The Computer Guys

Miami to Fort Lauderdale Since 1994

 

 

We Build the Best & Repair the Rest! ©

 

 

HardWare 101

FAQ Search Virus Alerts Hardware Faqs

 

 

Computer Repair
PC Maintenance
Disaster Recovery
SpyWare Removal
Company Profile
Disclaimer
Contact Information
Home Users

 

Here you will find some basics, it is by no means complete. 
 

 

Hardware 101 - Quick Jump

  1. Belarc Advisor - Free Personal PC Audit (version 6.1f)
  2. Chipsets 101  
  3. The Intel 440BX AGPset  
  4. Universal Serial Bus (USB)  
  5. Sockets versus Slots  
  6. The World of DVD   
  7. Firewire IEEE-1394  
  8. Bandwidth: The Need For Speed  
  9. The Future of Network Bandwidth  
  10. The History and Future of Storage  
  11. A Introduction to AGP  
  12. AMD K6-2 and 3D Now!  
  13. Moving Beyond SDRAM  
  14. Intel 440GX AGPset & 450NX PCIset  
  15. Intel Pentium II Xeon Processor  
  16. Inside Intel's Celeron(tm)/333A
  17. RAID Explained
Chipsets 101
If the processor is the brain of a system, then the chipset is the heart of a system. In the past, third-party vendors (OPTi, VIA, SiS, etc) created the chipset for Intel-based processors. Today, Intel dominates the chipset market, while other vendors are constantly playing catch up with Intel.

Click here for a complete listing of each chipsets' features and specifications.

Notice that Intel chipsets are at the 100MHz bus, Pentium II class, while other vendors are mostly doing the socket 7 class. This is not by design; the slot 1 architecture is patented and heavily protected by Intel.

The Intel 440BX AGPset
The 440BX AGPset is the third generation Pentium II class chipset from Intel. (The first and second generation being the 440FX PCIset and 440LX AGPset, respectively.) Along with support for SDRAM (up to 1GB), AGP 2x at 133MHz, and UltraDMA/33, the 440BX is the first chipset to support 100MHz memory bus speed. Pentium II CPUs from 350MHz to 400MHz (currently) will be able to run at 100MHz memory bus speed. One practical advantage of the 100MHz memory bus is that all processor speeds, starting with 350MHz, will be increments of 50. CPU speeds such as 233, 266, 333, etc. will be gone forever. Now we can have easy to remember numbers such as 350, 400, 450, etc.

The increase from 66MHz to 100MHz memory bus will definitely help overall system performance as CPU speeds are increasing by 50MHz almost every four or five months now. There's a limitation in CPU speed in which the memory bus becomes the bottleneck. Running the memory bus at 100MHz requires a new type of SDRAM DIMM called PC100; typically, PC100 SDRAMs are rated at 8ns or faster.

The BX also have a new feature called Open Page Architecture (OPA). This allows the Pentium II processor to leave "tabs" on virtual memory page addresses. So instead of wasting valuable CPU cycles looking for a specific memory page, OPA will allow the CPU to index the page immediately. Intel claims this will net a 3-5% performance improvement for graphics intensive applications.

Initially, the BX will be paired with the Intel PIIX4-E I/O controller. (The PIIX4-E controller governs the system memory and I/O such as the two USB ports and the UltraDMA/33 IDE ports.) Later on, this will be changed to the PIIX6 controller, which will add support for Firewire or IEEE 1394 and four USB ports.

Click here for the block diagram of the 440BX AGPset.

Universal Serial Bus (USB)
Universal Serial Bus (USB) is an initiative originally proposed by Intel, Compaq, and Microsoft back in 1995. The primary purpose of USB was to make adding devices and peripherals to the PC easier. And to centralized all the I/O connectors in the back of a typical PC. Currently, there are connectors for keyboard, mouse, printer, joystick, serial ports, etc. Why not just have one universal connector in which user can connect all their devices?

In addition to standardizing on one port, the USB design also have the following advantages:

Speed - The maximum bandwidth of USB is 12Mbps, which is faster than most ethernet cards. Compare this to the maximum speed of a typical serial port, which is 115Kbps.

