What is in a clock speed?   Confined to Intel processors alone, a higher clock speed generally means faster performance.  Add AMD processors to the scene, and things become a little more complicated, at lower clock speeds an AMD processor has the potential to actually perform faster than an Intel processor, and vise versa.  Allow Cyrix to contribute to the comparison, and the microprocessor world quickly becomes a frightening place to explore, especially for those of you looking to purchase a new system.

There is a new competitor to the desktop market, the Digital Alpha 21164PC.  What makes the 21164PC so unique is that it isn't backed by the marketing hype the Pentium II has been blessed with, and it definitely doesn't have the strong foundation in the Desktop PC market that AMD and Cyrix have established, rather, the 21164PC is sporting a feature comparable to no other desktop processor out today, a 533MHz clock rate.

While it is architecturally much more advanced than, say, the AMD K6, the 21164PC's marketing strength lies in its clock rate to those that aren't familiar with the Digital Alpha processors.  If a user is looking to purchase a new computer, would he/she rather go for a 333MHz Pentium II...or a 533MHz Digital Alpha Workstation if they were priced within $100 of each other?  Naturally, its human nature to want more, and since "bigger is better" the 533MHz Alpha would be the perfect choice, right?  Wrong.

Does this mean that the Digital Alpha 21164PC processor is a piece of junk?  Absolutely not, like any product in the Hardware World, it depends on what type of user you are, and what you're looking to get out of your system.  Anand Tech managed to arrange a review of a custom made Digital Alpha 21164PC based system, by Multiwave Direct, an online vendor located in California.  Let's take a look at the specs for the MWave System...

The Multiwave Direct Digital Alpha System reviewed here was a mid-range setup, ideal for comparison to a mid-range Pentium II system, here are the specifications for the system:

Looking at the Multiwave Alpha System from a distance, one would assume that it is no different than a Clone Pentium II system, the 1.44 Floppy, 24X CD-ROM drive, and AOpen Mid Tower case provide for an excellent disguise for the Digital Alpha powerhouse CPU found under the hood. Removing the case of the MWave system wasn't a problem at all, 4 standard sized Phillips head screws on the back of the case held the external housing in place, by removing those four the outer casing slid off from the back, a piece of cake.

The interior of the Alpha system was much like any normal ATX system, unfortunately the AT/ATX combination design of the AOpen case was a bit cramped for a Mid Tower case.  The ATX form factor Digital 164SX motherboard fit snugly into the case, however it positioned the 21164PC's massive heatsink in the way of one of the 2 internal hidden Hard Drive bays, rendering that bay unusable.  The close proximity of the Western Digital 4.3GB Ultra ATA drive to the Alpha's Heatsink/Fan combo may leave you with a sense of uncertainty about the system's assembly, however in the tests conducted the system didn't exhibit any problems because of this.  The path directly above the 21164PC's fan was left unobstructed for the most part, keeping the processor fairly cool.

While running the ambient case temperature didn't seem to be any different than the Pentium II - 333 system it was pit against, however the design of the motherboard placed the 21164PC's 413-pin Socket in a conventional AT motherboard position, instead of in the path of the Power Supply's fan which makes cooling this system a little larger task than you would expect from a "ATX" System.  It would have been nice if Digital had conformed to the ATX 2.1 specification with the design of their 164SX motherboard, but you can't always get everything you wish for.

The motherboard tested with the 21164PC, as mentioned above,  was a Digital 164SX motherboard, the motherboard features a total of 4 PCI slots and 2 ISA (none shared) with two of the 4 PCI slots featuring the extended connector to support 64-bit PCI cards such as high end graphics adapters (current Socket-7/Slot-1 systems use 32-bit PCI slots).  Any of the four slots can be populated by 32-bit PCI cards, there is no performance increase achieved by running a 32-bit PCI card in a 64-bit slot since both slots operate at 33MHz, however a "true" 64-bit PCI card, one that has the extension on the card, can only be installed in a 64-bit PCI slot.

The 4 PCI slots are divided into a pair of standard 32-bit PCI slots, and another pair of 64-bit PCI slots that can accept both 32-bit and 64-bit PCI cards.  The system came shipped with a Matrox Millennium II in one of the PCI slots, however the Millennium II isn't available as a 64-bit card, for that you must divert your attention to some more expensive solutions, particularly ones based on 3DLabs' high end chipsets.  The other device occupying a PCI slot was the PCI Network Interface card, a standard 100Mbps Network card making this Alpha System ideal for use on a network.

