Informally, a microprocessor (µP) is the “brain” of a computer that has been implemented on one semiconductor chip.
More precisely, a microprocessor is a single-chip central processing unit (CPU) for a programmable computer.
A CPU may be considered to be the “brain” of a computer because it “understands” and “executes” the sequence of binary instructions in a compiled computer program.
Compared to the CPU, the other parts of a computer are relatively “dumb” and require detailed attention from the CPU in order to function properly in the computer system.
Applications of Microprocessors
Microprocessors can be found just about everywhere:
In general-purpose computers, like mainframes, personal computers (PCs), and single-board computers (SBCs).
In special-purpose computers, like calculators, personal data assistants (PDAs), and game computers.
In embedded computers that control automobiles, appliances, instruments, communication systems, cell phones, factories, assembly lines, refineries and etc.
Ex. In a car : Microprocessors are used in the ignition system, emission control system, anti-lock brakes, dashboard display, entertainment system, navigation system, etc. Modern cars often contain 20 or more microprocessors.
The microprocessor became possible only after integrated circuit technology had advanced to the point where several thousand transistor switches could be integrated onto a single semiconductor “chip”.
The Intel 4004 (1971) was the first microprocessor:
originally developed for a desktop calculator product
contained 2300 transistors
occupied a silicon area of 12 mm2
implemented in 10 µm PMOS semiconductor technology
data bus was 4 bits wide
640 bytes of data could be addressed
system clock run at a frequency of 108 KHz
could perform roughly 60000 operations per second
Microprocessors History (cont.) Intel 4004 Was Intel's first microprocessor. It contained 2,300 transistors and was built using a 10 micron process. It had a total of 16 pins.
Microprocessors History (cont.)
The Intel Itanium entered mass production in 2001:
intended for high-end servers and workstations
contains 25.4 million transistors
silicon chip area exceeds 300 mm2
180 nm CMOS semiconductor technology
6 layers of metal interconnections
1012 chip pad connections
64-bit data bus; 64-bit address bus; 64-bit registers
memory space of over 18 terabytes (264 = 18.45 x 1018).
system clock frequency of at least 800 MHz
peak performance of 3.2 billion instructions per second
The pace of technological progress shows no signs of slowing down in the immediate years ahead . . .
Microprocessors History (cont.) Pentium 4 42 million transistors and circuit lines of 0.18 microns. Intel's first microprocessor, the 4004, ran at 108 kilohertz (108,000 hertz), compared to the Pentium 4 processor's initial speed of 1.5 gigahertz (1.5 billion hertz).
The appearance of the microprocessor revolutionized digital system design starting in the 1970s, and continuing on until the present day.
The main advantages of the microprocessor:
Programmability: Sophisticated functions can be provided relatively easily in software.
Performance: Advances in integrated circuit technology are leading to faster and more “powerful” microprocessors.
Cost-effectiveness: Microprocessors, because they are multi-purpose, are manufactured in large quantities, which tends to minimize their unit cost.
Reliability: Integrated circuits are highly-reliable, solid state devices. Microprocessors have no moving parts.
Compactness: More and more functionality can be packed onto a single microprocessor/microcontroller chip.
Basic Microprocessors System Input Devices Processing Data into Information Output Devices Control Unit Secondary Storage Devices Arithmetic- Logic Unit Primary Storage Unit Central Processing Unit Keyboard Mouse Touch Screen Voice... Monitor Printer Disks, Tapes, Optical Disks
Basic Microprocessors System (cont.)
A basic microprocessor system consists of the microprocessor core, memory, input/output modules, and a system bus connecting these modules.
The memory system usually consists of Read Only Memory (ROM) for boot information, and Random Access Memory (RAM) organized in a hierarchy of main memory and multilevel cache memory.
Typically, the cache memory is implemented as level 1 cache closely coupled to the microprocessor core, and level 2 cache accessible over the system bus.
The main memory, typically DDR SDRAM, is accessible over the system bus as well, but level 2 cache (embedded SRAM) offers higher access speed.
Basic Microprocessors System (cont.)
The microprocessor core contains a datapath section (ALU and registers), a control section, and cache memory.
Memory access rate varies according to the memory hierarchy from 1 cycle access rate to registers and level 1 cache, to 10 cycles access rate to level 2 cache, up to 50 cycles access rate to main memory.
These are typical values and may vary from system to system.
Type Of Microprocessors
Computers based on a CPU with a complex instruction set known as CISC (Complex Instruction Set Computer) microprocessor
A RISC (Reduced Instruction Set Computer) has limited set of instructions that it can perform quickly
The Embedded Processor
A programmable processor whose programming interface is not accessible to the end-user of the product.
The only user-interaction is through the actual application.
Sharp PDA’s are encapsulated products with fixed functionality.
3COM Palm pilots were originally intended as embedded systems. Opening up the programmers interface turned them into more generic computer systems.
Disadvantages of Microprocessors
Microprocessors have many complex features. Numerous features are provided to satisfy a wide variety of users.
Microprocessors are completely unforgiving when program errors are made. They will execute exactly what is in the program, and have no “common sense” or “intuition” about what the designer intended the program to do.
Debugging tools for microprocessor assembly language programs are usually primitive compared to the tools available for programs in high-level languages.
Microprocessors Related Terms
A “microcomputer” is a computer system that has been built around a microprocessor chip.
A “microcontroller” is an integrated circuit that contains a microprocessor as well as other useful support circuits, such at timers, memory, input/output interface circuits, etc.
The EE380 lab microcomputer system contains the Motorola MC68332 microcontroller chip.
A “digital signal processor” (DSP) is a specialized microprocessor that has features (e.g. instructions, registers, internal signal paths, arithmetic circuits) that make it particularly efficient at performing the kinds of numerically intensive calculations that are required in digital signal processing (e.g. in modems and cell phones)
Microprocessor manufacturers tend to release microprocessors in families of increasing complexity and performance
4004 (1971), 8008 (‘72), 8080 (‘74)
x86 family : 8086 (‘78), 8088 (‘79), 80186 (‘82), 80286 (‘82), 80386 (‘85), 80486 (‘89), Pentium (‘93), Pentium II (‘97), Pentium III (‘99), Pentium 4 (2000), Xeon (2001)
IA-64 family: Itanium (2000),
6800 family : 6800 (1974), 6809 (‘79), 68HC11 (‘84)
M68000 family : 68000 (1979), 68010 (‘82), 68020 (‘84), 68030 (‘87), 68040 (‘89), 68332 (‘89), Power PC
Microprocessor families make it easier to carry software over from an older µP to the latest µP. “Upward compatibility” is an important strategy for building customer loyalty.