  • Hot Swap - USB is mainly designed for external devices. Wouldn't it be nice to add and sremove devices to your system without having to power it off and on? USB allows user to add a device while the system is turned on; USB will then automatically enumerate the new device, load the driver, and allow the user to use it.
  • Flexibility - With traditional serial ports, users were limited to the type of device they can add. With USB, there's almost no limitation. A USB device may be almost anything: mouse, joystick, modem, printer, scanner, etc. Also, a user can add up to 127 USB devices per system. Of course, practical limitations may reduce this number, but it is still better than having the standard "two serial ports per system."

    So you're thinking, "Hey, this is a great idea! But if USB was introduced in 1995, where are all those wonderful USB devices today?" USB suffers from the classic chicken-and-egg problem. Peripheral makers were waiting for system manufacturers to integrate the USB port into their system, and PC makers were waiting for peripheral designers to create USB devices first. And to compound the problem, Microsoft didn't release USB drivers for Windows 95 until late 1997. If you've purchased a new computer system in late 1997 or now, chances are you'll have two USB ports with the USB drivers loaded.

    USB devices should take off once Windows 98 hits the market. For more information about USB, see the following links:

Sockets versus Slots
Pentium class processors (including AMD K5/K6 and Cyrix M1/M2) are paired with socket 7 motherboard. Likewise, Intel's IA-32 family of CPU is paired with motherboard with slot 1. The slot 1 design was conceived by Intel to make changing/upgrading the CPU easily. Instead of inserting the processor into a socket, the user simply add the CPU as he or she would an add-on card.

The socket 7 that exists on Pentium class system boards today is able to accept Intel Pentium MMX, AMD K5/K6, and Cyrix M1/M2 CPU. In the next few months, AMD introduce a new super socket 7 (or super 7) for their AMD K6-2 processor. Super 7 will allow the system board to run at 100MHz memory bus speed. This is necessary for AMD to keep up with Intel's faster IA-32 family.

As far as Intel is concerned, the socket 7 design is a dead-end. They will be focusing on slot 1 and slot 2. Because the slot 1 design is patented solely by Intel, the only company that's able to make slot 1 CPU is Intel. AMD may attempt to physically clone the slot 1 design with their next generation K7, but the electrical characteristics will be patterned after Digital's Alpha processor. For the high-end Xeon CPUs, Intel will introduce the slot 2. Physically, the slot 2 will be the same as slot 1, but the number of pins on the slot 2 will be greater; this is to accomodate the complexity of the Xeon processor.

And as a transition to the Merced, Intel may introduce yet another slot called slot M in 1999.

The Multimedia World of DVD 
Current CD-ROM discs are able to storage a maximum of 640MB. DVD, the successor to CD-ROM, discs are able to store up to 4.7GB of information! And that's just the beginning. Using dual layer technology, the storage capacity will double to 9.4GB per disc. In addition, information may be encoded on both side of the DVD disc, giving us an incredible 18GB per DVD in the near future.

So what can we do with 4.7GB of information? We can put a full-length movie (2+ hours) encoded in MPEG2 format with Dobly Digital 5:1 (or AC-3) on a single 4.7GB DVD disc today with room to spare! Because of the extra free space, most DVD titles comes with different language tracks: English, Spanish, French, etc. A little known fact about DVD is that it really doesn't stand for anything, but people have associated DVD as Digital Video Disc.

MPEG2 is a processor intensive compression / decompression scheme; click here to learn more about MPEG2 decoding. The visual quality of a typical DVD movie is much sharper and better than super VHS or even a laser disc. Unfortunately, quality comes with a price: an Intel Pentium II/333 or faster processor is required in order to perform software MPEG2 decoding. Because of this, most PC DVD kits rely on a dedicated MPEG2 decoder PCI card. Due to current technology, this is an inexpensive solution since it frees up processor for other use.

In addition to the high quality visual aspect of DVD, it also incorporates Dobly Digital 5:1 or AC-3. This is an audio encoding scheme developed by Dobly Labs. Click here for more details.

Firewire IEEE-1394
Let's take a closer look at a faster version of USB, dubbed Firewire or IEEE-1394.

Firewire will have all the benefits of USB, including more bandwidth. The maximum bandwidth of USB is 12Mbps (1.5MB/sec); Firewire's initial speed will be 200Mbps (25MB/sec), which will be increased to 1Gbps in the future. But Firewire will not replace USB; in fact, it is designed to be a supplement to USB. Low speed devices (such as keyboard, mouse, joystick, etc) will be connected to the USB port. While high speed, bandwidth-demanding devices (such as digital camcorder, CD burner, etc) will be attached to the Firewire bus. 