One of the two ISA slots (none of which are shared) received the attention of the Creative Labs Sound Blaster AWE64 Value Edition card which came standard with the MWave System, although the Alpha isn't much of a gaming platform it is nice to know that you don't lose any of the fringe benefits x86 PC users take for granted with the Alpha. 

The 164SX, based on the Digital Semiconductor 21174 Chipset, uses 4 DIMM slots that can accept SDRAM DIMMs in sizes from 16MB to 128MB, the catch here is that the SDRAM must be installed in pairs.   In Socket-7 and Slot-1 systems, to equal the 64-bit memory data bus a single 64-bit wide DIMM can be installed with no problems what-so-ever, however Alpha systems feature a much wider 128-bit data path to the memory, requiring the use of 2 64-bit DIMMs to equal the width of the data bus (2 x 64-bits = 128-bit data bus).  Don't think that Multiwave chose to skimp on the RAM on their mid-level Alpha system, the requirements for SDRAM on the 164SX are very strict, comparable to the PC100 Specification by Intel.  The system which was tested here used 2 x 32MB 10ns - 100MHz Viking SDRAM DIMMs, very high quality memory.   For the purpose of making the tests even between the two systems compared here the Viking DIMMs were replaced by two 64MB Advanced Megatrends 10ns 100MHz SDRAM DIMMs which worked perfectly in both the Alpha and the Pentium II systems.

Surprisingly enough, the ATX form factor 164SX features an on-board Cypress CY82C693U controller chip that supports two EIDE channels, a keyboard, mouse, as well as a PCI-to-ISA bridge all in one unit...no SCSI for this system, the 21164PC is obviously a processor for those looking for outstanding performance at a degraded cost.  The Western Digital Caviar was installed on the Primary IDE channel found on the 164SX motherboard, with the AOpen 24X CD-ROM drive configured as a master on the Secondary Channel. 

The floppy disk controller is a standard National Semiconductor Super I/O, similar controllers can be found on nearly any standard PC motherboard.  The once foreign Digital Alpha world is now beginning to look a lot like the standard x86 realm...that was Digital's plan from day one, and it is quite apparent in the 21164PC.

Taking a closer look at the design of the AOpen HX-45 case the Multiwave Alpha's 164SX motherboard was removed, to reveal the tray it was sturdily installed on.  AOpen chose to differentiate the AT and ATX stand-off holes from each other by marking them with either an A, B or A/B for combination holes based on the individual specifications.  While it will be difficult to come across another Digital Alpha motherboard in the mainstream market, if you ever do decide to drop the Alpha platform you can rest assured that the Multiwave Digital Alpha system is completely upgradable to an x86 processor/motherboard.  For the sake of keeping the tests uniform, a Pentium II + AOpen AX6L combination was installed in the AOpen case for the Pentium II tests.

The 235W power supply in the case does a fair job of powering all of the devices in the case upon receiving it from Multiwave, however if you add a few more demanding peripherals in there (10,000RPM Hard Drives, etc...) you may want to consider a larger unit, ideally a 300W upgrade but a 250W minimum.  The power supply itself has 6 power connectors sprouting out of it, 4 - 5 pin HDD style connectors and 2 - smaller floppy drive style connectors.  From the warehouse, two of those 4 HDD connectors are already used up by the Western Digital drive and the AOpen CD-ROM drive, the Mitsumi Floppy drive takes up one of the two FDD PS connectors.

As you may be able to guess, at 533MHz the 21164PC does produce a considerable amount of heat, in order to dissipate this heat the 21164PC is packaged with a large heatsink/fan combo.  Installing this combo requires a bit more than a simple attachment of two clips to the socket, luckily Multiwave will take care of this procedure at their warehouse.  In order to install the heatsink, you must first place a thin thermal pad on the 21164PC processor itself (takes the place of the Thermal Compound used with most Socket-7 Heatsinks).

Secondly you must remove the fan which is attached to the heatsink via 4 screws, and place the heatsink on top of the 21164PC allowing the 2 threaded cylinders atop the processor to pass through the corresponding holes in the heatsink.  Using the 2 supplied nuts and 3/8" ratchet driver you must securely clamp the heatsink onto the processor, a torque wrench does help however it isn't necessary, just make sure you don't over-tighten.  After clamping the heatsink securely onto the processor all that is left is to replace the 4 screws to reattach the fan, and plug the fan into the motherboard via the 3-pin connector.

