|
|
Free Open Book
Upgrading and Repairing PCs |
|
Other Sixth-Generation ProcessorsBesides Intel, many other manufacturers have produced P6-type processors, but often with a difference. Most of them are designed to interface with P5 class motherboards and for the lower-end markets. AMD has recently offered up the Athlon and Duron processors, which are true sixth-generation designs using their own proprietary connections to the system. This section examines the various sixth-generation processors from manufacturers other than Intel. NexGen Nx586NexGen was founded by Thampy Thomas, who hired some of the people formerly involved with the 486 and Pentium processors at Intel. At NexGen, developers created the Nx586, a processor that was functionally the same as the Pentium but not pin compatible. As such, it was always supplied with a motherboard; in fact, it was usually soldered in. NexGen did not manufacture the chips or the motherboards they came in; for that it hired IBM Microelectronics. Later NexGen was bought by AMD, right before it was ready to introduce the Nx686—a greatly improved design by Greg Favor and a true competitor for the Pentium. AMD took the Nx686 design and combined it with a Pentium electrical interface to create a drop-in Pentium-compatible chip called the K6, which actually outperformed the original from Intel. The Nx586 had all the standard fifth-generation processor features, such as superscalar execution with two internal pipelines and a high-performance integral L1 cache with separate code and data caches. One advantage is that the Nx586 includes separate 16KB instruction and 16KB data caches compared to 8KB each for the Pentium. These caches keep key instruction and data close to the processing engines to increase overall system performance. The Nx586 also includes branch prediction capabilities, which are one of the hallmarks of a sixth-generation processor. Branch prediction means the processor has internal functions to predict program flow to optimize the instruction execution. The Nx586 processor also featured a RISC core. A translation unit dynamically translates x86 instructions into RISC86 instructions. These RISC86 instructions were designed specifically with direct support for the x86 architecture while obeying RISC performance principles. They are thus simpler and easier to execute than the complex x86 instructions. This type of capability is another feature normally found only in P6 class processors. The Nx586 was discontinued after the merger with AMD, which then took the design for the successor Nx686 and released it as the AMD-K6. AMD-K6 SeriesThe AMD-K6 processor is a high-performance sixth-generation processor that is physically installable in a P5 (Pentium) motherboard. It essentially was designed for AMD by NexGen and was first known as the Nx686. The NexGen version never appeared because it was purchased by AMD before the chip was due to be released. The AMD-K6 delivers performance levels somewhere between the Pentium and Pentium II processor as a result of its unique hybrid design. Because it is designed to install in Socket 7, which is a fifth-generation processor socket and motherboard design, it can't quite perform as a true sixth-generation chip because the Socket 7 architecture severely limits cache and memory performance. However, with this processor, AMD gave Intel a lot of competition in the low- to mid-range market, where the Pentium was still popular. The K6 processor contains an industry-standard, high-performance implementation of the new multimedia instruction set, enabling a high level of multimedia performance. The K6-2 introduced an upgrade to MMX that AMD calls 3DNow!, which adds even more graphics and sound instructions. AMD designed the K6 processor to fit the low-cost, high-volume Socket 7 infrastructure. Initially, it used AMD's 0.35-micron, five-metal layer process technology; more recent variations used the 0.25-micron processor to increase production quantities because of reduced die size, as well as to decrease power consumption. AMD-K6 processor technical features include:
The K6-3 adds the following:
The addition of the full-speed L2 cache in the K6-3 was significant. It enables the K6 series to fully compete with the Intel Pentium II processors and the Celeron processors based on the Pentium II. The 3DNow! capability added in the K6-2/3 was also exploited by newer graphics programs, making these processors ideal for lower-cost gaming systems. The AMD-K6 processor architecture is fully x86 binary code compatible, which means it runs all Intel software, including MMX instructions. To make up for the lower L2 cache performance of the Socket 7 design, AMD beefed up the internal L1 cache to 64KB total, twice the size of the Pentium II or III. This, plus the dynamic execution capability, enabled the K6 to outperform the Pentium and come close to the Pentium II and III in performance for a given clock rate. The K6-3 was even better with the addition of full-core speed L2 cache; however, this processor ran very hot and was discontinued after a relatively brief period. Both the AMD-K5 and AMD-K6 processors are Socket 7 bus compatible. However, certain