|THE HISTORY OF MICROPROCESSOR
During 1960s, computer processors were constructed from small and medium scale ICs each having from ten (10) to hundred (100) transistors. For each computer built, all of these had to be placed and soldered onto printed circuit boards and often multiple boards would have to be interconnected. The large number of discrete logic gates used more electrical power and therefore, produced more heat than a more integrated design with less number of ICs. The distance at which signals had to travel between ICs on the boards limited the speed at which a computer could operate. In the NASA Apollo space missions to the moon in the 1960s and 1970s, all onboard computations for primary guidance, navigation and control were provided by a small custom processor called "The Apollo Guidance Computer". It used wire wrap circuit boards whose only logic elements were three inputs NOR gates.
The integration of a whole CPU on a single chip or on a few chips highly reduced the cost of processing power. The integrated circuit processor was produced in large numbers by highly automated processes, so unit cost was low. Single chip processors increase reliability as there are many fewer electrical connections to fail. As microprocessor designs get faster, the cost of manufacturing a chip (with smaller components built on a semiconductor chip of the same size) generally remains the same. And later in 1970s, microprocessors were emerged. 1970s, the increase in capacity of microprocessors has followed Moore’s law (which Moore stated in 1965), which stated that the number of transistors that can be fitted onto a chip doubles in one and half year but present technology doubles every two year, though even Moore also extended the period to two years.
In 1968, Robert Noyce, Gordan Moore and Andrew Grove resigned from Fairchild semiconductorsand founded their own company named Intel (Integrated Electronics). Intel grown from 3 man start-up in 1968 and introduced the first microprocessor in 1971.
The history of microprocessor starts in 1971 with the invention of the intel 4004 (General Purpose Microprocessor) microprocessor. It was a 4-bit microprocessor and has clock speed of 740KHz and have 2,300 transistors and could execute 60,000 instructions per second. The Intel 4004 microprocessor was designed for electronic calculator and have cost of $60. Around the same time, Intel developers began working on the 1201 project for Computer Terminal Corportion (CTC). 1201 was a single metal-oxide semiconductor (MOS) chip that would replace a similar processer designed using medium scale integration components. And 1201 was later renamed as Intel 8008. It was introduced in 1972 and the first 8-bit microprocessor and laid the foundation for future Intel microprocessors. The 8008 was designed in 10-micron PMOS (metal-oxide semiconductor of p-type transistor) technology. It requires 3,500 transistors and was packaged in an 8-pin dual inline package. Its clock speed was 500KHz and could execute 50,000 instructions per second. The Intel 8008 microprocessor was designed for a computer terminal. In 1974, INTEL produced Intel 8080 microprocessor which have much improved performance over 8008 and require less support chips than Intel 8008. It wa also 8-bit microprocessor and having clock speed of 2MHz. It has 6,000 transistors and was 10 times faster than 8008 and could execute 5,00,000 instructions per second. In 1974, Intel also introduced Intel 4040 microprocessor which was a 4-bit microprocessor.
In 1976,Intel 8085 was introduced. It was also 8-bit microprocessor and its clock speed was 3MHz. Its Data bus is 8-bit and address bus is of 16-bit and it has 6,500 transistors. It could execute 7,69,230 instructions per second and could acess 64KB of memory and it had 246 instructions. Over 100 million of Intel 8085 copies were sold.
In 1974, Motorola also entered in the market of microprocessors by introducing 8-bit 6800 microprocessor which are using or which required 4000 transistors and was fabricated in NMOS technology. The 6800 have some significant advantages over 8008, including improved performance and need 6800 need only a single 5 volt supply. The 6800 conatined two general purpose 8-bit registers and also contained a single Index register. It means that 6800 operated on data primarily in memory but 6800 have limited use in microcomputers. The most significant application of 6800 was initially the automotive market. Motorola first produced a custom version of 6800 for motors and and later for Ford.
The 8080 and 6800 provided excellent examples to the state of the art of microprocessors but they were in some way surpassed by the continued work of their creators. Chuck Peddle left Motorola and joined MOS technologies and MOS technologies produces 6502. Also some best creators of Intel microprocessors left Intel in 1975 to form Zilog and produced Z80 microprocessors.The 6502 and Z80 are those microprocessors which powered the first microcomputers. The 6502, MOS technology was loosely based on the 6800 technology. 6502 supported 16-bit address bus and contained one 8-bit general purpose register, two 8-bit index registers and an 8-bit stack pointer. The most significant and important feature of 6502 was its price as it was introduced. At that time, microprocessor 8080 cost $150 and 6502 was available only at $25. its low cost led it to use in microcomputers such as the Apple 2 and Commodore PET. Also original 6502 with some variations were used in the Comodore 64 Atari 2600, the Nintendo Entertainment System (NES) and the Super NES.