Configuring the motherboard for use with a Digital Alpha processor is probably an easier task than installing the heatsink.  The 164SX can be completely configured by the use of a set of 8-dip switches, three of which control the actual Bus Speed/Clock Multiplier, the user's manual documents two settings (400MHz and 533MHz) however it states that all other combinations are reserved.  All tests show than the 21164PC is a completely unoverclockable CPU, and is locked at the processor speed it is shipped at.  

The last dip switch on the set of 8 that configure the 164SX enables/disables the Fail Safe booter, which is essentially a back-up BIOS if anything were to happen to the AlphaBIOS.  Normally if you corrupt the BIOS (Basic Input Output System) of a system by either causing physical harm to the firmware, or by improperly reprogramming it, the only option you have remaining is to re-program the BIOS using specialized equipment, or by manually replacing the BIOS chip (there is another more unconventional method requiring you to hot-swap an identical BIOS on a running system with the dead chip and then reflashing the dead BIOS, however this approach is quite dangerous and I do not recommend it to anyone that hasn't done it before).  The Fail Safe booter setting, when enabled, allows you to boot from a secondary image of the firmware, at which point you can re-install an image of your BIOS from a floppy disk, not a bad idea. 

Multiwave ships all of their Alpha systems with a copy of Windows NT 4.0 Workstation pre-loaded, however in the tests conducted by Anand Tech the software was installed on the cleanly formatted Western Digital 4.3GB drive, divided into a 2.1GB NTFS Boot Partition, and a 2.0GB FAT16 Data Partition.

Unlike the conventional PC, you can't just use a bootable floppy to install Windows NT on an Alpha...for an Alpha doesn't support the conventional MSDOS boot disks that everyone seems to have laying around the house.   The ingenious solution Digital came up with was including an option to launch Windows NT setup from the BIOS (Basic Input Output System), more specifically, the Alpha BIOS you'll find on all DEC Alpha motherboards does have an option to Install Windows NT.  

Entering the Alpha BIOS of the 164SX motherboard required nothing more than a single strike of the F2 key, unlike conventional x86 BIOSes the Alpha BIOS must initialize and detect all SCSI peripherals before proceeding onto entering the BIOS Setup if the user hits the F2 key.  This can get quite annoying if you have a number of IDE/SCSI devices installed that take long periods of time to initialize, the biggest culprits being CD-ROM drives with IDE/SCSI Hard Drives initializing fairly quickly. 

The Operating System used in the Alpha benchmarks was Windows NT...why not Digital UNIX?  The 21164 (commonly found in 333, 400, 433, and 500MHz parts) and newer 21264 processors were originally designed for outstanding performance in a true 64-bit OS, Digital UNIX being the primary candidate.   However by equipping the 164 and 264 series with the ability to run x86 applications with the aid of a Binary x86 Translator (FX!32) Digital managed to boast an extremely high satisfaction rate with those looking to run high end applications/servers using Digital UNIX while also maintaining compatibility with the x86 world and Windows NT.  The 21164PC on the other hand, wasn't designed solely for use with Digital UNIX, in fact it wasn't designed for use with Digital UNIX at all.  Instead, the Windows NT market became the target of the 21164PC, a market where Intel had ruled fairly dominantly among high end home/business users for quite some time...until the introduction of the low-cost PC powerhouse, the 21164PC from Digital.x`

If Windows NT is an x86 Operating System how can it run on an Alpha?  On the Windows NT 4.0 CD are the installation files for both i386 systems (Intel 386 and above processors, the reason for choosing the 386 as the cutoff mark for backwards compatibility is because the 386 was the first 32-bit Intel processor, since NT is a 32-bit OS it cannot run on anything below that i.e. the 16-bit Intel 286 processor) and Alpha systems, the '\Alpha' directory on the NT4 CD contains the Alpha port of Windows NT 4.0, the OS itself doesn't have to be emulated in order to run on the Alpha platform. 

The applications you may want to run under Windows NT however, may not all have specific ports for the Alpha platform, in reality, a great deal of NT applications have yet to be ported to the Alpha.  With a few thousand applications native to the 64-bit RISC Alpha platform one would expect the most frequently used business applications to have alpha counterparts, however you must realize that the Alpha processor hasn't been an option in the Business Application world until now.

