Power Macintosh 6100 DOS Compatible
The Power Macintosh 6100/66 DOS Compatible is a Power Macintosh 6100/66 sold with Apple's DOS Compatibility card, which carries an Intel 486DX2 processor running at 66 MHz so that the machine can run MS-DOS and Windows software alongside the Mac OS. Apple introduced it on January 3, 1995 and discontinued it on May 18, 1996, after the rest of the 6100 range.[1] EveryMac lists it as the 6100/66 (PC), order number M3972LL/A, at US$2,150 with a 500 MB drive and 2× CD-ROM.[2]
Apple also sold the card as a DOS Compatibility Upgrade kit for other 6100s, and its service manual covers both.[3] Apart from the card, the computer is a standard 6100/66; see Power Macintosh 6100 for the logic board, memory rules and ports.

The DOS Compatibility card
The card occupies the 6100's single expansion slot. It sits in a bracket with an adapter card whose connector plugs into the slot on the logic board, and a tab on the adapter slides into a slot in the bottom housing (pp. 75, 135–136). Because the slot is used, the machine cannot take a processor-direct or NuBus card as well, and Apple says the card cannot be fitted to a 6100/60AV, whose slot holds the AV card (p. 126).[3] Apple's specification page lists the slot as "PDS filled" and the second processor as an Intel 486DX2-66.[1] EveryMac describes it as a NuBus card with up to 32 MB of its own RAM; Apple's service manual shows it in the processor-direct slot through its adapter.[2][3]
The upgrade kit contains the card in its bracket adapter, a four-headed monitor cable, a monitor cable adapter, a hard drive power extension cable, a CD-ROM audio cable and two thumbscrews (p. 127).[3] Installation, from Apple's procedure (pp. 128–139):
- Remove the top housing and the expansion port cover on the rear panel.
- Fit the hard drive power extension cable between the power supply cable and the hard drive, routed round the standoff.
- Route CD audio through the card: with a CD-ROM drive, the drive's audio cable goes to CD In on the card and the kit's cable runs from Sound Out on the card to the CD audio connector on the logic board. Without a CD-ROM drive, only the Sound Out cable is fitted.
- Check that the jumper at J10 is in the "SX" position, over the two right-most prongs. Apple says J10 is mismarked and the card may misbehave otherwise.
- Fold the SCSI ribbon back over the card, hold the hard drive power cable clear, insert the adapter card connector into the expansion slot and fit the thumbscrews.
- Plug the HDI-45 end of the monitor adapter cable into the computer's monitor port, the four-headed cable's male DB-15 into the adapter, its female DB-15 into the monitor, and its male 26-pin connector into the card.
When a card is returned to Apple, the sound card must first be removed from it (pp. 73, 78).[3]
Faults
| Symptom | Apple's cure |
|---|---|
| Intermittent stack overflow errors in DOS or Windows | Remove the card and check that the J10 jumper is in the "SX" position (over the two right-most prongs). |
| Screen intermittently blank at startup of the DOS Compatibility card | Remove the card and check that the J10 jumper is in the "SX" position. |
Source: service manual p. 54.[3] For every other symptom, use Apple's 6100 charts on Power Macintosh 6100 Troubleshooting.
The clock battery is on the 6100 logic board: 3.6 V lithium per Apple's specification page, replaced below 3.2 V per the service manual (p. 103).[1][3]
Related pages
References
- ↑ 1.0 1.1 1.2 Apple, "Power Macintosh 6100/66 DOS Compatible: Technical Specifications".
- ↑ 2.0 2.1 EveryMac, "Power Macintosh 6100/66 (PC) Specs".
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Apple Computer, Service Source: Power Macintosh 6100/WS 6150 (1996), File:Powermac 6100 series.pdf; see Power Macintosh 6100/ WS 6150 Service Source. Page numbers are PDF pages.