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Making modern iMac G3 Mezzanine peripherals

joshc

Well-known member
The idea is to build a modern SD and CF card adapter for the iMac, that way, you can use SD cards and CompactFlash and transfer files between the modern web and the old mac. I think that would be useful.
Or just plug in a USB card reader? There you go, job done !

If you actually want an easy way of transferring files to an iMac, just network it. That's way easier than faffing with SD/CF cards.

Just because the Mezannine slot is there, it doesn't have to be used. ;)

The other big problem with this is that the Mezannine slot was not officially supported by Apple - it was for connecting a logic analyzer to quickly diagnose board problems. It was never intended for upgrade cards.

More info here including info from a former Apple employee: https://www.applefritter.com/node/2302

If anything, it might be interesting to experiment with the Mezannine slot a bit, but to avoid dissapointment, I certainly wouldn't plan to do anything serious with it.

@Angelgreat Do you have an iMac with a mezannine slot to experiment with?
 
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chelseayr

Well-known member
@Cory don't mind me sounding a little like a rant here;
I have to agree that theres a difference between an imac being 'with what it came with' and a 9600 where you're free to run crazy with six full-length pci cards for all sort of random craps? :p

@joshc I did always somewhat think that the tray-loaded imacs were a little unusual as far as internals went. and do I have to mention the few website examples of people literally routing a ribbon through the side of the casing and have a disk drive running loose on the table. but of course the slot-loaded boards (as I understand?) not just removed the circuit for the port but also the controller itself too. at least for the no-hacks-pls people theres still these relatively-inexpensive imation disk drives via usb on pretty much any classified/auction sites
 

volvo242gt

Well-known member
^This. There's an article about the floppy drive mod for the Revision A iMacs in one of the old MacAddict magazines. If I owned one, I probably would've gone ahead and done the mod, turning it into a hopped up, nicer looking version of a MolarMac... Probably could take a junk Apple II I/O Controller Card's DB-19 port off, wire it up to a 20-pin floppy drive cable, then mount it to a plate that went in place of the cover that got opened up to allow the 20 pin cable to stick through with the Mitsubishi-branded floppy drive hanging off of it. Modify an old A9M0106 floppy drive housing to take the manual-inject mechanism, then have an external floppy drive that plugs into the floppy port on the side of the iMac.

There was a change with the second generation PowerMacs that prevented them from working properly with the auto-inject Sony drives, btw. Otherwise, you could take an upgraded A9M0106 or a factory external SuperDrive and use it with the iMac. Since the early G3 machines (early iMacs included) came after the 7200/7500/8500/9500 machines, they probably are the same.
 

Gorgonops

Moderator
Staff member
My vague recollection is that either a firmware update or a change to the "New World" soft-rom file broke the floppy drive hack a year or two after the iMac came out; said firmware update was supposedly non-negotiable for one of the OS 9 upgrades? Don't take this as gospel, it's a *very vague* recollection.

The thing to remember about the iMac is it is almost the same chipset as the Beige G3; the ethernet onboard the integrated I/O bridge, "Paddington", was upgraded to 100mb/s but it still contained the integrated SWIM3 and serial ports. (I think it did dump the MESH SCSI of "Heathrow"? Or if it was still there on the chip I don't think any that used it brought it out to headers.) It has essentially the same ATI video chipset as well so... I'm not sure I'd call a Rev. A iMac a "hopped up" MolarMac; it really is pretty much the same thing minus the ample closet space.
 

Angelgreat

Well-known member
Another idea for the mezzanine slot, make a adapter to use a original AirPort card on it. That way, you can make the Bondi Blue wireless!
 
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