Previously the alpha was used in high end engineering, development, and other such situations, more recently the Digital Alpha 21164 processor was used in the making of the hit movie Titanic (note the use of the 21164 over the inferior 21164PC).   In lieu of this,Digital went to development on an algorithm that would effectively translate x86 instructions into RISC operations with a manageable and expected decrease in performance.  The result of Digital's efforts was a software product dubbed FX!32.

Getting all of the setup and configuration out of the way was the difficult part, from that point on, using the Multiwave Alpha System was no different than your run of the mill Windows NT PC workstation.

No software came pre-installed with the Alpha system so there wasn't much of anything to play around with, but Windows NT acted and performed just as it would if one were running it on a x86 system. 

After downloading and installing the latest version of Digital's Binary x86 Translator, FX!32, a new icon appeared both on the desktop and in the systray.  Double clicking the Install x86 Application icon launched the FX!32 installer which quickly took me through the process of installing the first copy of any x86 program on the test system, Ziff Davis' Winbench 98.  The installation went quite smoothly, although a bit on the sluggish side at first while copying data to the hard drive, the setup procedure continued without a hiccup, never did the Setup software crash or exhibit any out of the ordinary behavior because of the nature of the platform it was being installed on. 

A few more installs of other applications ranging from Microsoft Office 97, Adobe Photoshop, and Truespace 3.0 truly revealed how simple it is to make use of Digital's outstanding Binary x86 translator, however this was only the beginning.  Simply being able to install an x86 application is only a fraction of the beauty of FX!32, by using the FX!32 manager you can optimize x86 applications over and over again until you approach a level of performance closer to full speed although not nearly to that point as of now.  Most applications took three or four runs in order to get the Alpha system to begin to launch and work with them to a certain level of efficiency.  Let it be noted that not all x86 applications will work with FX!32 v1.2, Microsoft Frontpage 98 for example will not install on an Alpha system, the engineers at Digital are still working on a fix (Frontpage 97 does work on the other hand). 

Microsoft Office 97 was probably the best example of how well an Alpha system can run x86 code, all of the applications in the Office 97 Professional Suite performed as if they were running on a Pentium II system, with no noticeable differences between a Pentium II - 333 system and the Alpha, however the Alpha obviously didn't outperform the Pentium II - 333 in any of the Business Office 97 tasks that were experimented with.  As time goes on, and as future revisions to the FX!32 software are made the Alpha platform will slowly become a threat to Intel's throne under Windows NT, but for now, it is simply a lesser if not equal alternative.

Adobe Photoshop ran fairly well on the Alpha system, converting a large 10MB JPEG file from a 1280 x 1024 resolution to a more manageable 640 x 480 took approximately 20 - 45% longer to do on the Alpha than the Pentium II - 333 test system took, even after Photoshop was optimized using FX!32 numerous times.   Performing various filters on the image once again left the Pentium II as the champ, it is quite obvious that the high speed L2 cache of the Pentium II (in this case operating at 187.5MHz) really benefits the system's performance under Windows NT.   Some of the more expensive Alpha processors, like the 21164 or the 21264 with on-chip L2 cache should perform much better under Windows NT however that eliminates the price point comparison between the Alpha and the Pentium II system.

The question was raised as to why the tests only included Windows NT as a benchmarking platform, naturally this is unfair to the 64-bit 21164PC and quite biased towards the Intel Pentium II, however the 21164PC and the Digital 164SX Motherboard were both specifically designed for use under Windows NT.   The 164SX manual even specifies that it is a Windows NT motherboard, there are Alpha systems designed to run under Digital Unix which are available on the market, however their price reflects their outstanding performance as well.

All Business Graphics Tests were run at 800 x 600 x 8 bit color
All High End Graphics Tests were run at 1024 x 769 x 16 bit color

Winstone 98/97 would not complete a successful test run on the Alpha platform and therefore weren't used.

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The Pentium II & MWave Digital Alpha systems were configured identically, the Alpha Port of Quake 2 was used for the Quake 2 x86 Gaming Performance Tests.