And like USB, Firewire hasn't really taken off yet. Currently, the only mainstream manufacturer of Firewire host controller is Adaptec. The primary function of Firewire today is digital video editing. Sony, Panasonic, and other camcorder makers already have Firewire-enabled camcorders available today. In addition, Firewire may eventually replace IDE as the primary interface for consumer-level hard disk drives. The current IDE interface is limited to four devices on two channels (primary and secondary), with a maximum cable length of about 12 inches per channel. Firewire is limited to 64 devices with a cable length of 13.5 feet between each devices

Bandwidth: The Need For Speed
One of the main factor that's preventing the Internet from become an all pervasive tool is bandwidth, or the lack of it.

If you're a casual user who uses the Internet for work and play, then you'd wish that website would load just a bit faster. And if you're a hardcore user who basically spends eight or more hours per day on the net, then you can never have enough bandwidth! New technologies on the horizon promise to alleviate the bandwidth bottleneck for consumers. The bad news is, they are not widely available yet. Here's a quick rundown on each of them (starting with the slowest):

POTS Modems - POTS stands for plain old telephone system; most households today probably have two or more phone lines. Modem technology have increased dramatically over the past few years. Consumers have witnessed the increase from 14.4K to 28.8K to 33.6K to today's standard of 56K. Today's copper phone wires are limited to 53K due to an existing FCC regulation. This is about as fast as you can push it with POTS modems. And even with 56K technology, depending on where you are, your speed may vary from 38K - 52K. Even with these limitations, a POTS modem is still the most cost-effective solution for the majority.

  • Multilink - So if you have two phone lines at home, wouldn't it be great if you can somehow link those together and double your bandwidth with POTS modem? You can with the multilink feature that's available in Windows 98. Multilink allows you to bond two (or more) modems to create a single data channel. For example, if you have two 56K modems and your connection speed for each is 44K, then your overall bandwidth is 88K. A few things to keep in mind though. You'll need two different phone lines, and your Internet Service Provider (ISP) also have to support multilink. And most ISPs will charge you double for using this feature. Also, keep in mind that multilink will use the slowest speed of the modem. It doesn't make sense to multilink two 14.4K modems (for a total of 28.8K), when you can use a single 56K modem instead.
  • ISDN - Integrated Service Digital Network never really caught on for a few reasons. ISDN's bandwidth is 128Kbps using two 64K D channels. ISDN is still not widely available; the setup cost and usage of ISDN is relatively high compared to POTS modems.
  • Satellite - Satellite's bandwidth is around 400Kbps. This is more than enough for most users. But the setup fee of a satellite connection is high, and this technology isn't widely available yet. But if you need the speed and can afford it, then it's a good alternative to POTS modems.
  • ADSL - Asymmetrical Digital Subscribe Lines is one of the technology to watch for in coming years. The downstream bandwidth is 8Mbps. Both Intel and Microsoft have recently jumped on the ADSL bandwagon. The monthly fee isn't very high, but ADSL's availability is very limited right now.
  • Cable Modems - The Holy Grail for all home Internet users today. Cable modem's downstream is an incredible 30Mbps. The monthly cost is around $40 for unlimited usage. (You must have cable for TV in order to use cable modem; so the $40 charge is in addition to your monthly TV cable bill.) Consider yourself lucky if your neighborhood offers cable modem today. It is being deployed in some major metropolitan US cities.

    To give you an idea how fast cable modem is, most businesses are running with fractional T1 (from 256K to 1.5Mbps) or a full 1.5Mbps T1 line. 1.5Mbps is for the entire office consisting of, depending on the size of the business, perhaps 30-40 users. Larger corporations with a DS3 or T3 connection have a bandwidth of 45Mbps.

    Of course, cable modem's 30Mbps bandwidth is only achieveable if you're the only person using it. Most often this is not the case, as the entire neighborhood shares the 30Mbps bandwidth. But even if it delivers only 1.5Mbps, it's still more than enough for a single user.

The Future of Network Bandwidth
Many businesses today are still using 10Mbps ethernet as their primary network connection between desktop computers and hubs. But new companies are starting out with 100Mbps fast ethernet connections for every segment of their network: desktop, hub, backbone, etc. With the explosive growth of the Internet, it seems that we can never have enough bandwidth to satisfy our needs. Transfering multiple video streams will even bring 100Mbps LAN to its knees.

