History of microprocessor

Contributor: Suryansh Gupta
The first Microprocessor (4004) was designed by Intel in 1968. A Japanese Calculator manufacturer, BUSICOM approached Intel with a design for a small calculator which needs 12 custom chips.  Ted Hoff, an Intel Engineer thought that a general purpose logic device could replace the multiple components. This idea led to the development of a microprocessor. So, Microprocessors started with a modest beginning of drivers for calculators.  Intel introduced the 4004 microprocessor to the worldwide market on November 15, 1971.  It was a 4-bit PMOS chip with 2300 transistors.  At the same time Texas Instruments developed a 4-bit microprocessor TMS 1000 and became the owner of microprocessor patent.
Later in 1972 Intel introduced world’s first 8 bit general purpose microprocessor 8008.  This processor was used in the popular computer ‘Mark-8’ in those days.  In 1974, Intel introduced the improved version of 8008, the 8080 microprocessor. This 8080 is the much more highly integrated chip than its predecessors which is built around N-channel MOS technology. It could execute up to 290,000 operations per second and could address up to 64K.bytes of memory. The other notable 8 bit microprocessors include Motorola 6800, Rockwell PPS-8 and Signetics 2650 with powerful architecture and instruction set.
In 1976 Intel released the 8 bit microprocessor with the combined of clock generator 8224 which consisted 65000 MOS transistors and operate at 3-5 MHz with +5 volt supply. At the same time Motorola also introduce MC 6809, Zilog Z-80 and RCA COSMAC microprocessor.
In 1978, Intel introduced the 16 bit microprocessor 8086 and 8088 in 1979. IBM select 8088 for designing the series of personal computer. 8086 consist 20 bit address bus and 16 bit data bus. It designed 29,000 MOS transistor and work at clock speed of 5-10 MHz Intel used first time pipelining concept in this microprocessor. 8086 and 8088 architecture and functioning are same only difference is that 8088, 8 bit microprocessor rather than the 16 bit microprocessor and pre-fetch queue is 4 instruction instead of 6 instruction.
In 1982 Intel released another 16-bit processor 80186. This controller has higher reliability faster operation with lower cost. It also suitable for high volume applications such as computer workstations, word-processor and personal computers. It is made from 134,000 MOS transistors and could work at clock rates of 4 and 6 MHz and 6 pre-fetch queue instructions. This microprocessor called first generation Microprocessors.
Intel released another 16 bit more advance microprocessor then 80186, 80286 in 1981 which have 1, 34,000 transistors. 80286 also called second generation microprocessor. It could run at clock speeds of 6 to 12.5 MHz. It has a 16-bit data bus and 24-bit address bus, so that it can address up to 16MB of address space and 1GB of virtual memory. 80286 had a pre-fetch queue of 6 instructions .Intel introduced the concept of protected mode and virtual mode to ensure proper operation in this generation processor. It also had on-chip memory management unit (MMU) .This was popularly called as Intel 286 in those days.
Intel released its first 32 bit processor 80386 with 275,000 transistors in 1985. It has 32-bit data bus as well as address bus so that it can address up the total of 4GigaByte memory and also a virtual memory space of 64TeraByte. It could process five millions of instruction per/sec and can work with all the popular operating systems including Windows operating system. It has a pre-fetch queue of the length 16-bytes with extensive memory management capabilities. It is incorporated with the concept called “paging” in addition to the segmentation technique. It uses 80387 (math co-processor).
Intel introduced “80486” microprocessor with a built in mathematics co-processor and with a 1.2 million transistors. It could run at a clock speed i.e. 50 Megahertz. This is also a 32-bit processor but it is twice as fast as “80386”.The extra features in 80486 microprocessor is built-in Cache and built-in math’s co-processors. Because of presence of cache memory. The address bus here is bidirectional.
Intel released the Pentium-I Processor with 3.1 million transistors on 19th Oct, 1992.  So, the Pentium began as the fifth generation of Intel x86 architecture family. This was a backward compatible while offering new features. This revolutionary technology followed that the CPU is able to execute two instructions at a same time. This is known as super scalar technology. The data bus is 64 bits, however The Pentium uses a 32-bit expansion bus.
In 1997, Intel Pentium II processor was released.  It can works at a clock speed of 300Mega.Hz. Pentium 2nd uses the Dynamic Execution Technology which was consists of three different facilities namely

