. At the Apple-CAT II's peak, compatibility with its native API increased, and MMII emulation became less of a necessity. The D-CAT A direct-connect version of the original 300 bit/s external modem was later released as the D-CAT. The "D" stood for "direct": the modem was directly connected into the handset jack of the telephone instead of requiring acoustic coupling. To operate the D-CAT, a number was dialed on the telephone and the user waited for a carrier signal from the modem being called, just as with an acoustic modem. When a carrier signal was received, a button was pressed on the D-CAT which made it produce a carrier signal and establish a connection with the modem being called, then the handset would be left off-hook. A further improvement was the Auto-CAT, which allowed dialing the phone by entering the number when the modem was first started. Once the connection was made, the modem switched to "data mode", and from then on had to be operated manually. The J-CAT The J-CAT was Novation's first attempt to make a "smart modem", albeit in a rather non-standard fashion. 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. In an era when it could be safely assumed that the remote user would hang up when they were finished their call, as they were likely using an acoustic coupler modem like the original CAT, the lack of a "hang up my phone" command was not a real problem. This made the J-CAT useful for BBS use; Novation ran a simple one to allow users to test their new modems. The J-CAT also supported another non-standard feature that allowed direct control of the phone line. 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