As such, there are always newer and faster networking technologies that promise to deliver more bandwidth. Here's a quick summary of each technology:

Type Speed Pros Cons Available?
Ethernet 10Mbps or 1.25MB/sec Inexpensive Showing its age now Everywhere
Fast Ethernet 100Mbps or 12.5MB/sec Fast Hubs are still expensive Everywhere
Gigabit Ethernet 1,00Mbps or 125MB/sec Extremely Fast Still an emerging technology; expensive Limited
Fast Gigabit Ethernet 10Gbps or 1.25GB/sec Smoking! Being developed No
Fiber Optic or FDDI Up to 100MB/sec Fast and long distance Very expensive Limited
ATM 25Mbps to 655Mbps Fast and quality of service Expensive Limited

ATM is the only technology that has quality of service (QOS). This means if a video stream requires x amount of bandwidth, ATM will guarantee x amount of bandwidth. Fast Gigabit Ethernet is still in the development stage now, and probably won't be out until late 1999. FDDI and ATM is still too expensive for every single desktop systems. The fastest and cost-effective solution today is Fast Ethernet. Fast Ethernet network adapters are relatively inexpensive now; the biggest investment is still probably the hub.

The History and Future of Storage
Since the advent of computers, users have been searching for the most efficient way to store their data.

As a sidenote, the high cost of storage in the past is partly responsible for the famous (or infamous) Year 2000 problem the computer industry is facing now. In the past, data storage on magnetic media was extremely expensive. Instead of storing all four digits to represent a year, people choose to store only two digits, to save space and cost. For example, 1998 would be stored as 98 only.

Here's a summary of the storage technologies used in the past and what's coming up in the near future. This article will focus primarily on magenetic and optic media:

Floppy Disk - Like the ISA slot, the floppy disk drive is still present in most PC systems today. Even though alternatives such as Iomega ZIP and LS-120 are readily available now. The floppy drive is kept mainly for legacy reasons today; some people still have important data stored on their 3.5" 1.44MB disks. This drive probably won't be phased out until the year 2000.

Hard Disk Drive (HDD) - The primarily storage for most people today. The size of the average HDD have increased dramatically over the past five years. And the price of the average HDD have also dropped considerably. This is mainly due to advancement in magnetic media storage technology. Nothing beats HDD for storage: it's the fastest storage technology available and it's relatively cheap.

CD-ROM - The capacity of the CD-ROM (roughly 640MB) hasn't increased since its introduction. But the speed of CD-ROM drives have increased geometrically. We have seen drives that were rated for 1x, 2x, 4x, 8x, 16x, 24x, and finally stopping at 32x. Although most CD-ROM drives that claim 32x actually average about 12x to 20x. Only data stored on the outer ring of the CD-ROM disc is read by the drive at 32x. The inner rings cannot sustain 32x throughput. 1x is approximately 150K/sec. So a 32x drive is capable of reading data at 4.8MB/sec (150K/sec * 32 = 4,800K/sec). Today, CD-ROM is the most popular for software publishing to distribute their application.

Removable HDD - HDDs are nice and fast, but you can't move them from system to another easily. Removeable HDDs solve this problem. The most popular media of this type is the Iomega JAZ (1GB/2GB) drive. JAZ drives have comparable performance to normal HDDs. The LS-120 and Iomega ZIP drives also fall into this group, even though they only store 120MB and 100MB per disk, respectively. The best thing about the LS-120 is its ability to read normal 3.5" 1.44MB floppies; when LS-120 drives come down in price, it may completely replace the floppy drive.

Removable Optical Drive - This technology never really caught on in the consumer market. Optical media allows the user to write to a disc as many times as she wants. Pinnacle Mirco is the main player for optical drives. Its Apex optical drive is able to store 4.6GB on both side of a disc. But it was too expensive and too late. The JAZ drive was faster and cheaper.

CD-R - These are CD-ROM drives with the ability to record or "burn" a CD-ROM disc. A lesser known name for CD-R is CD-WORM drives (write once, read many). If you need to store data that doesn't change, then CD-R is the way to go.

CD-RW - This takes CD-R to the next logical step: CD-RW (read/writeable) is able to write to a CD disc more than once. CD-RW hasn't really caught on yet because CD-RW discs are more expensive than blank CD-R discs. And if a user wants to repeatedly write over the media, there's always tape backup drives, which is slower but much cheaper. In addition, a CD-RW disc may not be readable to a regular CD-ROM drive.