modifications might be necessary for proper voltage setting and BIOS revisions. To ensure reliable operation of the AMD-K6 processor, the motherboard must meet specific voltage requirements. The AMD processors have specific voltage requirements. Most older split-voltage motherboards default to 2.8V Core/3.3V I/O, which is below specification for the AMD-K6 and could cause erratic operation. To work properly, the motherboard must have Socket 7 with a dual-plane voltage regulator supplying 2.9V or 3.2V (233MHz) to the CPU core voltage (Vcc2) and 3.3V for the I/O (Vcc3). The voltage regulator must be capable of supplying up to 7.5A (9.5A for the 233MHz) to the processor. When used with a 200MHz or slower processor, the voltage regulator must maintain the core voltage within 145 mV of nominal (2.9V+/–145 mV). When used with a 233MHz processor, the voltage regulator must maintain the core voltage within 100 mV of nominal (3.2V+/–100 mV). If the motherboard has a poorly designed voltage regulator that cannot maintain this performance, unreliable operation can result. If the CPU voltage exceeds the absolute maximum voltage range, the processor can be permanently damaged. Also note that the K6 can run hot. Make sure your heatsink is securely fitted to the processor and that the thermally conductive grease or pad is properly applied. The motherboard must have an AMD-K6 processor-ready BIOS with support for the K6 built in. Award has that support in its March 1, 1997 or later BIOS; AMI had K6 support in any of its BIOS with CPU Module 3.31 or later; and Phoenix supports the K6 in version 4.0, release 6.0, or release 5.1 with build dates of 4/7/97 or later. Because these specifications can be fairly complicated, AMD keeps a list of motherboards that have been verified to work with the AMD-K6 processor on its Web site. All the motherboards on that list have been tested to work properly with the AMD-K6. So, unless these requirements can be verified elsewhere, it is recommended that you use only a motherboard from that list with the AMD-K6 processor. The multiplier, bus speed, and voltage settings for the K6 are shown in Table 3.31. You can identify which AMD-K6 you have by looking at the markings on this chip, as shown in Figure 3.59. Figure 3.59. AMD-K6 processor markings.
Older motherboards achieve the 3.5x setting by setting jumpers for 1.5x. The 1.5x setting for older motherboards equates to a 3.5x setting for the AMD-K6 and newer Intel parts. Getting the 4x and higher setting requires a motherboard that controls three BF pins, including BF2. Older motherboards can control only two BF pins. The settings for the multipliers are shown in Table 3.32.
These settings usually are controlled by jumpers on the motherboard. Consult your motherboard documentation to see where they are and how to set them for the proper multiplier and bus speed settings. Unlike Cyrix and some of the other Intel competitors, AMD is a manufacturer and a designer. Therefore, it designs and builds its chips in its own fabs. Similar to Intel, AMD has migrated to 0.25-micron process technology and beyond (the AMD Athlon XP is built on a 0.13-micron process). The original K6 has 8.8 million transistors and is built on a 0.35-micron, five-layer process. The die is 12.7mm on each side, or about 162 square mm. The K6-3 uses a 0.25-micron process and incorporates 21.3 million transistors on a die only 10.9mm on each side, or about 118 square mm. Because of its performance and compatibility with the Socket 7 interface, the K6 series is often looked at as an excellent processor upgrade for motherboards using older Pentium or Pentium MMX processors. Although they do work in Socket 7, the AMD-K6 processors have different voltage and bus speed requirements from the Intel processors. Before attempting any upgrades, you should check the board documentation or contact the manufacturer to see whether your board meets the necessary requirements. In some cases, a BIOS upgrade also is necessary. AMD Athlon, Duron, and Athlon XPThe Athlon is AMD's successor to the K6 series (refer to Figure 3.60). The Athlon is a whole new chip from the ground up and does not interface via the Socket 7 or Super7 sockets like its previous chips. In the initial Athlon versions, AMD used a cartridge design, called Slot A, almost exactly like that of the Intel Pentium II and III. This was due to the fact that the original Athlons used 512KB of external L2 cache, which was mounted on the processor cartridge board. The external cache ran at one-half core, two-fifths core, or one-third core depending on which speed processor you had. In June 2000, AMD introduced a revised version of the Athlon (codenamed Thunderbird) that incorporates 256KB of L2 cache directly on the processor die. This on-die cache runs at full-core speed and eliminates a bottleneck in the original Athlon systems. Along with the change to on-die L2 cache, the Athlon was also introduced in a PGA or chip Socket A version, which replaced the Slot A cartridge version. The most recent Athlon version, called the Athlon XP, has several enhancements such as 3DNow! Figure 3.60. AMD Athlon processor for Slot A (cartridge form factor).
