Apple introduced the Macintosh Centris 610 along with the more powerful Centris 650 on February 10, 1993. The short-lived Centris line only included three models, the 610, 650, and 660AV (introduced in July 1993), and lasted only 9 months. Apple positioned Centris computers in the midrange of its line up with the 610 being the low cost leader. The Centris 610 ranged in price from $1859 to $2959 depending on options. I purchased my 610 in 2006 for $30.
The Centris 610 uses the same 68LC040 processor found in the 25 MHz Centris 650, but the 610's processor is only 20 MHz. Unlike the 650, Apple provided no option to get configurations with a full 68040, which included a math coprocessor (FPU). Nor was there an option to replace the low cost 68LC040 with a full 68040. Apple's reasoning for not including the option on the 610 is its cramped case. A math coprocessor generates extra heat, which would require a heat sink, and there is little room for such a device in the 610's slim-line case. Furthermore, people who needed a math coprocessor likely needed a faster processor and more expansion options than a slim-line Mac provided, so the limitation didn't affect the 610's intended users. Apple's reasoning didn't stand the test of time. Future model Quadras using the same case design as the Centris 610 shipped with full 68040 processors.
The Centris 610 has a single slot for expansion that can be used to install a 7-inch NuBus Card. Regular NuBus cards in 1993 were typically 12 inches. The slot is actually a Processor Direct Slot (PDS) that requires a special adapter to accept 7-inch NuBus cards. Apple sold this adapter for $99. The adapter angles the NuBus card 90 degrees, perpendicular to the motherboard. A horizontal port door is provided for cards that require one. The 7-inch limitation was particularly bothersome for owners of older NuBus boards, which was a popular way to add functionality to Macs in those days. At the time the 610 shipped, few vendors actually offered 7-inch boards. Vendors designed Mac NuBus boards to fit in older Macs like the Macintosh II, which were expansive with plenty of room for internal expansion. The industry was moving towards the smaller 7-inch cards at the time the Centris 610 shipped.
Centris 610 motherboard
The 610 has the following built-in ports: two ADB ports, one DB-15 video port, one DB-25 SCSI port, one serial modem port, one serial printer port, one microphone jack, and one audio-out jack. Apple included an AAUI-15 Ethernet port on more expensive models. My 610 is a base model and thus does not have this port. The 610 does not have an internal microphone. Apple offered an external microphone but did not include it for free with the Centris 610.
Centris 610 ports
The logic board has 4 MB RAM soldered on it, and can accept 4 MB, 8 MB, 16 MB, and 32 MB 72-pin SIMMs. The Centris 610 has two RAM slots and can accept up to a maximum of 68 MB RAM. The RAM slots can be filled independently, but if the RAM SIMMs used are not the same speed, the faster SIMM should be in the front-most slot, bank 0. My 610 has 40 MB RAM. The Centris 610 originally shipped with Mac OS 7.1 and can support up to Mac OS 8.0. My 610 is using its original factory installed operating system, Mac OS 7.1.
The Centris 610 is capable of displaying a variety of resolutions beginning at 512 x 384 and ending at 1152 x 870. The built-in video circuitry comes with 512K VRAM (video RAM), enough to drive 16-inch and smaller monitors at 8-bit color depth (256 colors). The VRAM is expandable to 1 MB to handle these same monitors at 16-bit color depth (thousands of colors). The 610 has two VRAM slots that can each accept 256K VRAM SIMMs. My 610 does not any additional VRAM installed. The 512K built-in VRAM in my 610 displays 256 colors (8-bit) on an Apple Color Plus 14-inch Display (M1787) with a fixed resolution of 640 x 480.
The Centris 610 shipped with either an 80 or 230 MB internal SCSI hard drive. My 610 has an 80 MB internal hard drive. All models included a 1.4 MB internal floppy disk drive. There is a third drive bay for a removable storage device (up to 5.25 inches tall). Apple offered a CD bundle that cost $2959. The bundle included 8 MB of RAM, 1 MB of VRAM, a 230 MB internal hard drive, a microphone, and the AppleCD 300i CD-ROM drive.
The pricing scheme for the Centris 610 was as following:
$1859, 4 MB RAM, 512K VRAM, 80 MB hard drive
$2149, 8 MB RAM, 512K VRAM, 80 MB hard drive, AAUI-15 Ethernet port
$2519, 8 MB RAM, 512K VRAM, 230 MB hard drive, AAUI-15 Ethernet port
$2959, 8 MB RAM, 1 MB VRAM, 230 MB hard drive, AAUI-15 Ethernet port, Apple CD 300i CD-ROM drive
Apple intended the 610 to compete head-on with similarly configured 486 PCs, but a direct comparison was difficult because the slim-line PCs available at the time offered four to eight expansion slots and they were obviously not as slim as the 610. A similarly powered, full-sized Windows PC cost as much as $1000 less than the Centris 610. A more relevant comparison many potential buyers considered was between the Centris 610 and the 68030-based Macintosh IIvx. The prices were comparable for similarly equipped models. The choice between these two contemporary Macs was power or expandability. The IIvx offered greater expandability, but the Centris 610 offered a faster processor.
What's in a name?
The Centris line only lasted 9 months and included only three models: the Centris 610, the Centris 650, and the Centris 660AV. Apple positioned the Centris computers in the midrange. They were not exactly inexpensive, but rather affordable for business users and professionals who needed a little more power than that available in the LC and compact lines of low cost computers or the older Macintosh II line. Although Centris is not part of its name, the Macintosh IIvx was actually part of the Centris midrange line. Apple lawyers were not able to complete the trademark check for the Centris name before the IIvx was released four months ahead of the Centris 650 and 610.
The Centris line was intended to represent the midpoint between the low-end Macs and the high-end Quadra series. The Centris label turned out to be confusing to consumers and was quickly abandoned. After only 9 months, the Quadra 610 and 650 replaced the Centris 610 and 650. The Quadra 610 and 650 kept the basic case and design of their Centris counterparts, but raised the CPU speeds from 20 MHz and 25 MHz to 25 MHz and 33 MHz respectively. The Centris 660AV was re-banded as the Quadra 660AV and sold with a full 68040 processor. The Centris 610's case design was particularly long-lived. It would go on to serve in the Power Macintosh 6100 series and the Performa 6100 series.