DVD-ROM - The next generation of CD-ROM drives. DVD-ROM discs can store up to approximately 4.6GB of information. (See the article "The Multimedia World of DVD" for more details.) Because of the higher density of DVD-ROM discs, the speed rating of DVD-ROM drives is different from CD-ROM drives. Most DVD-ROM drives today are rated at 2x while reading DVD discs and 20x while reading CD-ROM discs. 1x for DVD-ROM drives is about 1.5MB/sec. DVD-ROM drives should replace CD-ROM drives by the first half of 1999.

DVD-RAM - The future of optical storage is DVD-RAM. This will allow users to write to DVD discs as they would a normal HDD. Currently, there's no standard for DVD-RAM. DVD-RAM created discs may not be readable on all DVD-ROM drives. This technology probably won't take off until second half of 1999. 

With all these choices, it's easy for the average consumer to get confused. My recommendation would be, get a large IDE HDD (greater than 6.0GB in size) and a DVD-ROM drive (which can read DVD-ROM, CD-ROM, and CD-R discs). Add a CD-R drive if you're interested in creating your own music and data CDs. Don't spend the money on a CD-RW or DVD-RAM now. And finally, get a JAZ drive if you need to move large (>100MB) files around from one system to another daily. Otherwise, get a LS-120 drive, which can read normal 3.5" 1.44MB floppy disc and 120MB floppy disc.

A Introduction to AGP
With today's demanding games and multimedia applications, even the well-proven PCI bus cannot meet the video bandwidth requirements. The 32 bit PCI slot running at 66MHz have a peak bandwidth of 133MB/sec. And in most cases, the 133MB/sec is only for burst mode; the PCI slot cannot sustain 133MB/sec indefinitely.

Because of this limitation, Intel introduced the Accelerated Graphics Port (AGP) architecture for video cards. It's important to note that the AGP slot is for video cards only, unlike the multi-purpose PCI slot. AGP is just beginning to take off this year. The first Intel chipset to support AGP was their 440LX AGPset, which is now being displaced by the newer 440BX AGPset. The AGP slot is able to run at 66MHz with the LX AGPset and a full 133MHz with BX AGPset. Currently, AGP's full speed is 2x mode; Intel will increase this to 4x in the very near future.

With the AGP slot in place, games and applications are able to move and copy texture from system memory to video memory at a very high speed, a feat that wasn't possible with the PCI architecture. For now, 3D technology is known mainly in the gaming and graphics designing world. But this may change when Microsoft release their "Chrome" technology for web browser sometime in 1999. "Chrome" will move 3D graphics and animation into your browser.

For more technical information, go to the AGP Forum website.

AMD K6-2 and 3D Now!
Intel dominates the processor market with an 80% market share. By leveraging their processor and chipset advantage, no company is even close to challenging Intel. Both AMD and Cyrix have tried unsuccessfully in the past.

But with the FTC lawsuit pending against Intel, and the growing segment of sub $1,000 systems, AMD may be in a position to do some real damage to Intel's market share. It's rare that Intel would misjudge the market. But it did with the sub $1,000 market, and now Intel is trying to regain grounds with its low-cost Celeron CPU.

AMD recently launched their next generation AMD K6 processor named K6-2. The MMX instruction set in the K6-2 has been optimized so it performs about the same the Pentium II CPU. In addition, AMD has added additional MMX instructions for floating point operations; this MMX extension is named 3D Now! Current Intel MMX instruction sets only works with integer. AMD have actually managed to leapfrogged over Intel technologywise with the K6-2. And K6-2 will level the playing field by bringing the 100MHz memory bus to socket 7 motherboards.

But the K6-2 is still a socket 7 processor. (See the Sockets versus Slots for a discussion of sockets and slots.) Does the K6-2 have a chance in the market place when everything seems to be transitioning to slot 1? Yes, it does indeed have a fighting chance. Ironically, Intel has just recently announced the socket 470 for their upcoming Celeron with L2 cache processor! So the socket market is not as dead as Intel wants you to believe.

Initial benchmarks have shown that the K6-2 is very close to an equivalent Pentium II at the same clock speed. AMD won't be stopping with the K6-2. They plan to introduce the K6-3 by the end of this year. The K6-3 will have 256K of cache onboard.

