Second Class Macs are Apple's somewhat compromised
hardware designs. For the most part, they're not really bad - simply
designs that didn't meet their full potential. (On our rating scale,
the more brown apples, the worse the hardware.)
Some view the GeoPort Telecom Adapter as brilliant; others as a
bizarre hardware kludge.
The Centris 660av (later Quadra 660av) and Quadra 840av were the first Macs with
GeoPorts, an enhanced serial port. The DMA (direct memory access) ports
can operate at up to 2 megabits per second (Mbps). By contrast, the
typical Mac serial port ran at 230.4 Kbps or less than 1/4 Mbps. (For
more on serial ports, read Macintosh
Serial Throughput.)
With the GeoPort serial port, Apple introduced the GeoPort Telecom
Adapter, commonly (though incorrectly) known as the GeoPort modem. Not
only could the "GeoPod" be used as a 9600 bps modem, it could also fax
and turn your Mac into a speakerphone.
Eventually software enabled the GeoPod to run at 14.4 Kbps, then
28.8 Kbps. No other modem ever offered such an upgrade path.
Of course, there was a cost. In the case of the GeoPort "modems,"
like the earlier Express Modems in
early PowerBooks, the cost was CPU time. The faster it ran and the more
it did, the more it slowed down your computer.
Worse, it tied up the serial port far more than a conventional
modem, affecting printing, MIDI adapters, and LocalTalk networking
adversely. And throughput never seemed as fast as with a conventional
modem on the same computer and phone line. Never.
Like the Apple /// and the twiggy drives in the Lisa, the GeoPod was
a clever hack that didn't live up to expectation. Well after the pod
was discontinued, the idea resurfaced as an internal GeoPort Express
modem in some Performa and Power Mac models.
Maybe Apple realized the folly of their ways and repented with the
Power Mac G3, which explicitly doesn't support the GeoPort
Telecom Adapter.
