Beginning with the AV Macs (the Quadra and Centris 660AV/840AV) Apple replaced the standard modem Serial port with a new connector called the GeoPort. The presence of a GeoPort type serial port can be noted by the looking for an additional ninth pin in the serial connector. The ninth pin carries power from the Mac to a device called a GeoPort Telecom Adapter or Phone Pod. This is a little box that, combined with the internal hardware in these Macs, can replace a modem.
The GeoPort technology takes advantage of the Digital Signal Processing chips in the AV Macs to let the computer itself take on many of the functions previously performed by the modem. With old style modem technology, the computer would send a modem a digital signal, which the modem converted to an analog signal and sent out to the telephone lines.
All Power Macs have GeoPort-enabled printer and modem ports, as do the older Centris 660AV, Quadra 660AV, and Quadra 840AV. GeoPort-enabled serial ports have the ability to transmit data at 115,000Bps, faster than ordinary Mac serial ports, which have a limit of 56,000Bps. This is faster than ordinary modem traffic, but is useful when modems use compression and when you are connecting to ISDN lines. GeoPort connectors look the same as the traditional round Mac serial ports, but have 9 pins, one more than the traditional Mac serial ports.
To connect to an analog telephone line or a digital ISDN line, GeoPort requires the use of a telecommunications adapter. The most common is the Apple GeoPort Telecom Adapter (see the following figure), which connects to standard telephone lines. Like a modem, the Adapter has two connectors, one for a telephone line and one for a telephone.
The first ISDN adapter for GeoPort is the Sat-Sagem SPIGA, which has two ISDN B channels at 64Kbps each, which can be combined.
There are several advantages to using a GeoPort adapter and a software modem instead of ordinary modem, and a few disadvantages. One advantage is that there is some really innovative telephony software available that is easy to set up, use, and manage. For instance, MegaPhone from Cypress research turns your Mac into a full-duplex speaker phone, which means that you and the party at the other end of the line can speak at the same time.
Another advantage is that you can use the same line for both fax and voice without having to turn anything on or off. The Express Modem software can recognize what type of call is received and use the appropriate software, fax or voice, to either answer the call or let you answer it.
Another bonus is that upgrades can be inexpensive software-only additions. At press time, Apple was expected to offer a 28.8Kbps software upgrade for the Apple GeoPort Telecom Adapter sometime during the summer of 1996. Previous to this upgrade, the top speed of the Express Modem and the Apple GeoPort Telecom Adapter was only 14.4Kbps, which is one of the disadvantages to using GeoPort technology.
There is also an annoying incompatibility with the Power Macintosh 7200 series, the 7500/100, the 8500/120, and the 9500 series. With these machines, you must disable LocalTalk in order to use a GeoPort Telecom Adapter by disconnecting any devices attached to the printer port. (Serial printers, which are not LocalTalk devices, can remain attached).
The GeoPort lets the Macintosh perform this translation from digital to analog and back again without the need for a modem. To use the GeoPort, you simply connect a GeoPort Telecom Adapter to your telephone line and into the GeoPort on your Mac. The Adapter is about the same size as a mouse and has, in addition to the GeoPort cable and connector, a pair of phone jacks (incoming and outgoing).
The GeoPort provides for backward compatibility with existing serial products, in addition to its new features set. You can plug an ordinary modem or fax/modem into the GeoPort or use any other device that attaches through a conventional serial port. The extra pin socket won’t interfere.
The GeoPort technology makes the Mac uniquely suited to answer and process incoming telephone calls. It’s bundled with ApplePhone software, which lets your AV Mac turn itself into a phone-answering machine and speakerphone. By giving computer the power to interface directly the Mac can act as a complete voice mail system, in addition to processing standard data and fax telephone calls. ApplePhone has a screen display that mimics a real phone and answering machine, right down to the blinking lights.