Moving Beyond SDRAM
Moore's Law states that processing power will double every 18 months. And since the introduction of the Intel 8088 processor, this law has never been broken. But increasing the performance of a processor also requires increasing the bandwidth of the memory subsystem.

Here's a brief look at the past, present, and future memory technologies.

Fast Page - The standard type of memory for 486, and early Pentium 60/66/75/90 (still remember those?) systems. Back then, fast page memory was sufficient to keep up with the processor.

  • EDO - Extended Data Output. EDO delivers about 10%-15% performance increase from fast page memory. The read cycle from memory and CPU is shorten. EDO became the dominant memory when the Pentium 100/133/150/166 (non-MMX) appeared on the market.
  • SDRAM - Synchronous DRAM. With the advent of the Pentium MMX and Pentium II processors, memory technology took another leap in terms of raw speed. SDRAM coordinates the input and output of the memory and the processor. Makers of SDRAM claim a performance improvement of 50% or more over EDO memory. But in the real world, the performance is only about 20%. Currently, SDRAM is the dominant memory type, for both the 66MHz and the new 100MHz (PC100) bus.
  • SDRAM II (DDR) - Double-data rate SDRAM aims to double the performance of current SDRAM. DDR allows the processor to read from memory on both the rising and falling edge of the clock. Currently, no Intel or third party chipset fully supports DDR.
  • RDRAM - Rambus DRAM. This is based on the technology developed by Rambus, Inc. Intel have selected RDRAM for their future processors, IA-32 (Katmai) and beyond. RDRAM uses a narrow data channel clocked at extremely high speed to achieve high performance. The Nintendo 64 game console uses Rambus as its primarily memory interface.
Intel 440GX AGPset & 450NX PCIset
Intel will be officially launching its next generation Pentium II processor this month. The Xeon processor promise higher performance while maintaining Pentium II compatibility. The Xeon CPU will require a new slot 2 architecture. This means Xeon system board will using new chipsets.

440GX AGPset - The only difference between the 440GX and the current 440BX is the 440GX will be able to address up to 2GB of memory (440BX can only do 1GB). The 440GX will be able to support both the slot 1 and slot 2 architecture. Since the 440GX will only support up to two Xeon processor, this AGPset is intended for highend workstations and mid-range servers. All the features of the 440BX (100MHz FSB support, USB, UltraDMA/33, AGP 2x, etc) will be present on the 440GX. 

  • 440NX PCIset - Notice the 450NX is classified as a PCIset instead of an AGPset. This is because the 450NX does not support the AGP slot. Intel intentionally left out AGP support because the 450NX is meant for an enterprise server system board. Another interesting aspect of the 450NX is that it only supports EDO memory. The 450NX can address up to 8GB of main memory. Intel recently annouced an errata for the 450NX and their Xeon processor. Due to this errata, four way Xeon CPU systems will be delayed a couple of weeks. Intel will be releasing a software fix for this problem. 

    Both the 440GX and 450NX represent Intel's first generation Xeon/slot 2 chipset. As expected, there's not too many new features in these two chipsets. But the second and third generation slot 2 chipsets will probably have AGP Pro (AGP 4x), Firewire, and RDRAM (RAMBUS) support. Lastly, the front side bus (FSB) between the processor and memory may be increased to 133MHz.

Intel Pentium II Xeon Processor
Intel have recently launched their next generation server-class, highend workstation processor named Xeon (tm). In keeping with the Pentium II family of names, this processor's full name is Pentium II Xeon.

With the IA-64 Merced processor pushed back to late 1999 or even early 2000, the Xeon is more than a stepping stone from IA-32 to IA-64.

The first thing you'll notice about the Xeon is its sheer size. It's about twice the size of the Pentium II processor. In addition, the Xeon is mated for a slot 2 motherboard, instead of the typical Pentium II slot 1 board.

The most important change in the Xeon is the speed and size of its L2 cache. Pentium II's L2 cache runs at half the CPU clock speed and the size is fixed at 512K. The Xeon uses a special type of cache memory called CSRAM (customized SRAM) which allows it to run at full CPU clock speed. The Xeon is available with 512K, 1MB, or 2MB (450MHz or faster) of L2 cache. The Xeon is still based on the P6 architecture and the MMX instructions are still the first generation, not the new KNI (Katmai New Instructions).

