Processor Specifications

Processor Specifications
Many confusing specifications often are quoted in discussions of processors. The following sections discuss some of these specifications, including the data bus, address bus, and speed. The next section includes a table that lists the specifications of virtually all PC processors. Processors can be identified by two main parameters: how wide they are and how fast they are. The speed of a processor is a fairly simple concept. Speed is counted in megahertz (MHz) and gigahertz (GHz), which means millions and billions, respectively, of cycles per second—and faster is better! The width of a processor is a little more complicated to discuss because three main specifications in a processor are expressed in width. They are ¦ Data I/O bus ¦ Internal registers ¦ Address bus
First, I’ll present some tables describing the differences in specifications between all the PC processors; then the following sections will explain the width and other specifications in more detail. will become clearer that the Pentium Pro processor includes 256KB, 512KB, or 1MB of full-core speed L2 cache in a separate die within the chip. The earlier Pentium II/III processors include 512KB of half-core speed L2 cache on the processor card. The Celeron, Pentium II PE, and Pentium IIIE and IIIB processors include full-core speed L2 cache integrated directly within the processor die. The Celeron III uses the same die as the Pentium IIIE, but half of the on-die cache is disabled,leaving 128KB functional. Older Celerons were based on the Pentium II and III, whereas the Celeron 4 is actually aPentium 4. The later Pentium 4A includes 512KB of on-die full-core speed L2 cache.The transistor count figures do not include the external (of f-die) 256KB, 512KB, 1MB, or 2MB L2 cache built into the Pentium Pro, Pentium II/III, Xeon, and AMD Athlon CPU packages or the 2MB or 4MB of L3 cache in the Itanium. The external L2 cache in those processors contains an additional 15.5 (256KB), 31 (512KB), 62 million (1MB), or 124 million (2MB) transistors in separate chips, whereas the external 2MB or 4MB of L3 cache in the Itanium includes up to 300 million transistors!

The original AMD Athlon included 512KB of L2 cache via separate chips, running at either onehalf, two-fifths, or one-third the core speed, and later Athlon TB (Thunderbird) or XP models include 256KB of on-die L2 running at full-core speed.