 

 

 

 

DEC Alpha 21164PC Features

• 24KB of on-chip L1 Cache (16-KB Instruction + 8KB Data)

• 512KB - 4MB of off-chip L2 Cache

• 128-bit Memory Data Path

• 138mm² Die Size

• 3.4 Million Transistors

• 413-pin Ceramic PGA Packaging (for use with 413-Socket Motherboards)

• 50mm x 50mm Package Size

Technical Features

• 2-Integer and 2-Floating Point Instruction Issue Rate

• 7-stage Integer Pipeline

• 9-stage Floating Point Pipeline

• 128-bit Bus Width

• 4-Way Superscalar Instruction Issue

RISC vs CISC

First of all, the DEC Alpha, unlike x86 processors, is a RISC Processor or a processor that accepts and processes Reduced Instruction Sets hence the name Reduced Instruction Set Computing (RISC).   More familiar to all of you would be the x86 processor, like the 486, Pentium, Pentium MMX, Pentium II, K6, 6x86MX etc..., all of those processors in contrast are CISC Processors, or processors that accept and process Complex Instruction Sets hence the name Complex Instruction Set Computing (CISC). 

Bridging the Gap

Bridging the gap between RISC and CISC processors is quite difficult, in some cases CISC processors prevail and in others RISC processors rule the kingdom.  Is comparing a 533MHz DEC Alpha to a 333MHz Pentium II fair?  Actually, yes.  The Alpha processor achieves its immense speed through the use of extremely high clock speeds, as with all Alpha processors, underclocking them to the levels of their Intel competitors is quite unfair to the Alpha processor since the processor itself was never designed to run at clock speeds that low.  One of the benefits of RISC architecture is the ability to achieve those high clock speeds, ever wonder why the industry is moving towards a non-CISC standard?  Although CISC chips are extremely fast at lower clock speeds, pushing them up to clock speeds 1.5 and 2x those we are at now is slowly becoming much more difficult due to limitations of the architecture.  That's why some of the current x86 processors out today do feature some RISC-like qualities, such as the Intel Pentium II and the AMD K6, the AMD K6 for example features a RISC86 decoder which converts the Complex Instructions it receives into easy to manage Reduced Instructions.

The 21164 and its PC Brother

Now lets talk about the Alpha you'll be seeing much more of here, the 21164PC.  You may be wondering why the Alpha is mentioned very infrequently as being a competitor to the Pentium II, AMD K6, etc..., that is because until now, Alpha systems have simply been too expensive for most "High End - Home Users" to purchase.  What made the Alpha so much more expensive than x86 systems?

Remember the Pentium Pro?  It was essentially a more advanced Pentium processor, with 256KB - 512KB (now even up to 1MB) of L2 cache on the chip itself running, and here's the keyword, *at* clock speed.   Meaning a 200MHz Pentium Pro had 16KB of L1 cache running at 200MHz in addition to 512KB of L2 cache running at 200MHz.  For those of you that aren't too familiar with the functions of L1 and L2 cache, Cache is essentially a small amount of high speed RAM that serves as a mid-way point between your CPU and Memory.  It stores frequently accessed data for future use, since in the case of the Pentium Pro, the L1 and L2 cache is located on chip there are no Bus Lines to traverse to access the Cache and therefore data extracted from the Cache can be performed at a much faster rate than data from the System Memory.  In the same case of that 200MHz Pentium Pro, the System Memory would be running at a 66MHz bus speed, while the Cache operates at 200MHz...about 3x as fast.   The one downside to placing both the L1 and L2 cache on chip was that it significantly raised the price of the processor, and as you might be able to guess Digital's fastest Alpha chips were also plagued by this hefty price-tag. 

Digital's solution?  Kick the L2 cache off the chip, pump up the clock rate, and provide a low-cost alternative Alpha chip for the High End Home/Office Market that could compete directly with the Pentium II.  This they did, and the result was the original 21164 Alpha, with the letters 'PC' tacked on to the end of it...the 21164PC.

* Unofficially Achieved Bus Speed - this processor is capable of running at the 100MHz Bus Speed

The Digital Alpha is by no means intended to be a Home Computing system, while it is still very competitive with the Pentium II in performance, it lags behind in compatibility with x86 applications. The user base of the Alpha platform is growing rapidly, and Multiwave has proved to the world that it isn't difficult to make a down right decent system out of just about any processor, unfortunately this Multiwave System won't be finding its way into the homes of many average PC users.

Those that need the power of an Alpha will most likely stick to the more professional models, like the 21164 or the newly released 21264, the 21164PC was a nice try at the Desktop x86 market, unfortunately it was a failed attempt by Digital to gain a portion of the Intel pie.