The serial ports on Pippin consoles are controlled by a Zilog Z85C30 Serial Communication Controller, capable of LocalTalk speeds up to 230.4 kbps. Many early Macs typically had two Mini-DIN-8 serial ports, labeled for a printer and modem. The GeoPort specification adds a 9th pin to the serial port to supply 5 volts of DC power. A GeoPort is backwards-compatible with standard Mini-DIN-8 serial devices, but 9-pin peripherals cannot be plugged into an older 8-pin serial port.
Attaching a GeoPort Telecom Adapter to a GeoPort-ready serial port (labeled with a globe symbol on Pippin consoles) allows it to emulate and function as a (relatively) low-cost modem without an external power supply, at the expense of CPU overhead. The GeoPort's functionality was also integrated into Apple's proprietary Comm Slot II in some PowerPC-based Macintosh desktop computers, but has since been discontinued.
Telecom Adapter modelsEdit
GeoPort Telecom Adapters shipped with varying modem connection speeds, and could be upgraded through software updates. Using one on a Pippin console would require a "Pippinized" CD-ROM that includes support for use of the GeoPort.
- GeoPort Telecom Adapter M1694LL/B - 14.4 kilobaud (kbps)
- GeoPort Telecom Adapter (II) M2117LL/A - 28.8 kilobaud (kbps)
- GeoPort Telecom Adapter II M5438LL/A - 33.6 kilobaud (kbps)
Telecom Adapters vs conventional modemsEdit
Pippin Atmark consoles in Japan shipped with an actual 14.4 kilobaud modem (PA-82007) which was not a GeoPort Telecom Adapter, thus reducing CPU overhead. However, its attached 9-pin connector cable was capable of drawing power from the GeoPort and did not require an external power supply. Pippin @WORLD consoles in the United States shipped with a re-branded 28.8 kilobaud Motorola ModemSURFR, which came with its own separate power supply. Some third party manufacturers, such as Global Village, also created conventional modems that could draw power from the 9th pin of GeoPort-equiped Macs to eliminate the need for a power supply, like Pippin modems.
- ↑ 1.0 1.1 1.2 GeoPort 'Modems' by Daniel Knight, Low End Mac. 1998-04-10.
- ↑ Apple’s Pippin and Bandai’s @World: Missing the Mark(et), Low End Mac. 2006-09-22.
- ↑ Macintosh Serial Throughput by Daniel Knight, Low End Mac. 1998-04-12.
- ↑ 4.0 4.1 Making a Universal Teleport Gold IIP modem. by James Lockman.
- ↑ Apple's Geo Modem, The 6400 Zone. 2003-06-17.
- ↑ Les modems de la Pippin (French) by Pierre Dandumont, Journal du Lapin. 2016-09-24.
- ↑ #1 Temporal Loop - Birth of the iMac by Thomas Hormby, The Mac Observer. 2007-05-25.