Macintosh Quadra 660AV
|Release date||July 29, 1993|
|Discontinued||September 12, 1994|
|Operating system||System 7.1–Mac OS 8.1, or with PowerPC upgrade Mac OS 9.1|
|CPU||Motorola 68040 @ 25 MHz|
|Memory||8 MB, expandable to 68 MB (60 ns 72-pin SIMM)|
The Macintosh Quadra 660AV (Codename: "Tempest") is a personal computer that is a part of Apple Computer's Quadra series of Macintosh computers. When it was originally introduced in July 1993 alongside the Quadra 840 AV it was called the Macintosh Centris 660AV, but it was renamed without any major changes in the hardware when the Centris line was abandoned in October 1993. It was discontinued in September 1994, with no immediate replacement - however, the AV versions of the Power Macintosh 6100 that had already been introduced had a very similar position in Apple's product lineup.
The 660AV uses the "pizza box" case of the earlier Centris 610, which somewhat resembled the case of the Amiga 1000, another computer commonly used in desktop video during the era. 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 deep 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 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. 
- Centris 660AV and Quadra 660AV specifications at AppleSpec
- Quadra 660AV at apple-history.com
- Quadra 660AV at Low End Mac
- Centris 660AV and Quadra 660AV at EveryMac.com