  1. Multiple branch prediction
  2. Data flow analysis, and
  3. Speculative execution unit

Another important feature of Intel Pentium 2nd is a thermal sensor located on the mother board which can monitor the die temperature of the processor. For the TMH (thermal management applications).
In the year 1999 the Intel family introduced Intel Celeron Processors. Pentium- 3 processor with 9.5 million transistors. It is a unique combination of multiple branch prediction, dataflow analysis and speculative execution. Pentium III uses dynamic execution micro-architecture. The Pentium-3 has improved processor serial number feature and MMX. The improved MMX enables advanced imaging, 3D (Three dimensional) streaming audio, video, and speech recognition for enhanced Internet facility.
In the year November 2000 Pentium-4 was introduced with 42 million transistors and 1.5 GHz clock speed was released by the Intel. The P4 (Pentium-4 processor) has a system bus with 3.2 G-bytes/second of bandwidth. This bandwidth is achieved with 64 –bit wide bus which is capable of transferring the data at a rate of 400 MegaHz. The P4 (Pentium 4 processor) enables real-time MPEG-2 video encoding and near real-time MPEG4 encoding, allowing the feature of
Efficient video editing and
Video conferencing
Intel and HP (Hewlett-Packard) developed the next generation 64-bit processor architecture called IA-64 .This is first implementation was named Itanium. In the year 2001 Itanium processor which is the first in a family of 64 bit products was introduced .The Itanium processor was designed specially to provide a very high level of parallel processing, to enable the high performance without requiring very high clock frequencies .Key strengths of the Itanium architecture is that This processor can handle up to 6 simultaneous 64 –bit instructions /clock cycle.
On July 8 year 2002, The Itanium II is an IA-64 microprocessor developed jointly by (HP) Hewlett-Packard and Intel and released .It is theoretically capable of performing nearly 8 times more work per clock cycle than other CISC and RISC architectures due to its parallel computing micro-architecture. The recent Itanium processor features a split L2 cache, adding a dedicated 1MB L2 cache for instructions and thereby effectively growing the original 256KBL2 cache, which becomes a dedicated data cache. The first Itanium II processor was more powerful than the original Itanium processor, with approximately 2 times performance.
Pentium 4E was released in the year 2004 and Pentium 4EE was released by Intel in the year 2003.
The 64 bit Intel Core2 was released on July 27 year 2006. The Pentium Dual-Core brand was used for mainstream X86-architecture microprocessors from Intel from 2006 to 2009. In the terms of features, price and performance at a given clock frequency, Pentium Dual-Core processors were positioned above the Celeron but below the Core and the Core 2 microprocessors in Intel’s product range. The Pentium Dual-Core was a very popular choice for over clocking, as it can deliver optimum performance at a low cost.
On January 21, year 2007, The Pentium Dual Core, which was consists of 167 million transistors was released. Intel Core Duo consists of 2 cores on a one die, a 2 MB L2 cache shared by both the cores, and an arbiter bus that controls both L2 cache and FSB access.
Core 2 Quad processors are the multi-chip modules consist of two dies those used in Core 2 Duo both are similar, forming a quad-core processor. While this allows twice the performance of dual-core processors at the same clock frequency in the ideal conditions, this is highly workload specific and requires applications to take advantage of the extra cores.
In September year 2009, Core i7 models based on the Lynnfield desktop quad-core processor and the Clarksfield quad-core mobile were added, and the models based on the Arrandale dual-core (mobile processor) announced. On March 16, 2010 The first six-core processor in the Core lineup was launched. The leading-edge Intel® Core™ i7 processor delivers unmatched technology for intelligent performance at the most demanding tasks, such as a playing intense games and creating digital video.
The Intel 8085 Microprocessor:
Intel 8085A is a single chip 8-bit N-channel microprocessor which works at +5V DC power supply. It is a 40 pin IC available as a DIP (Dual Inline Package) chip. 8085A can operate with a 3 Mega Hetz (MHz) single phase clock and 8085A-2 version can operate at a maximum frequency of 5 Mega HZ. This 8085 is an enhanced version of its predecessor the 8080A. Its instruction set is upward compatible with that of the 8080A. 8085A has an on-chip clock generator with external crystal, LC or RC network. This 8085 microprocessor is built with nearly 6200 transistors. The enhanced version of 8080 is the Intel 8085AH. It is an N channel depletion load, silicon gate (HMOS) 8-bit processor. Here 3Mega HZ, 5Mega HZ and 6Mega HZ selections are available. It has 20% lower power consumption than the 8085A microprocessor for 3Mega HZ and 5Mega HZ. Its instruction set is 100% software compatible with the 8085A and also 100% compatible with 8085A.