nitower. The minitower resembles the Power Mac 8500 in capabilities, but it sports a Power Mac 9600-style, easy-to-service chassis.
The systems come with 32 MB of industry-standard SDRAM, three PCI slots, internal and external SCSI interfaces, a built-in 10Base-T Ethern
et interface, and ATI 3D Rage II+ accelerated graphics hardware with 2 MB of SGRAM. Storage peripherals include a 24x ATAPI CD-ROM drive, and a choice of a 4- or 6-GB IDE drive. The hard drive platters rotate at 5400 rpm to improve access time. An internal Iomega Zip drive is available as an option.
The PowerPC 750 is a highly enhanced version of the PowerPC 603e's microarchitecture. It delivers 604e-calibre performance in a low-cost design (see "First Look at PowerPC G3" in the April 1997 BYTE for more information).
In Apple's desktop system, the processor runs at either 233 or 266 MHz, while in the minitower it runs at 266 MHz. These systems have a 512-KB L2 cache connected to the 750's 64-bit backside bus, and the cache operates at half the processor speed (117 or 133 MHz). Significantly, a new main logic board design uses revamped memory-controller and PCI-bridge ASICs that let the system bus operate at 66 MHz, which boosts system throughput. The main logic board also allows tailored hardwar
e enhancements through a "personality" module.
On the desktop system, the personality module provides 16-bit stereo sound I/O and a communications slot for a modem card; on the minitower the module provides video capture and video output capabilities in addition to the sound I/O and modem slot.
BYTEmark tests we ran on a preliminary 266-MHz desktop G3 system show the PowerPC 750's potential. As
the chart
indicates, the Power Mac G3 didn't beat a Power Mac 9600 equipped with a 350-MHz PowerPC 604e, but it came close in terms of raw integer performance. The G3 also decisively beat a 300-MHz Pentium II in the BYTEmark tests.
The Photoshop 4.0 tests provide a better picture of each system's application performance. The synthetic BYTEmarks measure only raw CPU performance, whereas the Photoshop tests do a better job of exercising the CPU, secondary cache bus, and system bus without emphasizing hard drive and video card performance.
We tested two different Power Macs
-- the Power Mac 9600 and the G3-based system -- and a 300-MHz Pentium II-based PC from AST running Windows NT 4. All three systems had 64 MB of RAM to minimize the effect of the different hard drives' performance. The Photoshop tests were conducted with the same display resolution and color depth (1024 by 768, 24-bit color). To minimize the influence of different video cards in each system, we counted only the time required to complete each operation rather than also counting additional time required for the screen to redraw.
The Photoshop tests indicate that the G3's faster system bus (66 MHz) and L2 cache (133 MHz) help the 266-MHz Power Mac G3 beat the Power Mac 9600 by a nose on several tests. Even though the 9600's 604e CPU was running at 350 MHz, its in-line L2 cache bus was running at 100 MHz, and its system bus at just 50 MHz.
When you look at the bottom line, the Power Mac G3 is a winner in price as well: A 233-MHz desktop Power Mac G3 costs $1999, a 266-MHz desktop P
ower Mac G3 with a Zip drive costs $2399, and the 266- MHz minitower model with a Zip drive costs $2999.
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Apple Macs Get Faster and More Affordable
