There aren't that many Amiga 1200 owners who've never heard of the clockport. But for those of you who haven't, the clockport is a nifty little connection right in the heart of the Amiga 1200, originally intended for connecting a battery-backed clock and RAM expansion to. However, it was very rarely used for that and was largely forgotten until people suddenly realised that it was quite a versatile port, with good, reliable access to the system's buses, access to interrupts and so on. These people then designed all manner of add-ons to be used on this connector, ranging from faster serial & parallel ports to the CatWeasel floppy drive controller, sound cards, USB controllers, even MP3 decoders. For the A1200 with its limited expansion possibilities, this was an incredible opportunity to use peripherals which would otherwise require expensive and/or undesirable tower conversions and Zorro/PCI bus extensions.
A New Problem...
This was all well and good, until people started to want to use more peripherals on their machines, and found that only one clockport couldn't cut it. Moreover, people with other machines (A4000s, A600s etc.) were also disappointed that they couldn't take advantage of all these shiny new add-ons. So the clever peripheral engineers and programmers decided to use slightly more clever addressing routines which allowed "shadow" clockports to be created and, with some electronic trickery and driver modification, these shadow clockports could be used for additional devices. It also meant that Zorro cards or hacks could add clockports to almost any Amiga by mapping it to one of the shadow addresses, or even another address entirely if the driver allows it.