Current Pentium II processors and chipsets are limited to a dual processor configuration. The Xeon is able to scale up to quad and even eight processor later. With a quad configuration, 2MB of full speed cache, and the 100MHz FSB (front size bus), the Xeon is well suited for a server or highend workstation environment.

This level of performance comes with a cost. In order Intel to boost their profit margin, they need to market and sell the Xeon as a highend processor. 

Related Links:

Inside Intel's Celeron(tm)/333A
Intel released a new addition to their Pentium II family. This low end processor is called Celeron(tm). Essentially, the Celeron is a Pentium II CPU without any L2 cache onboard. It comes with support for MMX and fits into any slot 1 system board.

But because it did not have any L2 cache, the Celeron lags in performance when compared to the AMD K6 or K6-2 or Cyrix M2. Intel launched the Celeron at 266MHz, which they quickly moved to 300Mhz. Even at 300MHz, the Celeron was no match for the lower cost AMD K6-2. Perhaps Intel released the Celeron prematurely, but they had to release a CPU that was price competitive with the AMD/Cyrix processor.

Even before Intel was putting the finishing touches on the Celeron/300, the next generation Celeron with 128K L2 cache was in the works. Intel's initial plan was to release this new Celeron in Q1/1999. But most likely due to intense competition from AMD and Cyrix, Intel will be release their Celeron/333A by the end of Q3 of this year or beginning of Q4. The "A" at the end of the clock speed will allow consumers to differentiate between the cache and non-cache version.

The important thing to note about the 128K L2 cache is it is running at full CPU speed. The L2 cache on Pentium II processors, not including the Xeon, only runs at half the CPU speed. This mean that the performance of a Celeron/333A with 128K L2 cache is almost equivalent to a Pentium II/333 with 512K L2 cache! The speed of the Celeron L2 cache makes up for its lack of size. This will allow Intel to compete at a price point similar to the AMD K6-2 and Cyrix M2.  

RAID Explained
Unlike desktop systems which use IDE disk drives as their primary storage subsystem, servers usually utilize a SCSI storage subsystem coupled with an high-end RAID controller.

A dedicated SCSI controller can lower processor utilization, which is critical in a server environment. And most servers require some sort of fault tolerance against hard drive crashes or failures.

RAID stands for Redundant Array of Inexpensive (or Independent) Disks. The concept of RAID is simple: instead of having a single large capacity hard disk (which is expensive and prone to failure), gather a collection of smaller and inexpensive disks and call it a RAID array. For fault tolerance, split the data between the drives, instead of storing all the data on one physical drive. In addition, by splitting the data across different physical drives, I/O performance may be increased.

There are different levels of RAID technology; the three most commonly used are:

RAID level 0 (striping) - Level 0 offers maximum disk I/O performance at the expense of fault tolerance. Data is stored (or striped) across the array of drives. This can greatly enhance I/O performance by reducing the latency time present in a single drive. The downside to level 0 is, if one drive fails, then all your data would be lost. Level 0 is ideal for a workstation system, which requires optimal I/O, but it's definitely not suitable in a server.

  • RAID level 1 (mirroring) - Offers excellent fault tolerance at the expense of cost. Level 1 requires two drives: a primary and the backup drive. The size of the backup drive must be at least the same size or greater than the primary drive. Any data that is written to the primary drive is also written to the backup drive. In effect, the backup drive merely sits there waiting for a potential crash on the primary drive.
  • RAID level 5 (striping with parity) - Most servers will use this RAID level. Level 5 is simliar to level 0, except, in addition to data, parity information is also striped across the RAID array drives. Parity information allows the other drives in the array to rebuild the information on the crashed drive. Level 5 offers the best of both world: it has excellent fault tolerance and performance.

    In addition to the various levels of RAID, there's two concepts in a RAID environment that can further simplify drive management. The first is known as drive hotswap. This allows the user to replace a crashed drive in a RAID array, without having to power the system down. The user takes the bad drive out of the drive bay, replace it with a new drive, and insert the drive bay back into the system. All the time while the server is up and running.

    The other concept is spare pooling for a RAID level 5 array. This allows the user to set up a number of spare drive(s). When a drive in the array crashes, the RAID controller will automatically take a drive from the spare pool and add it to the existing array.

    Related links:

 

Google
 

 

 

 

Copyright © 1998 The Computer Guys

 Back Home Up Next