The 660AV uses the "pizza box" case of the earlier Centris 610. The 660AV has a full Motorola 68040 instead of the 610's FPU-less 68LC040. Like the 840AV, the 660AV features video input/output capability and an onboard AT&T 3210 digital signal processor (here clocked at 55 MHz) to make the video handling less of a burden on the CPU.
Some of the earliest Centris 660AVs have the older 'auto-inject' floppy drive opening similar to the 610 (as seen in the image), but most of the Centris models and all of the Quadra models have a drive similar to the Power Macintosh 6100, lacking the ‘auto-inject’ feature. These models have a round indent at the center of the floppy drive slot to make it possible to insert the disk all the way.
The Quadra AV Macs introduced a new universal ROM (codenamed SuperMario) that would be later be used in all PowerPC Macs. It includes SCSI Manager 4.3 and Sound Manager 3.0. It also is "vectorized" making it easier to patch.
Talking and listening to a Mac Quadra 840 AV. (Apple Macintosh Quadra 840av 680x0-based microcomputer; PlainTalk voice recognition software)
Feb 01, 1994; The audiovisual model of the latest Macintosh computer, Quadra 840 AV, comes equipped with Apple's new speech technology,...