Professional instructions, which also include the Intel SSE instructions. The latest Athlon XP models have also returned to the use of 512KB L2 cache, but this time at full processor speed. Although the Slot A cartridge looks a lot like the Intel Slot 1, and the Socket A looks like Intel's Socket 370, the pinouts are completely different and the AMD chips do not work in the same motherboards as the Intel chips. This was by design because AMD was looking for ways to improve its chip architecture and distance itself from Intel. Special blocked pins in either socket or slot design prevent accidentally installing the chip in the wrong orientation or wrong slot. Figure 3.60 shows the Athlon in the Slot A cartridge. Socket A versions of the Athlon closely resemble the Duron. The Athlon is available in speeds from 550MHz up to 1.4GHz and uses a 200MHz or 266MHz processor (front-side) bus called the EV6 to connect to the motherboard North Bridge chip as well as other processors. Licensed from Digital Equipment, the EV6 bus is the same as that used for the Alpha 21264 processor, now owned by Compaq. The EV6 bus uses a clock speed of 100MHz or 133MHz but double-clocks the data, transferring data twice per cycle, for a cycling speed of 200MHz or 266MHz. Because the bus is 8 bytes (64 bits) wide, this results in a throughput of 8 bytes times 200MHz/266MHz, which amounts to 1.6GBps or 2.1GBps. This bus is ideal for supporting PC1600 or PC2100 DDR memory, which also runs at those speeds. The AMD bus design eliminates a potential bottleneck between the chipset and processor and enables more efficient transfers compared to other processors. The use of the EV6 bus is one of the primary reasons the Athlon and Duron chips perform so well. The Athlon has a very large 128KB of L1 cache on the processor die and one-half, two-fifths, or one-third core speed 512KB L2 cache in the cartridge in the older versions; 256KB of full-core speed cache in Socket A Athlon and most Athlon XP models; and 512KB of full-core speed cache in the latest Athlon XP models. All PGA socket A versions have the full-speed cache. The Athlon also has support for MMX and the Enhanced 3DNow! instructions, which are 45 new instructions designed to support graphics and sound processing. 3DNow! is very similar to Intel's SSE in design and intent, but the specific instructions are different and require software support. The Athlon XP adds the Intel SSE instructions, which it calls 3DNow! Professional. Fortunately, most companies producing graphics software have decided to support the 3DNow! instructions along with the Intel SSE instructions, with only a few exceptions. The initial production of the Athlon used 0.25-micron technology, with newer and faster versions being made on 0.18-micron and 0.13-micron processes. The latest versions are even built using copper metal technology, a first in the PC processor business. Eventually all other processors will follow because copper connects allow for lower power consumption and faster operation. Table 3.33 shows detailed information on the Slot A version of the Athlon processor. Table 3.34 shows information on the PGA or Socket A version of the AMD Athlon processor. All Socket A processors are Model 4. Table 3.33. AMD Athlon Slot A Cartridge Processor Information
Table 3.34. AMD Athlon PGA (Socket A) Processor Information
In most benchmarks the AMD Athlon compares as equal, if not superior, to the Intel Pentium III. AMD beat Intel to the 1GHz mark by introducing its 1GHz Athlon two days before Intel introduced the 1GHz Pentium III. AMD DuronThe AMD Duron processor (originally code named Spitfire) was announced in June 2000 and is a derivative of the AMD Athlon processor in the same fashion as the Celeron is a derivative of the Pentium II and III. Basically, the Duron is an Athlon with less L2 cache; all other capabilities are essentially the same. It is designed to be a lower-cost version with less cache but only slightly less performance. In keeping with the low-cost theme, Duron contains 64KB on-die L2 cache and is designed for Socket A, a socket version of the Athlon Slot A (see Figure 3.61). Except for the Duron markings, the Duron is almost identical externally to the Socket A versions of the original Athlon. Figure 3.61. AMD Duron processor.
