CompTIA A+ Exam Prep: Microprocessors

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CompTIA A+ Exam Prep (Exams A+ Essentials, 220-602, 220-603, 220-604)

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This chapter is from the book

This chapter is from the book 

CompTIA A+ Exam Prep (Exams A+ Essentials, 220-602, 220-603, 220-604)

Learn More Buy

AMD Processors

Advanced Micro Devices (AMD) offers several clone microprocessors: the 5x86 (X5), 5x86 (K5), K6, K6PLUS-3D, and K7 microprocessors. The X5 offers operational and pin compatibility with the 80486DX4. Its performance is equal to that of the Pentium and MMX processors. The K5 processor is compatible with the Pentium, and the K6 is compatible with the MMX. Both the K5 and K6 models are Socket 7 compatible, enabling them to be used in conventional Pentium and Pentium MMX system board designs (with some small modifications). The K6 employs an extended 64KB L1 cache that doubles the internal cache size of the Pentium II.

The K6PLUS-3D is operationally and performance compatible with the Pentium Pro, and the K7 is operationally and performance compatible with the Pentium II. However, neither of these units has a pin-out compatibility with another processor.

AMD continued to produce clone versions of Pentium processors. In some cases, the functions and performance of the AMD devices went beyond those of the Intel design they are cloning. Two notable AMD Pentium clone processors are the Athlon and the Duron.

The Athlon is a Pentium III clone processor. It is available in a Slot 1 cartridge clone, called the Slot A specification. Figure 3.11 shows the front and back sides of the cartridge version of the Athlon processor along with a Slot A connector.

Figure 3.11 The Slot A Athlon processor.

The Athlon is also available in a proprietary SPGA Socket A design that mimics the Intel Socket 370 specification. The Socket A specification employs a 462-pin ZIF socket and is supported only by two available chipsets.

The first Athlon version was the K7 version that ran between 500MHz and 700MHz, provided a 128KB L1 cache and a 512KB L2 cache, and employed a 100MHz system bus. Subsequent Athlon versions have included the K75, Thunderbird, Thoroughbred, and Barton versions. These versions are constructed using the improved 0.18-micron manufacturing technology.

The K75 processors operated at speeds between 750MHz and 1GHz, provided a 128KB L1 cache and a 512KB L2 cache, and employed a 100MHz system bus. The Thunderbird version ran between 750MHz and 1.2GHz, provided a 128KB L1 cache and a 256KB L2 cache, and employed a 133MHz system bus. The Thoroughbred version featured 256KB of L2 cache along with the standard 64+64KB L1 cache and operated at speeds up to 2.8GHz.

An even later evolution of the Athlon processor was given the title of Athlon XP. These versions were based on the Thoroughbred and the newer Barton core versions. The Barton versions feature a 512KB L2 cache, a slower clock speed, and a maximum processor speed of 3.0GHz.

Athlon 64 Processors

AMD made several technology changes to the Athlon processor when it unveiled its Athlon 64 line of processors. These processors are built on a new core that includes the AMD64 64-bit architecture. This architecture is an extension of the x86 Instruction Set that was originally created by Intel for its 80x86 line of processors. In addition, the Athlon 64 architecture implemented additional internal registers to support independent floating-point math operations.

A new No-Execute (NE) bit technology was also introduced with the Athlon 64. NE technology marks different areas of memory as being for use with data or as being reserved for instructions. Any attempt to execute code from a memory page that has been tagged as a no-execute page will result in a memory access violation error. This feature makes it more difficult for certain types of malware to take control of the system and execute its payload.

The Athlon 64 processor introduced another considerable change to Pentium class PC architecture by moving the memory controller from the supporting system board chipset into the microprocessor package. This effectively removes the front-side bus from the system architecture and improves memory access operations by avoiding external bus access overhead.

Instead of continuing the traditional FSB structure, AMD adopted a special bidirectional, serial/parallel I/O bus and controller technology from the HyperTransport Technology Consortium for its Athlon 64 processors. The HyperTransport (HT) technology handles the I/O functions previously performed across the FSB at speeds much higher than existing FSB clocking. AMD also employs this bus to interconnect multiple processor cores to provide efficient cooperation between the cores.

The Athlon 64 FX is a special designation given to some Athlon 64 versions. These processors are typically clocked faster than the traditional Athlon versions to make them more interesting to gamers and other enthusiasts.

There are two common socket sizes used with Athlon 64 processors: a 754-pin socket for a value/budget version of the Athlon 64 that provides only a 64-bit, single-channel memory interface, and a 939-pin version that is the standard for all other Athlon 64 versions.

Duron Processors

The Duron processor is a Celeron clone processor that conforms to the AMD Socket A specification. The Duron features processor speeds between 600MHz and 800MHz. It includes a 128KB L1 cache and a 64KB L2 cache and employs a 100MHz system bus. Like the newer Celerons, the Duron is constructed using 0.18-micron IC manufacturing technology.

