1. Introduction to Microprocessors
CHAPTER 2
Introduction to Microprocessors
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2. History of Microprocessors
The CPU on a single chip was named a microprocessor (µP).
Microprocessor
Process technology
Year
Intel 4004
10 µm
1971
Intel 8085
03 µm
1975
Intel 80286
1.5 µm
1982
Intel 80386
1.0 µm
1985
Intel 80486
0.8 µm
1989
Intel Pentium Pro
AMD K5
350 nm
1995
Intel Pentium IV AMD Athelon XP
130 nm
2002
Intel Xeon
AMD Athelon 64
90nm
2004
Intel Core 2
IBM Z10
65nm
2006
Intel i3, i5
AMD FX
32nm
2010
Intel Core i7
14nm
2015
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3. Microprocessor Fundamentals
A complete CPU fabricated on a single chip is called a microprocessor (µP).
The IC chip and block diagram for a typical microprocessor
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4. The Processing Power of a Microprocessor
The processing power of a microprocessor depends upon its word size. The word size is measured in terms of the number of bits, in multiples of 2. Accordingly the microprocessors are called bit µP, 16-bit µP, 64-bit µP etc.
Generally, the size of internal registers of a microprocessor is same as or is in multiples of the word size.
Therefore, an 8-bit microprocessor can process 8-bit data at a time and the 64-bit microprocessor can process 64-bit data at a time.
Obviously, the 64-bit microprocessor is almost four times faster than an 8-bit microprocessor.
Since the data is transported to and from memory through a data bus, the size of the data bus is also the same as or is in multiples of word length.
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5. Word Length of Microprocessors
(bit)
Intel 8085 8
8086 16
80386 32
80486
Pentium 64
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6. Computer Fundamentals and Programming in C
BUSES
The data bus is a bidirectional group of lines on which the data can travel both ways, i.e., from a microprocessor to a device and vice versa.
The address bus is a unidirectional group of lines on which address of a memory location or a device is sent by the microprocessor.
The control bus is a group of lines on which control signals flow from the microprocessor to the connected devices and vice versa. Examples of control signals are ‘memRead’, ‘memWrite’, ‘ioRead’, ‘ioWrite’, ‘reset’, etc.
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7. Computer Fundamentals and Programming in C
Memory Read Operation
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8. Memory Write Operation
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9. Processor Design Types: CISC and RISC
S. No.
CISC
RISC 1
Large number Instructions
Reduced number Instructions 2
Lesser number of general purpose
registers i.e. 8–10 registers
Large number of general purpose
registers i.e. 32–35 registers 3
Variable instruction length
Uniform instruction length 4
Compilers are hard to write
Compilers are simple to write 5
Program size is small
Program size is large 6
Processor is difficult to design
Processor is easier to design 7
High cost
Low cost
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10. Generations of Microprocessors
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11. First Generation Microprocessors
After Intel 8085, Intel developed the 8086 chip with a clock speed of 4.77MHz.
This 1st generation microprocessor had a 16-bit data bus and 20-bit address bus, capable of addressing 1 MB of RAM. In order to increase the computational efficiency of the 8085 microprocessor, Intel developed the 8087, another chip called Maths processor.
It was a specially designed processor to carry out floating point calculations at a much faster rate than the 8086 chip. Thereafter, applications such as word processors, spreadsheets, animation software etc. became faster.
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12. Second Generation Microprocessors
Intel produced the chip as a 2nd generation microprocessor with a 16-bit data bus, 24-bit address bus, and 6-20 MHz clock speed.
It was very widely used for multitasking applications.
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13. Third Generation Microprocessors
Intel 80386, and were developed as 3rd generation microprocessor and coprocessor respectively. The had 32-bit data as well as address bus, capable of addressing 4 GB of RAM. The clock speed varied from 16–33 MHz.
In the meantime, Microsoft developed the Windows operating system which was designed to harness the complete power of a 32-bit microprocessor such as
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14. Fourth Generation Microprocessors
Intel was the 4th generation microprocessor with a 32-bit data bus as well as address bus. The clock speed varied from 25 MHz to 33 MHz. No separate co-processor was developed; the maths processor was integrated onto the chip itself.
The second important feature was that a small cache memory of 8 KB was also included on the chip with a view to increase the performance of the chip.
The third important development was that in the fourth generation microprocessors, Intel provided an internal clock multiplier that could enhance the clock speed of the processor by 2X and 4X and accordingly the chips were named as 484DX2 and 486DX4 respectively. In fact, the 486DX4 had a wide variety of clock speeds: 25, 33, 50, 66, 75, and 100 MHz.  
It was a pipelined processor wherein the operations like instruction fetching, decoding, execution, memory access, and writing back the results were performed in parallel, of course, for different instructions.
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15. Fifth Generation Microprocessors
Till the 3rd and 4th generation microprocessors, Intel shared its µP technology with companies like AMD and IBM. Due to copyright problems, Intel named its 5th generation microprocessor Pentium instead of the conventional 80586, though Pentium also means five. The Pentium was designed by Vinod Dham, an electronics engineer from India.
Pentium, a CISC processor, had data and address buses of size 64 and 32 bits respectively. The initial versions of Pentium had clock speed 33 Mz, 60 Mz, 66 Mz. With the help of internal 1.5 multipliers, the speed was increased to 90 and 100 Mz. Later on, Pentium with 133, 166, and 200M z were also introduced.
