Macintosh Quadra

The Macintosh Quadra is a family of personal computers designed, manufactured and sold by Apple Computer, Inc. from October 1991 to October 1995. The Quadra, named for the Motorola 68040 central processing unit, replaced the Macintosh II family as the high-end Macintosh model.

The first models were the Quadra 700 and Quadra 900, both introduced in October 1991, with the latter discontinued after six months and replaced by the Quadra 950. The Quadra 800 was added in February 1993 (succeeding the Quadra 700), followed the multimedia-focused 840AV at the end of July 1993. The Macintosh Centris line was merged with the Quadra in October 1993, adding the 610, 650 and 660AV to the range. The 605 (also sold as the Performa 475 or LC 475) was also introduced in October 1993, featuring the 68LC040 (lacking an FPU) as standard although it could be upgraded to the full 68040. After the introduction of the Power Macintosh line in early 1994, the Quadra 630 (using the "full" Motorola 68040 instead of the LC's 68LC040) became the last new Quadra member. The Quadra 950 continued to be sold until October 1995.

The product manager for the Quadra family was Frank Casanova who was also the Product Manager for the Macintosh IIfx.

The first computers bearing the Macintosh Quadra name were the Quadra 700 and Quadra 900, both introduced in 1991 with a central processing unit (CPU) speed of 25 MHz. The 700 featured identical case dimensions as the Macintosh IIci but vertically oriented as a mini-tower, with a Processor Direct Slot (PDS) expansion slot, while the latter was a newly designed full-tower case with five NuBus expansion slots and one PDS slot. The 900 was replaced in 1992 with the very similar Quadra 950, with a faster CPU speed of 33 MHz and improved graphics support.

The Quadra 800 was added in February 1993. It was positioned below the flagship Quadra 950 and succeeded the Quadra 700 (which was discontinued shortly after the Quadra 800's announcement). Debuting at half the price of the Quadra 950, the Quadra 800 featured the same Motorola 68040 33 MHz processor as the 950 but its additional interleaved RAM running at 70 ns, as well as an enhanced video system and SCSI bus, enabled it to outperform the 950. The Quadra 800's mid-tower case had four drive bays, giving it more expansion options than the Quadra 700's mini-tower, while having a form factor still considerably shorter than the Quadra 900/950's full tower.

In July 1993, the Quadra 840AV and 660AV (originally branded as Centris 660AV) were introduced at 40 MHz and 25 MHz respectively. They included an AT&T 3210 Digital signal processor and S-Video and composite video input/output ports, as well as CD-quality microphone and audio output ports. The AV models also introduced PlainTalk, consisting of the text-to-speech software MacinTalk Pro and speech control (although not dictation). However, all of these features were poorly supported in software and a DSP was not installed in later AV Macs, which were based on the more powerful PowerPC 601 - a CPU powerful enough to handle the coprocessor's duties on its own.

The Quadra name was also used for the successors to the Centris models that briefly existed during 1993: the 610, the 650 and the 660AV. Centris was a "mid-range" line of systems (featuring slower 68040 CPUs, often the 68LC040 which omits the FPU), between the existing Quadra on the high end (featuring the faster 68040 CPU) and the LC on the low end (built around the 68030 CPU), but it was later decided that there were too many product lines and so Centris was dropped in October 1993.

The 605 (also sold as the Performa 475 or LC 475) was also introduced in October 1993, featuring the 68LC040 as standard although it could be upgraded to the full 68040. At that point, the Quadra lineup consisted of the 950 using a full tower case, the "800-series" machines with a Mid-tower case design (Quadra 800 and 840AV), and the "600-series" (the Quadra 605, Quadra 610 and 660AV had pizza box desktop cases, while the Quadra 650 had a taller desktop case).