Essentially, the Duron was designed to compete against the Intel Celeron in the low-cost PC market, just as the Athlon was designed to compete in the higher-end Pentium III market. The Duron has since been discontinued, but most systems that use the Duron processor can use AMD Athlon or, in some cases Athlon XP, processors as an upgrade. Because the Duron processor is derived from the Athlon core, it includes the Athlon 200MHz front-side system bus (interface to the chipset) as well as enhanced 3DNow! instructions in Model 3. Model 7 processors include 3DNow! Professional instructions (which include a full implementation of SSE instructions). Table 3.35 shows information on the PGA or Socket A version of the AMD Duron processor. Durons that require 1.6V are Model 3 processors, whereas those that require 1.75V are Model 7 processors. The Model 7 version was originally code named Morgan.
AMD Athlon XPAs mentioned earlier, the newest version of the Athlon is called the Athlon XP. This is basically an improved version of the previous Athlon, with improvements in the instruction set so it can execute Intel SSE instructions and a new marketing scheme that directly competes with the Pentium 4. The latest Athlon XP models have also adopted a larger (512KB) full-speed on-die cache. AMD uses the term "QuantiSpeed" (a marketing term, not a technical term) to refer to the architecture of the Athlon XP. AMD defines this as including the following:
These design improvements wring more work out of each clock cycle, enabling a "slower" Athlon XP to beat a "faster" Pentium 4 processor in doing actual work (and play). The first models of the Athlon XP used the Palomino core, which is also shared by the Athlon 4 mobile (laptop) processor. Later models have used the Thoroughbred core, which was later revised to improve thermal characteristics. The different Thoroughbred cores are sometimes referred to as Thoroughbred-A and Thoroughbred-B. The latest Athlon XP processors use a new core with 512KB on-die full-speed L2 cache known as Barton. Additional features include
Also new to the Athlon XP is the use of a thinner, lighter organic chip packaging compound similar to that used by recent Intel processors. Figure 3.62 shows the latest Athlon XP processors that use the Barton core. Figure 3.62. AMD Athlon XP 0.13-micron processor with 512KB of L2 cache for Socket A (PGA form factor). Photo courtesy of Advanced Micro Devices, Inc.
This packaging allows for a more efficient layout of electrical components. The latest versions of the Athlon XP are made using a new 0.13-micron die process that results in a chip with a smaller die that uses less power, generates less heat, and is capable of running faster as compared to the previous models. The newest 0.13-micron versions of the Athlon XP run at actual clock speeds exceeding 2GHz. Table 3.36 provides detailed information about the Athlon XP.
Athlon MPThe Athlon MP is AMD's first processor designed for multiprocessor support. Thus, it can be used in servers and workstations that demand multiprocessor support. The Athlon MP comes in the following three versions, which are similar to various Athlon and Athlon XP models:
All Athlon MP processors use the same Socket A interface used by later models of the Athlon and all Duron and Athlon XP processors. For more details about the Athlon MP, see the AMD Web site. Cyrix/IBM 6x86 (M1) and 6x86MX (MII)The Cyrix 6x86 processor family consists of the now-discontinued 6x86 and the newer 6x86MX processors. They are similar to the AMD-K5 and K6 in that they offer sixth-generation internal designs in a fifth-generation P5 Pentium-compatible Socket 7 exterior. The Cyrix 6x86 and 6x86MX (renamed MII) processors incorporate two optimized superpipelined integer units and an on-chip floating-point unit. These processors include the dynamic execution capability that is the hallmark of a sixth-generation CPU design. This includes branch prediction and speculative execution. The 6x86MX/MII processor is compatible with MMX technology to run MMX games and multimedia software. With its enhanced memory-management unit, a 64KB internal cache, and other advanced architectural features, the 6x86MX processor achieves higher performance and offers better value than competitive processors. Features and benefits of the 6x86 processors include
