G3 AIO Power Supply Jumper

[mcdermd]

Uniserver hooked me up with a Power Mac G3 AIO and while tearing it down, I noticed something I haven't seen on another Mac before - a power supply jumper to switch between a Mac or PS/2 power supply. It's located just above the PCI slots, near the CUDA reset button.

I know that Power Computing and some others used a bog-standard PS/2 supply but hadn't seen it on any Apple branded gear before. Is this unique? Are there any other Macs that can take a standard PS/2 power supply out-of-the-box?

 

[uniserver]

i would think this could have been a nice feature with the Powermac G3/G4's/G5's

 

[aftermac]

From: http://en.wikipedia.org/wiki/Power_Macintosh_G3

The G3 used Apple's new "Gossamer" logic board, which had originally been developed with an eye towards maximum compatibility with PC components. This was known as the "Yellowknife" project, which had sought to develop the first Apple RISC product[clarification needed] — capable of running any OS that would support it, be it Mac OS or Windows.[citation needed] It was an effort by Apple to gain market share, by allowing their hardware to run industry-standard software, but still remaining Mac OS proprietary[citation needed]. The prototype had a ZIF-socket G3 processor, PCI and ISA slots, Mac and PC serial ports, onboard SCSI, PC and Mac floppy drive connectors, ATX power supplies, and PS/2 keyboard and mouse connections, inserted into an ATX case[citation needed]. The project was scrapped by Steve Jobs, after his return to Apple, and his realization of the devastation of Apple's profits due to the Clone makers[citation needed]. Remnants of this effort can be seen in the form factor of the production G3: the logic board's similarity to the PC ATX motherboard standard; solder points for a PC-type floppy drive; and the ability to use both proprietary Apple power supplies and industry-standard ATX power supplies. As a compact and versatile motherboard, the Gossamer board was originally designed to be able to support both the high-end PowerPC 604e and the new PowerPC G3, but when initial tests found that the cheaper G3 outperformed the 604e in many tests, this functionality was removed and Apple's 604e-based systems died a quiet death.

The AIO doesn't use the Gossamer logic board, but it was developed at the same time. I would assume this is all related to the CHRP/PPCP projects that were going on at that time.

 

[mcdermd]

Sure as spit - Looking at my Beige G3 desktop board, it's the same part (820-0991-A) as the one in the AIO and has the Mac/ATX jumper as well. They also have an unpopulated cache header. I never noticed before.

 

[jruschme]

I thought the minitower version of the Beige G3 actually used an ATX supply in a funky bracket.

 

[coius]

The AIO doesn't use the Gossamer logic board, but it was developed at the same time.

Excuse me? yes it does. The only difference is how the screen is hooked up. It goes through the Whisper/Personality card on that header with the clips. In fact it's so similar, I transfered mine to a G3 minitower which eissenfaust88 here on the forum has. I also upgraded it with a G4 Zif. It's the EXACT same board as the rest of the G3 towers, except with a lower end config and a built in screen that attaches to the personality card.

You can see evidence just on the card that goes into the personality slot on any G3. That 9/15 pin header with the clips is just for the monitor on the AIO to connect.

the iMac on the other hand is drastically different. I would akin it slightly more to the blue and white over the beige G3 though.

 

[aftermac]

The AIO doesn't use the Gossamer logic board, but it was developed at the same time.

Excuse me? yes it does. The only difference is how the screen is hooked up. It goes through the Whisper/Personality card on that header with the clips. In fact it's so similar, I transfered mine to a G3 minitower which eissenfaust88 here on the forum has. I also upgraded it with a G4 Zif. It's the EXACT same board as the rest of the G3 towers, except with a lower end config and a built in screen that attaches to the personality card.

You can see evidence just on the card that goes into the personality slot on any G3. That 9/15 pin header with the clips is just for the monitor on the AIO to connect.

the iMac on the other hand is drastically different. I would akin it slightly more to the blue and white over the beige G3 though.

Well, there you go. My mistake it is the same board. That's what happens when you try to post something quick... just got my AIO a couple days ago and haven't torn into it yet.

 

[CC_333]

the iMac on the other hand is drastically different. I would akin it slightly more to the blue and white over the beige G3 though.

My understanding is that the Rev. A thru D iMacs actually had more in common with the Lombard PowerBook, hence the use of laptop RAM and PowerBook-style CPU card.
Also, the beige's were OldWorld, and the iMac was NewWorld (again, like the Lombard, which was, not coincidentally, the first NewWorld PowerBook).

I could be wrong, though, so please take these observations with a grain of salt.

c

 

[coius]

You're right CC. You nailed what machine technically is the closest. I thought i saw the lombard system I have come close to another machine. At least I have been enlightened about that. I believe they use the same chipset and the like as well. Same ATA bus/etc...