In 1997, Intel added 72 new instructions to enhance multi-media computing and the chip was accordingly called Pentium MMX.
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16. Sixth Generation Microprocessors
Intel produced the Pentium pro as a 6th generation microprocessor. This processor was designed to have a RISC core. An internal circuit was used to convert CISC instructions to RISC instructions
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17. Pentium Pro Microprocessor
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18. Computer Fundamentals and Programming in C

19. Seventh Generation Microprocessor
AMD Athelon K7, Intel Pentium IV, and Alpha are the 7th generation microprocessors.
Pentium PIV onwards, Intel used the concept of ‘hyperthreading’ where it allows parallel parts of a process to execute in parallel on the microprocessor.
Since the parallel parts of a process are called threads, the process is called a threaded process and the phenomenon is called multithreading. It is highly suitable for multitasking applications.
The clock speed ranges from 2.4 Ghz to 3.2 Ghz. The AMD FX is also a hyperthreading microprocessor.
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20. Eighth Generation Microprocessors
Intel Itanium, Itanium-2 and AMD Athelon 64 are 8th generation 64-bit microprocessors.
Intel Itanium 2 has a 1.4 GHz clock speed and 1.5 MB L3 cache.
Besides Itanium, Intel has also produced other very powerful microprocessors called the Intel Xeon 3.20 GHz processor with 1 MB integrated cache.
Xeon processors are intelligent server processors. These are being used for high-end workstations and enterprise servers.
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21. Recent Trends in Microprocessor Architecture
A typical microprocessor consists of following components:
Control Unit (CU)
Arithmetic and Logic Unit (ALU)
Register Array
System Bus
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22. Computer Fundamentals and Programming in C
A Single Core CPU
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23. Multicore Microprocessor
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24. Intel Core I7 Cache Hierarchy
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25. Computer Fundamentals and Programming in C
Motherboards  
A Motherboard, also known as a system board, is a printed circuit board that contains most of the essential electronic components of the computer system.
It contains a socket into which the microprocessor is plugged in. Besides the microprocessor, the motherboard has a cluster of chips called a chipset, present on the board.
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26. Computer Fundamentals and Programming in C
CPU Interface 
This interface is used to connect the CPU to the motherboard.
The interface present on the motherboard decides as to which microprocessor or family of microprocessors can be plugged to the motherboard.
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27. Computer Fundamentals and Programming in C
Front Side Bus
A front side bus (FSB) connects the CPU with the motherboard chipset and the main memory.
The commonly available speed of the FSB is in the range of 66–800 MHz.
The speed of the FSB is very important because the maximum speed at which the main memory can interact with CPU is the FSB speed.
If the FSB transfers 64 bits of data (8 bytes) at 800 MHz, then the data transfer rate is (800 * 8) 6400MBps.
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28. Computer Fundamentals and Programming in C
Chipset 
A chipset is a cluster of IC chips present on the motherboard to control basic devices such as hard disks, floppy disks, serial/parallel ports etc.
The chipset also controls the information flow from one component of the motherboard to another.
A chipset is specific to a processor and therefore, the motherboard with a specific chipset can support only a compatible processor on board.
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29. BIOS chips (Basic Input/Output System)
BIOS stands for Basic Input/Output System.
BIOS is a set of program instructions capable of interacting with the standard input/output devices attached to a computer system.
The boot-up information is also stored in the BIOS chips.
When the system is switched on, the BIOS starts executing.
The BIOS checks the status of the connected devices through a test called ‘Power-On Self-Test’ (POST).
Thereafter, based on boot-up information contained on the BIOS chip, BIOS loads the operating system from one of the attached devices.
By construction, a BIOS chip is a PROM (Programmable Read-Only Memory).
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30. Computer Fundamentals and Programming in C
RAM Chips
The main memory attached to the motherboard is called the RAM, which comes in many types.
RAM is available as SDRAM, EDRAM, RDRAM, etc.
The size of RAM varies from 64 MB to 4 GB and beyond.
The speed of the RAM chip should be as high as possible for better performance of the computer system.
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31. Computer Fundamentals and Programming in C
Hard Disk Controller
The secondary storage devices are connected to the motherboard through IDE (Intelligent Device Electronics) and FDD (Floppy Disk Drive) connectors provided on the board.
The IDE connector has 40 pins through which the following IDE devices can be attached
Hard disk drives
High-density disk drives
CD-ROM/DVD drives
Similarly, Floppy drives are connected to the motherboard through a 34-pin connector.
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32. Computer Fundamentals and Programming in C
Expansion Slots
Peripheral devices are connected to the motherboard through expansion slots called PCI (Peripheral Connect Interface) slots.
For instance, sound cards and graphic cards, gaming cards, network cards are plugged to the motherboard’s available standard 32-bit PCI slots.
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33. Computer Fundamentals and Programming in C
USB Ports 
Universal Serial Bus (USB) has become an industry standard to connect peripheral devices to the computer system.
Therefore, a motherboard supports more than one USB port to which devices such as keyboard, printers, scanners, PenRam, mouse etc. are connected in ‘plug-n-play’ mode.
A USB port is a 5-pin connector.
The operating system detects a device as soon as it is plugged to the USB port of the computer system.
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