Quadra series

The Quadra series of Macintosh computers was created in 1991 as Apple's high-end professional-grade machines, based on the Motorola 68040 processor. It replaced the Macintosh II series and was succeeded by the PowerPC-based Power Macintosh series in 1994. The first machines that kicked off the line were the 700 and 900, both released in 1991. Apple discontinued the line in 1994, after the release of the Quadra 630.

Models
All of the Quadra computers used Motorola's 68040, which was the last 68k processor Apple used before changing to PowerPC. All used the "full" 68040 processor, which included the FPU except the entry level Quadra 605 which uses the FPU-less 68LC040.
 * Macintosh Quadra 700 (1991)
 * Macintosh Quadra 900 (1991)
 * Macintosh Quadra 950 (1992)
 * Macintosh Quadra 800 (1993)
 * Macintosh Quadra 840AV (1993)
 * Macintosh Quadra 660AV (1993, replaced Centris 660AV)
 * Macintosh Quadra 610 (1993, replaced Centris 610)
 * Macintosh Quadra 650 (1993, replaced Centris 650)
 * Macintosh Quadra 605 (1993)
 * Macintosh Quadra 630 (1994)

Carryover from Centris line
For a very short time in 1993, Apple made computers under the Centris name. It was discontinued a few months after introduction. Only 3 models were made under the Centris name, the 610, 650, and 660AV. The 650 and 660AV used the 68040 and the 610 used the 68LC040. The 610 was upgraded to the 68040, and the line was merged with the Quadra line.