2.5MHz Zilog Z80 was released in 1976 and were more compatible than 8080 and have many significance over 8080. The instruction set was added in Z80 and included a block move and I/O instructions. A second register was added to better support interrupts and operating systems. The Z80 interface simplified the system design by providing dynamic random access memory (DRAM) refresh signals and an on chip clock circuit. Z80 outsells the 8080 as it becomes the microprocessor of choice in many applications. The most significant application of Z80 was Tandy TRS-80 microcomputer, which was introduced in 1977.
Some other microprocessors were introduced in 1974 such as the RCA 1802 which was designed using complementary MOS (CMOS) tecnologies. The 1802 run at 6.4 MHz and need 10 volt supply, making it one of the fastest microprocessor of that time. Its designed include 16-bit registers and uses 8-bit opcode to implement the limited instruction set. The most important application of 1802 were in several NASA space probes. And in 1976, 8-bit National Semicomductor single-chip microprocessor (SC/MP) was introduced. It was the first microprocessor to support multiple bus masters on its system bus. This feature supported multiple SC/MPs and other bus masters, such as direct memory access (DMA) controller. The 16-bit TI TMS9900, also introduced in 1976, was the first single-chip 16-bit microprocessor. Its architecture was based on the TI 990 minicomputer. The TMS9900 have only two 16-bit internal registers with one of them pointing to the memory-resident register set and also the TMS9940 was introduced.
Intel introduced 8086 in 1978 and was the first 16-bit microprocessor, having clock speed of 4.77MHz, 8MHz and 10MHz depending upon the version of microprocessor. Its data bus is 16-bit and address bus is 20-bit. It has 29,000 transistors and could execute 2.5 million instructions per second. It could access 1mb of memory and had 22,000 instruction and also had multiply and divide instructions. Intel in 1979 introduced 8088, which was also of 16-bit and was a cheaper version of 8086. It was 16-bit processor and an 8-bit external busand could execute 2.5 million instructions per second. 8088 became the most popular microprocessor in the computer industry when IBM used it for its first PC. Intel also introduced 80186 and 80188,which were also of 16-bits and having clock speed of 6 MHz. 80188 was a cheaper version of 80186 with an 8-bit of external data bus. They had additional components like interrupt controller, clock generator, local bus controller and counters. Other 16-bit Intel microprocessors are 80286 which was introduced in 1982 and uses 1,34,000 transistors and could execute 4 million instructions persecond.
Intel introduced first 32-bit microprocessor 80386, which had data bus 32-bit and address bus also of 32-bit and could address 4GB of data. It had 2,75,000 transistors and having clock speed varied from 16 MHz to 33MHz depending upon the various versions. It had different versions like 80386 DX, 80386 SX, 80386 SL. It was the best selling microprocessor in the history. In 1989, Intel introduced a 32-bit microprocessor 80486 having 1.2 million transistors. It had clock speed varies from 16 MHz to 100 MHz depending upon the various versions. It had five different versions as 80486 DX, 80486 SX, 80486 DX2, 80486 SL, 80486 DX4. It had cache memory of 8KB. In 1993, Intel introduced Intel Pentium originally named as 80586 having cache memory of 8-KB for instructions and 8KB for data. In 1995, Intel Pentium pro was introduced, which was also of 32-bit and had L2 cache of 256 KB. In 1997, Intel Pentium 2 was introduced and in 1998, Intel Pentium 2 Xeon was introduced. Intel Pentium 3 was introduced in 1999, also of 32-bit and had 9.5 million of transistors. Intel Pentium 4 was introduced in 2000 and had 42 million transistors. It is also 32-bit microprocessor. Intel dual core was introduced in 2006 (32-bit or 64-bit).
In 2006, Intel core 2 (64-bit) was introduced and also launched its different versions such as Intel core 2 duo, Intel core 2 Quad, Intel core 2 extreme. It has 64 KB of L1 cache per core and 4MB of L2 cache. Intel Core i7 (64-bit) was introduced in 2008 and has four physical cores. Its has 781 million transistors. It has 64Kb of L1 cache per core, 256 KB of L2 cache and 8MB of L3 cache. Intel introduced Intel Core i5 (64-bit) in 2009. Its clock speed is from 2.40 GHz to 3.60 GHz and also having four physical cores. It has 64KB of L1 cache per core, 256 KB of L2 cache and 8MB of L3 cahce. And Intel introduced core i3 (64-bit) in 2010 and has 2 physical cores. Its clock speed is from 2.93 GHz to 3.33 GHz and has 781 million transistors. It has 64KB of L1 cache per core, 512 KB of L2 cache and 4MB of L3 cache.