Systems built for speed
Two years ago, only a few vendors produced Alpha systems, and consumers had a limited choice of packaging, features, and price. Now, finding an Alpha system is easy. Many clone manufacturers, integrators, and system developers build Alpha machines--from longtime Alpha advocates such as Aspen Systems and Carrera Computers to market newcomers such as CompuSys and Advanced Business Technology. Alpha chips are available from two foundries, and two more Alpha foundries might begin producing chips soon. The market's number of resellers is growing, and Alpha systems' prices range from $99 motherboards to $100,000 multiprocessor behemoths. Alpha CPUs span three generations, and available Alpha systems range in age from recently announced to more than 5 years old. Because of the variety of Alphas now available, consumers frequently wonder how to determine a particular Alpha machine's capabilities in relation to other computers. A look at the past and future of Alpha chips will help you understand what is inside different systems and what to expect for the price you pay.
Start at the Bottom
You can find entry-level Alpha systems complete with RAM, a hard disk,
graphics, sound, and network cards for less than $500 in clearance stores. I've even seen new motherboards for less than $100 on the Internet. Digital Equipment calls the chips in most systems at this end of the cost spectrum low-cost Alpha (LCA) processors. These processors have the designations DECchip 21066, 21068, and 21066a. Digital designed them primarily for embedded applications for realtime devices, controllers, and laptops. LCA chips include a cache controller, PCI interface, and rudimentary graphics controller. To achieve this level of integration, LCA processors leave off some components that are standard on most chips. The chips limit the external data bus to 64 bits, use only off-chip cache, offer a maximum of 1MB of cache, and have only 34 external address lines. These limitations reduce LCA chips' complexity, power consumption, cost, and performance. These processors are not the barn burner number crunchers most people expect when they think about Alpha machines.
Digital no longer manufactures LCA chips, and Windows 2000 (Win2K--formerly Windows NT 5.0) doesn't support them. LCA chips came in speeds of 66MHz (the 21068, or LCA4S), 166MHz (the 21066, or LCA4), and 233MHz (the 21066a, or LCA45). The 21068 chips are rare. They serve mostly as embedded controllers for realtime applications. The 21066 and 21066a processors received wider distribution. Digital shipped them as part of two motherboard packages: the AXPpci33 motherboard (which became known as the Noname board because Digital never gave it a code name), and the Multia Universal Desktop Box (also known as the Multia or the UDB). When they first came out in 1994, LCA systems were more expensive than most PCs, primarily because of the large quantity of software tools that came with the systems. Now that their prices are low, these units
have become popular among hobbyists.
The Original Consumer Alpha
Digital introduced the 21064 microprocessor in a series of systems that
don't run NT. DEC 3000, 4000, and 7000 AXP servers and workstations, which
Digital based on the TURBOchannel or Futurebus for I/O support, can't run NT. The later AlphaStation and AlphaServer systems, which Digital based on the PCI bus, were the first Alpha systems Digital designed with NT in mind.
The 21064 has a dual-issue architecture with an external bus as wide as 128 bits. The 21064's data and instruction Level 1 caches are 8KB each. The 21064a has as much as 16KB each of Level 1 data and instruction cache. The 21064 came in frequencies ranging from 100MHz to 300MHz, and it was the first chip in The Guinness Book of World Records. In 1992, the chip set a record as the fastest microprocessor available. The 21064 is no longer the fastest CPU, but it still performs respectably; its floating-point performance rivals that of some current x86 platforms.
The 21064 was available on a variety of motherboards and in a variety of
systems. Digital's 21064 systems include the Alpha XL minitower PC; the
AlphaStation 200, 250, 255, and 400 workstations; and the AlphaServer 1000, 2000, and 2100 servers. All these machines run NT and other OSs, including OpenVMS, Linux, and Digital UNIX. Digital manufactured the EB64 and PC64 motherboards for OEMs to use to build 21064 systems. OEMs used the EB64 primarily for design planning and the PC64 for production of Alpha system clones. PC64 motherboards support processors ranging in speed from 233MHz to 300MHz, cache ranging in size from 512KB to 2MB, and as much as 512MB of 128-bit RAM. The PC64 uses a baby AT form factor and provides three dedicated PCI slots, two ISA slots, and one shared PCI/ISA slot for I/O.
The oddest NT-capable 21064 system is the DECpc AXP150 (also known as the
DEC 2000 Model 300 or 500 and by its code name, Jensen). When Digital began
shipping this 100-percent EISA box in 1993, it was the first Alpha system to run
NT, and it turned out to be the only non-PCI Alpha system to run NT. The DECpc
AXP150 CPU runs at 150MHz. Digital had to slow the processor from its original
design specification of 151.5MHz to meet supercomputer export restrictions of
the time. The system was as fast as modern 90MHz-to-100MHz Pentium machines at a
time when Intel was just announcing the 60MHz and 66MHz Pentium chips. The DECpc
AXP150 has eight SIMM slots for as much as 128MB of RAM interleaved in two banks
of four SIMMs each. The system offers few expansion options because it lacks a
PCI bus and the processor is not upgradable. The DECpc AXP150's NT hardware
abstraction layer (HAL) is too complex to warrant updating this Pentium-class
performer to Win2K.
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