Macintosh DOS Compatibility Card

The Macintosh DOS Compatibility Card was made for the Centris 610 and Quadra 610's, but it will work just fine without the bracket in the Centris 650 and Quadra 650 and 800. The card comes with an Intel 486SX-25 processor on it.

There are three basic clock chipping issues to consider; clock chipping the base machine, clock chipping the DOS card, and clock chipping both at the same time.

As far as clock chipping the base Mac, the presence of the Macintosh DOS Compatibility Card does not appear to effect the top speeds attained in the Mac mode, and when in DOS mode it does not appear that the Macintosh DOS Compatibility Card is effected by clock chipping.

As far as clock chipping the Macintosh DOS Compatibility Card itself, I've only heard of clock chipping them in combination with swapping the processor to a 486DX2-66. So to do this you need to replace the 50MHz surface mount oscillator located at G1 to a 66MHz oscillator. And of course swap the processor. Apparently you need to change a few jumpers to get this to work.

Aside from clock chipping, you can also swap the processor on the DOS Compatibility Card.

If you have any more info on this, please pass it along so I can update this info. I also need to go over my old notes.