J12: It was actually a common hack back in the day to mount a 20 pin boxed header here and connect a surplus Mac floppy drive to it - worked out cheaper than buying a USB FDD, if you knew what you were doing, and saved a USB port. It was basically a case of soldering the header on, connecting the cable, running it out the side of the iMac, and plugging the drive in.
J11: No clue, I'll have to have a look at my spare.
J4: Yes, this is a serial port, used for the IrDA module in the Rev. A and B Bondi iMacs.
J2: Yes, this is an ADB port, provided you solder on some resistors and a few other things, you can use ADB devices on an MiniDIN-4 connector installed here. I remember seeing a page where some Japanese guy had managed to get it working.
J6: On the Rev. A and B Bondi iMacs that have IrDA, this has a cable connected to it, that goes to the serial port on the bottom, in the same fashion as what you see with the video and audio connectors.
DS2,3,4: I've never noticed these before, to say the least, I'll have to have a look! interesting.
S2: No idea, I'll have to have a look at mine.
MEZZANINE: This is where the Mezzanine slot is installed on the Rev. A and B Bondi iMacs. This was put in by Apple for testing purposes, but seems to offer access to the iMac's PCI bus. After this was discovered, a couple of cards were actually made for this slot - MicroConversions made a version of their Voodoo2 graphics accelerator that fit this slot, and someone else made an UltraSCSI card. Best of luck finding either of them though.
J11: No clue, I'll have to have a look at my spare.
J4: Yes, this is a serial port, used for the IrDA module in the Rev. A and B Bondi iMacs.
J2: Yes, this is an ADB port, provided you solder on some resistors and a few other things, you can use ADB devices on an MiniDIN-4 connector installed here. I remember seeing a page where some Japanese guy had managed to get it working.
J6: On the Rev. A and B Bondi iMacs that have IrDA, this has a cable connected to it, that goes to the serial port on the bottom, in the same fashion as what you see with the video and audio connectors.
DS2,3,4: I've never noticed these before, to say the least, I'll have to have a look! interesting.
S2: No idea, I'll have to have a look at mine.
MEZZANINE: This is where the Mezzanine slot is installed on the Rev. A and B Bondi iMacs. This was put in by Apple for testing purposes, but seems to offer access to the iMac's PCI bus. After this was discovered, a couple of cards were actually made for this slot - MicroConversions made a version of their Voodoo2 graphics accelerator that fit this slot, and someone else made an UltraSCSI card. Best of luck finding either of them though.