Basic Components Of Microcomputer PDF

BASIC COMPONENT OF MICROCOMPUTER 1. CPU - Central Processing Unit The portion of a computer system that carries out the instructions of a computer program The primary element carrying out the computer's functions. It is the unit that reads and execu...

BASIC COMPONENT OF MICROCOMPUTER 1. CPU - Central Processing Unit The portion of a computer system that carries out the instructions of a computer program The primary element carrying out the computer's functions. It is the unit that reads and executes program instructions. The data in the instruction tells the processor what to do. Pentium D dual core processors 2 2. Memory Physical devices used to store data or programs. Computer main memory comes in two principal varieties: random-access memory (ram) and read-only memory (rom). Ram can be read and written to anytime the cpu commands it, but rom is pre-loaded with data and software that never changes, so the cpu can only read from it. Rom is typically used to store the computer's initial start-up instructions. In general, the contents of ram are erased when the power to the computer is turned off, but rom retains its data indefinitely. In a pc, the rom contains a specialized program called the bios that orchestrates loading the computer's operating system from the hard disk drive into ram whenever the computer is turned on or reset. 3 3. I/O Unit Input/output (I/O), refers to the communication between an information processing system (such as a computer), and the outside world possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it Devices that provide input or output to the computer are called peripherals On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O. 4  ARITHMETIC AND LOGIC UNIT (ALU) The component that performs the arithmetic and logical operations the most important component in a microprocessor and is typically the part of the processor that is designed first. able to perform the basic logical operations (AND, OR), including the addition operation. 5 Crashcourse.com  Semiconductor Memory Storage device in microcomputer where instructions and data are stored in binary format To retrieve information, the microcomputer assigns addresses to the location Each address stores one byte 1 byte = 8 bits 1 word = 2 bytes = 16 bits 1 longword = 2 words = 4 bytes = 32 bits 1 nibble = 4 bits Total location is 2N (N is address bus) Semiconductor Memory Some typical semiconductor memory ROM (read only memory) Nonvolatile storage Masked ROM, flash memory RAM (random access memory) Volatile, read and write https://www.youtube.com/watch?v=R5iHUyNPMt Static and dynamic RAM U&t=51s  CONTROL UNIT The circuitry that controls the flow of information through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC. On a regular processor, the control unit performs the tasks of fetching, decoding, managing Pi.interest execution and then storing results. 8 Types of Computers Computers can be generally classified by size and power Microcomputer / Personal computer A small, single-user computer based on a microprocessor Use personal computers for word processing, accounting, desktop publishing, running spreadsheet and database management applications, for playing games, and recently for surfing the Internet. Examples are desktop computers, laptops, netbooks, handheld computers/ palmtop/ pocket computers, tablets and smartphones.  Types of Computers Minicomputer A multi-user computer capable of supporting up to hundreds of users simultaneously It is a midsize computer and in general, a minicomputer is a multiprocessing system capable of supporting up to 200 users simultaneously Minicomputers are used by small businesses & firms It’s believed that Karpiński paved the way for today’s These are small machines and can be common use of paging in computer memory systems. On top of all this the K-202, running on Karpiński’s accommodated on a disk with not as many original operating system, could have various processing and data storage capabilities as peripheral devices connected to it: a camera, a super-computers & Mainframes. printer, even radar. The computer was a multi- Use for specific purposes such as for purpose device – it could’ve been used in an office or for engineering work. It was also very reasonably monitoring certain production processes. priced but, most importantly, its system unit, the Examples are K-202 Texas Instrument TI- case containing the system’s bowels that was connected to an external monitor and keyboard, 990, SD-92, and IBM Midrange computers. could fit into a briefcase, just as Karpiński had promised. https://culture.pl/en/article/jacek-karpinski-the- computer-genius-the-communists-couldnt-stand  Types of Computers Workstation Use for engineering applications (CAD/CAM), desktop publishing, software development, and other types of applications that require a moderate amount of computing power and relatively high-quality 3- D graphics capabilities. Large, high-resolution graphics screen, a large amount of RAM, built- in network support, and a graphical user interface. The most common operating systems for workstations are UNIX and Windows NT Single-user computers and normally are typically linked together to form a LAN Excellent OS with high-speed speed RISC-processor SPARC-10, DEC, Silicon Graphic Types of Computers Mainframe Large computers are normally used for business by many large firms and government organizations. Not as powerful as supercomputers but must be accommodated in large air- conditioning rooms because of their size. Like supercomputers, mainframes can also The IBM mainframe – Ars Technica process and install large amounts of data. Educational institution and insurance companies use mainframe computers to store data about their customers students and insurance policyholders. Popular mainframe computers are Fujitsu’s ICL VME and Hitachi’s Z800  Types of Computers Supercomputer High speed for high position calculation with a combination of thousands of processes using parallel processing technique. The fastest and the most expensive computers with a typical supercomputer can do up to ten trillion individual calculations every second. Used to solve very complex science and engineering problems Use in many films such as space exploration, earthquake studies, natural sources, exploration weather forecasting, nuclear weapon testing, weapon simulation et cetera. The difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently. Examples are Tianhe -2 Titan – Cray XK7, Cray Inc. Sequoia – BlueGene/Q, IBM, K Computer TechCrunch Tofu Interconnect Fujitsu Mira – BlueGene/Q, Custom IBM μP vs μC Advantages of Microcontroller Advantages of Microprocessor High integration with small space for Offer high performance PCB Cost is much cheaper Very flexible and can easily be upgraded Special architecture and features Large size of memory Low power consumption Unlimited number of I/O More reliable due to less connection The system design is simple and flexible Reduce the design time due to less connection (internal design) Faster in speed of execution as the microcontroller of are fully integrated High Level Language  The syntax is similar to English.  