Athlon Dual-Core Processors

AMD took the lead in the processor development races by pushing dual-core processors to the forefront. Unlike the Intel dual-core processors discussed earlier in the chapter, AMD designed its dual-core devices to fit in the same 939-pin socket interface it was already using for its single-core Athlon 64 processor. In addition, the existing Athlon 64 chipset had been designed with this possibility in mind. These features make upgrading to dual-core processors relatively easy and attractive. All that is required is to physically exchange the microprocessor packages and perform a logical upgrade by flashing the system's ROM BIOS with programming to support the new processor.

Figure 3.12 provides a block diagram of the AMD Athlon 64 X2 Dual-Core processor design. Unlike the Intel processors, the dual processor cores in the 64 X2 can communicate with each other through the System Request Interface. This interface enables communications to take place at the core clock speed of the processors.

Figure 3.12 The AMD dual-core processor's design.

The AMD multicore technology also changed the front-side bus arrangement found in existing Pentium/PCI systems. This portion of the system has been redesigned in a Direct Connect Architecture that directly connects the processors, the memory controller, and the HyperTransport (I/O) controller to the CPU through the Crossbar Switch portion of the System Request Interface inside the processor. This gives the processors direct on-chip access to the 128-bit ECC memory controller (in contrast to having to access an external bus to get to the North Bridge).

The complete line of AMD64 devices (single and dual core) offers AMD's advanced HyperTransport bus interface technology for high-speed I/O communication. This interface consists of an integrated HyperTransport controller and a 16-bit, 1GHz bus that interconnects the cores of the multicore AMD processor through its Direct Connect Architecture and provides 8GBps transfer rates. The HyperTransport interface also connects the processor package to the system board's chipset. This connection scheme is shown in Figure 3.13.

Figure 3.13 HyperTransport links.

The AMD 64 X2 has been built on two different microprocessor core types. Both versions include dual AMD64 microprocessor cores. These cores are rated to operate at core voltages between 1.35V and 1.4V. Likewise, they both contain dual 64+64 (Data/Instructions) L1 cache memory units. They also run identical microprocessor instruction sets and extensions. Finally, they both work with Socket-939 structure and provide 1GHz HyperTransport high-speed I/O interfaces.

The 4400+ processor runs on a 2.2GHz clock and the 4800+ uses a 2.4GHz clock. Both versions provide a 1MB full speed L2 cache for each core. They also dissipate 89 or 110 watts of power. On the other hand, the 3800+is designed for a 2.0GHz clock, the 4200+ uses a 2.2GHz clock, and the 4600+ version employs a 2.4GHz clock. In these versions, the L2 cache is limited to 512KB for each core and the power dissipation is limited to 110W max.

The Athlon 64 X2 is supported by a number of chipsets from many manufacturers. These include:

• NVIDIA—Nforce4 Series chipsets
• ATI—Radeon Xpress 200 Series chipsets
• VIA—K8 Series chipsets
• SiS—75x Series chipsets or greater

In at least one case (NVIDIA nFORCE Professional), the chipset designed to support the AMD dual-core processor is a single chip, as shown in Figure 3.14. The AMD processors provide direct connection to the system's DDR memory through its Direct Connect Architecture, and the nFORCE chipset handles the PCIe graphics, Ethernet networking, and SATA disk-drive interfaces.

Figure 3.14 A single-chip AMD chipset.

Like the dual-core Intel processors, the Athlon 64 X2 supports a 64-bit extension to the x86 Instruction set, enhanced virus protection with supported operating systems, and speed throttling features. In the AMD environment, these features are known as AMD64, NX (no execute bit), and CoolnQuiet. The functions associated with these features are roughly the same as those of the Intel EM64T, XD bit, and SpeedStep features described earlier in this chapter.

Opteron Processors

AMD has also produced a line of dual-core, high-end Opteron processors for network server and workstation units. These units are built on AMD's K8 core and are intended to compete with Intel's Xeon line of processors. The original 1XX Opteron versions were built for a 939-pin socket. However, newer 2XX and 8XX 940-pin versions have been introduced for the newer Socket M2 (AM2) specification. As mentioned in Chapter 2, "PC System Boards," several Athlon64, Athlon 64 FX, Athlon64 X2, and Sempron processor versions have been developed to use the Socket M2 specification. Table 3.2 lists the prominent features of the dual-core Opteron processors from AMD.

Table 3.2. AMD Dual-Core Opteron Processors

Table 3.3 summarizes the characteristics of common Intel and AMD microprocessors. Both companies add new or upgraded processors to their product lines on a regular basis. Therefore, this list is not intended to be a complete list of all existing processors, just the main ones in existence up to the time when the text was created.

Table 3.3. Microprocessor Characteristics

Table 3.3. Microprocessor Characteristics (cont.)