Michael Nadeau and Tom R. Halfhill
The PowerPC is poised to challenge Intel processors on the desktop. But what about portable systems? Here, it seems, Intel is at an even greater disadvantage. Its current fastest 486 and Pentium processors are slower and more power-hungry than the PowerPC 603. Building notebooks and subnotebooks with these Intel chips presents difficult engineering challenges, making the PowerPC all the more attractive to manufacturers of battery-powered systems.
But don't count out Intel in the portable arena yet. Its recently announced 486DX4 addresses both power management and performance issues.
The DX4's name is misleading. The trio of DX4 chips recently announced by Intel are actually clock-tripled, running their internal clocks at about three times the speed of
their external buses. In fact, one of them runs only 2.5 times faster than its I/O bus. Still, at 100 MHz, 83 MHz, and 75 MHz, they are among the fastest 486-class microprocessors.
The DX4 chips also introduce other improvements, including 3.3-V operation; pin compatibility with existing 486 sockets and 5-V parts; lower power consumption and heat dissipation; 0.6-micron process technology; and a 16-KB instruction/data cache, twice as big as a normal Intel 486 cache. All have on-board FPUs and SL Enhanced power management.
The 486DX4-100 can operate its external bus at 33 or 50 MHz. It is available now and costs $649 in 1000-unit quantities; Intel says the price will drop to $580 in the second quarter.
Also available is the 486DX4-75, which has a 25-MHz bus. The 1000-unit pricing is $499 (expected to drop to $475 in the second quarter). Rounding out the line is the 486DX4-83, a not-quite-tripled processor with a 33-MHz bus. It won't ship until the second half of this year; prices are not
yet available.
BYTE tested a beta version of the first DX4-powered notebook, the Texas Instruments TravelMate 4000E. Similar in design to the other TravelMate models, it features a 75-MHz version of the DX4 and an active-matrix color display.
The system uses the same power management circuitry as TI's other 486 notebooks. TI takes pride in its ability to squeeze operating time out of a battery, and BYTE's battery tests have consistently rated its systems highly in this category. So TI is probably the best company to first show a DX4 notebook.
Under heavy use with a lot of hard disk accesses, we got about 21/2 hours of battery time--a respectable showing, given the performance and color display. But TI doesn't deserve all the credit: Intel lowered power requirements on the DX4 to 2.5 to 3 W, from about 4 W on a DX2. The 3.3-V operation and SL Enhanced features help, too.
In raw performance, the 4000E scored a 2.32 on the CPU tests--about 10 percent faster than the 486DX-powered Comp
aq Deskpro 66M and 20 percent slower than the Pentium-based ALR Evolution V. (Note that the TI system uses the slowest DX4.) On the FPU side, the Pentium systems have a much bigger (about 70 percent) advantage.
Compared to other notebooks, the application-level results were much more impressive. The 4000E is 3.25 times faster than the IBM ThinkPad 500 (which uses a 50-MHz IBM 486SLC2) on DOS applications, and 4.5 times faster on Windows applications. Much of this advantage can be attributed to the fact that the DX4 has an FPU and the 486SLC2 does not.
The 4000E is a premium system with a premium price--$4499 for the tested model. However, you get a 6-pound color notebook with reasonable battery life that will run your applications faster than most DOS/Windows desktop PCs. That's a good reason to bet on Intel remaining at the top of the notebook processor heap for the foreseeable future.
Photograph: The TI TravelMate 4000E.
Illustration: 486DX4 Benchmark Results
Th
e DX4's CPU performance falls between the 66-MHz 486DX's (Compaq) and the 60-MHz Pentium's (ALR). For CPU and FPU tests, a Compaq Deskpro 386/33 = 1. In the DOS application indexes, the big difference is the DX4's FPU; neither the Cyrix 486SLC (Epson ActionNote) nor the IBM 486SLC2 (ThinkPad 500) has one. This gave the DX4 a huge advantage on math-intensive tasks such as spreadsheet recalcs and database indexing. For the application indexes, a Toshiba
T2200SX = 1.
Michael Nadeau is a BYTE senior editor, and Tom R. Halfhill is a BYTE senior news editor based in San Mateo, California. You can reach them on the Internet or BIX at
miken@bix.com
and
thalfhill@bix.com
, respectively.
Intel, TI Show Off the 486DX4
