Multicore designs Pentium D dual core processors

Main article: Multi-core (computing)

A different approach to improving a computer's performance is to add extra processors, as in symmetric multiprocessing designs, which have been popular in servers and workstations since the early 1990s. Keeping up with Moore's Law is becoming increasingly challenging as chip-making technologies approach the physical limits of the technology.

In response, the microprocessor manufacturers look for other ways to improve performance, in order to hold on to the momentum of constant upgrades in the market.

A multi-core processor is simply a single chip containing more than one microprocessor core, effectively multiplying the potential performance with the number of cores (as long as the operating system and software is designed to take advantage of more than one processor). Some components, such as bus interface and second level cache, may be shared between cores. Because the cores are physically very close they interface at much faster clock rates compared to discrete multiprocessor systems, improving overall system performance.

In 2005, the first personal computer dual-core processors were announced and as of 2009 dual-core and quad-core processors are widely used in servers, workstations and PCs while six and eight-core processors will be available for high-end applications in both the home and professional environments.

Sun Microsystems has released the Niagara and Niagara 2 chips, both of which feature an eight-core design. The Niagara 2 supports more threads and operates at 1.6 GHz.

High-end Intel Xeon processors that are on the LGA771 socket are DP (dual processor) capable, as well as the Intel Core 2 Extreme QX9775 also used in the Mac Pro by Apple and the Intel Skulltrail motherboard. With the transition to the LGA1366 socket and the Intel i7 chip quad core is now considered mainstream and the upcoming i9 chip will introduce six and possibly dual-die hex-core (12-cores), processors.

RISC

In the mid-1980s to early-1990s, a crop of new high-performance Reduced Instruction Set Computer (RISC) microprocessors appeared, influenced by discrete RISC-like CPU designs such as the IBM 801 and others. RISC microprocessors were initially used in special-purpose machines and Unix workstations, but then gained wide acceptance in other roles.

In 1986, HP released its first system with a PA-RISC CPU. The first commercial microprocessor design was released either by MIPS Computer Systems, the 32-bit R2000 (the R1000 was not released) or by Acorn computers, the 32-bit ARM2 in 1987.[citation needed] The R3000 made the design truly practical, and the R4000 introduced the world's first commercially available 64-bit RISC microprocessor. Competing projects would result in the IBM POWER and Sun SPARC architectures. Soon every major vendor was releasing a RISC design, including the AT&T CRISP, AMD 29000, Intel i860 and Intel i960, Motorola 88000, DEC Alpha.

As of 2007, two 64-bit RISC architectures are still produced in volume for non-embedded applications: SPARC and Power ISA.

Intel 4004

Intel

The Intel 4004 is generally considered the first microprocessor,^[6][7] and cost in the thousands of dollars.^[8] The first known advertisement for the 4004 is dated to November 1971; it appeared in Electronic News.^[9] The project that produced the 4004 originated in 1969, when Busicom, a Japanese calculator manufacturer, asked Intel to build a chipset for high-performance desktop calculators. Busicom original design called for a programmable chip set consisting of 7 different chips, three of them were used to make a special-purpose CPU with its program stored in ROM and its data stored in shift register read-write memory. Ted Hoff, the Intel engineer assigned to evaluate the project, believed the Busicom design could be simplified by using dynamic RAM storage for data, rather than shift register memory, and a more traditional general-purpose CPU architecture. Hoff came up with a four–chip architectural proposal: a ROM chip for storing the programs, a dynamic RAM chip for storing data, a simple I/O device and a 4-bit central processing unit (CPU), which he felt could be integrated into a single chip, although he was not a chip designer. This chip would later be called the 4004 microprocessor.

The architecture and specifications of the 4004 were the results of the interaction of Intel’s Hoff with Stanley Mazor, a software engineer reporting to Hoff, and with Busicom engineer Masatoshi Shima. In April 1970 Intel hired Federico Faggin to lead the design of the four-chip set. Faggin, who originally developed the silicon gate technology (SGT) in 1968 at Fairchild Semiconductor^[10] (and also designed the world’s first commercial integrated circuit using SGT – the Fairchild 3708), had the correct background to lead the project since it was the SGT to make possible the design of a CPU into a single chip with the proper speed, power dissipation and cost. Faggin also developed the new methodology for random logic design, based on silicon gate, that made the 4004 possible. Production units of the 4004 were first delivered to Busicom in March 1971, and shipped to other customers in late 1971.

Although the Intel 4004 is considered the first microprocessor, there were microprocessors embedded in industrial controllers. Some examples are automated gas pumps, traffic controllers, and flow meters.^{[citation needed]}

What is microproccessor?

A microprocessor incorporates most or all of the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC, or microchip).^[1] The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4- and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc, followed rather quickly. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general purpose microcomputers in the mid-1970s.

Computer processors were for a long period constructed out of small and medium-scale ICs containing the equivalent of a few to a few hundred transistors. The integration of the whole CPU onto a single chip therefore greatly reduced the cost of processing capacity. From their humble beginnings, continued increases in microprocessor capacity have rendered other forms of computers almost completely obsolete (see history of computing hardware), with one or more microprocessor as processing element in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers.

Since the early 1970s, the increase in capacity of microprocessors has been known to generally follow Moore's Law, which suggests that the complexity of an integrated circuit, with respect to minimum component cost, doubles every two years.^[4]

In the late 1990s, and in the high-performance microprocessor segment, heat generation (TDP), due to switching losses, static current leakage, and other factors, emerged as a leading developmental constraint.^[5]