Second Class Macs & Road Apples

GeoPort 'Modems'

three

Dan Knight - 1998.04.10

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.

Low End Mac is an independent publication and has not been authorized, sponsored, or otherwise approved by Apple Inc. Opinions expressed are those of their authors and may not reflect the opinion of Cobweb Publishing. Advice is presented in good faith, but what works for one may not work for all.
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