The 6x86 incorporates two caches: a 16KB dual-ported unified cache and a 256-byte instruction line cache. The unified cache is supplemented with a small, quarter-K-size, high-speed, fully associative instruction line cache. The improved 6x86MX design quadruples the internal cache size to 64KB, which significantly improves performance. The 6x86MX also includes the 57 MMX instructions that speed up the processing of certain computing-intensive loops found in multimedia and communication applications. All 6x86 processors feature support for SMM. This provides an interrupt that can be used for system power management or software transparent emulation of I/O peripherals. Additionally, the 6x86 supports a hardware interface that enables the CPU to be placed into a low-power suspend mode. The 6x86 is compatible with x86 software and all popular x86 operating systems, including Windows 95/98/Me, Windows NT/2000, OS/2, DOS, Solaris, and Unix. Additionally, the 6x86 processor has been certified Windows 95 compatible by Microsoft. As with the AMD-K6, there are some unique motherboard and BIOS requirements for the 6x86 processors. The 6x86 processor has been discontinued since Cyrix was absorbed into VIA, but the 6x86MX (MII) design is still sold and supported by VIA. Check motherboard compatibility with the 6x86MX or MII processors before integrating one into an existing Socket 7/Super 7 system. A BIOS update might be necessary in some cases. When installing or configuring a system with the 6x86 processors, you have to set the correct motherboard bus speed and multiplier settings. The Cyrix processors are numbered based on a P-Rating scale, which is not the same as the true megahertz clock speed of the processor. See the section "Cyrix Processor Speeds," earlier in this chapter, for the correct and true speed settings for the Cyrix 6x86 processors. Note that because of the use of the P-Rating system, the actual speed of the chip is not the same number at which it is advertised. For example, the 6x86MX-PR300 is not a 300MHz chip; it actually runs at only 263MHz or 266MHz, depending on exactly how the motherboard bus speed and CPU clock multipliers are set. Cyrix says it runs as fast as a 300MHz Pentium, hence the P-Rating. Personally, I wish it would label the chip at the correct speed and then say that it runs faster than a Pentium at the same speed. To install the 6x86 processors in a motherboard, you also must set the correct voltage. Normally, the markings on top of the chip indicate which voltage setting is appropriate. Various versions of the 6x86 run at 3.52V (use VRE setting), 3.3V (VR setting), or 2.8V (MMX) settings. The MMX versions use the standard split-plane 2.8V core 3.3V I/O settings. The Cyrix MII is now sold by VIA Technologies. VIA C3The VIA C3 was originally known as the VIA Cyrix III and was designed to fit into the same Socket 370 used by the Pentium III and Celeron III. The initial versions of the C3, code named Joshua and Samuel, had 128KB L1 cache but didn't contain any L2 cache. As a consequence, they had much lower performance than similar 500MHz-class processors. The original Cyrix III/C3, code named Joshua, was developed by former Cyrix engineers after VIA bought Cyrix in late 1998, but the Samuel and subsequent versions are based on the Centaur Winchip (VIA purchased Centaur in 1999). The Samuel was built with a .18-micron process, whereas the Samuel 2 is a development of the Samuel with 64KB of L2 cache on board and is built on a .15-micron process. The Ezra core was the first .13-micron process C3 processor, but it, like previous C3 processors, was not compatible with Tualatin (late Pentium III-compatible) motherboards. The Ezra-T core was the first C3 to reach 1GHz and the first to support Tualatin motherboards. The latest C3 uses the Nehemiah core and features clock speeds over 1GHz and built-in encryption. C3 models feature 100MHz FSB (750MHz and 900MHz models) or 133MHz FSP (733MHz, 800MHz, 866MHz, 933MHz, and higher). The C3 is fully software compatible with other x86 processors, including Pentium III and Celeron, but its microarchitecture is designed to enhance the performance of most frequently used instructions while reducing the performance of seldom-used instructions. This design feature significantly reduces the die size needed for C3 processors, but it also reduces performance in multimedia and graphics operations. By reducing the die size, the C3 in its Nehemiah version offers typical power consumption of only 11.25 watts, making it the coolest running processor available for Socket 370 applications. Because of its low power consumption, cool operation, and relatively low performance compared to the Intel Celeron, the C3 processor should be considered primarily for computing appliances, set-top boxes, and portable computers in which small size and low power/cooling requirements (rather than performance) are paramount. The C3 is also available in an enhanced ball grid array (EBGA) package called the E-series. E-series C3 processors are used for permanent installation on motherboards such as the Mini-ITX ultra-compact form factor designs also produced by VIA. For more details about various versions of the C3, refer to Table 3.2 or the VIA Technologies Web site.
|
Main Menu |
| 500 Juegos Gratis | 500 Giochi Gratis | 500 Jeux Gratuits | 500 Jogos Gratis | 500 Kostenlose Spiele |