A compiler is required to translate the program.  Allows user to work on the program logic at higher level.  Examples: C++ C PASCAL OMNET++ JAVA  Microprocessor Microprocessor (P) is the “brain” of a computer that has been implemented on one semiconductor chip. The word comes from the combination micro and processor. Processor means a device that processes whatever (binary numbers, 0’s and 1’s)  To process means to manipulate. It describes all manipulation.  Micro - > extremely small 1 6  Microprocessor ? A microprocessor is multi programmable clock driven register based semiconductor device that is used to fetch , process & execute a data within fraction of seconds. 1 7 GENERATION OF PROCESSORS Processor Bits Speed 8080 8 2 MHz 8086 16 4.5 – 10 MHz 8088 16 4.5 – 10 MHz 80286 16 10 – 20 MHz 80386 32 20 – 40 MHz 80486 32 40 – 133 MHz 1 8 GENERATION OF PROCESSORS Processor Bits Speed Pentium 32 60 – 233 MHz Pentium Pro 32 150 – 200 MHz Pentium II, 32 233 – 450 MHz Celeron, Xeon Pentium III, 32 450 MHz –1.4 GHz Celeron, Xeon Pentium IV, 32 1.3 GHz –3.8 GHz Celeron, Xeon Itanium 64 800 MHz – 3.0 GHz 1 9  A Microprocessor has many components like transistors, registers, and diodes which come together to perform. The ability of the chip has become more complex with technology evolution. The functionality has become better The speed has become faster Microprocessor Task There are three steps that a microprocessor follows – 1. Fetch – The instructions are in storage from where the processor fetches them. 2. Decode – It then decodes the instruction to assign the task further. During this, the arithmetic and logic unit also performs to register the data temporarily. 3. Execute – The assigned tasks undergo execution and reach the output port in binary form. 1st Generation – 4bit Microprocessor  Introduced in 1971. Intel 4004  It was the first microprocessor by Intel.  It was a 4-bit µP.  Its clock speed was 740KHz.  It had 2,300 transistors.  It could execute around 60,000 instructions per second.  For simple arithmetic and logical operations.  A control unit there used to 22  5th Generation – 64bit IMicroprocessors NTEL PENTIUM III  Introduced in 1999.  It was also 32-bit µP.  Its clock speed varied from 500 MHz to 1.4 GHz.  It had 9.5 million transistors. Status Register Bit Description T Tracing for run-time debugging S Supervisor or User mode I System responds to interrupts with a level higher than I X Retains information from carry bit for multi precision arithmetic N Set if the result is most significant bit (MSB) is set Z Set if the result is zero V Set if a signed overflow occur C Set if a carry or borrow is generated 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 T S I2 I1 I0 X N Z V C 25 4) INSTRUCTION SET The 68000 has a 16-bit status register. The upper 8 bits is the system byte, and modification of it is privileged. The lower 8 bits is the user byte, also known as the condition code register (CCR), and modification of it is not privileged. The 68000 comparison, arithmetic, and logic operations modify condition codes to record their results for use by later conditional jumps. The condition code bits are "carry" (C), "overflow" (V), "zero" (Z), "negative" (N) and "extend" (X). The "extend" (X) flag deserves special mention, because it is separate from the carry flag. 26 5) PRIVILEGE LEVELS The CPU, and later the whole family, implements two levels of privilege. User mode gives access to everything except privileged instructions such as interrupt level controls. Supervisor privilege gives access to everything. An interrupt always becomes supervisory. The supervisor bit is stored in the status register, and is visible to user programs. An advantage of this system is that the supervisor level has a separate stack pointer. This permits a multitasking system to use very small stacks for tasks, because the designers do not have to allocate the memory required to hold the stack frames of a maximum stack-up of interrupts. 27 6) INTERRUPTS The CPU recognizes seven interrupt levels. Levels 1 through 5 are strictly prioritized. That is, a higher-numbered interrupt can always interrupt a lower- numbered interrupt. In the status register, a privileged instruction allows setting the current minimum interrupt level, blocking lower or equal priority interrupts. For example, if the interrupt level in the status register is set to 3, higher levels from 4 to 7 can cause an exception. Level 7 is a level triggered non-maskable interrupt (NMI). Level 1 can be interrupted by any higher level. Level 0 means no interrupt. The level is stored in the status register, and is visible to user-level programs. 28  Programming Model Summary ▰ Status Registers: A 16-bit register circuit used by the CPU to indicate the condition/state of the microprocessor or known the Condition Code Register/ Flag Register. ▻ Bit-0: Carry Flag (C)  1 if arithmetic operation results in a carry/borrow ▻ Bit-1: Overflow Flag (V)  1 if arithmetic operation results in an overflow / error ▻ Bit-2: Zero Flag (Z)  1 if arithmetic/ logic operation result is zero ▻ Bit-3: Negative Flag (N)  1 if arithmetic operation results in a negative value ▻ Bit-4: Extend Flag (X)  Similar to Carry Flag ▰ Program Counter: A 24-bit counter circuit used to monitor the instruction line of a program 29 Data Transfering Technique (DTT) Three techniques are possible for I/O operations: Direct Transfer Interrupt Direct Memory Access 30 Direct Transfer / Programmed I/O Also known as Programmed I/O. A program controls the I/O Operation; hence CPU is fully involved. With Programmed I/O, data are exchanged between the CPU and I/O module. The CPU executes a program that gives it direct control of the I/O operation. When the CPU executes an instruction relating to the I/O, it issues a command to the appropriate I/O module. The CPU periodically checks the status of the I/O module until it finds the I/O operation is complete. 31 Direct Transfer… cont’d Programmed I/O takes place when an instruction in the program performs the data transfer; for example: MOVE.B Keyboard,D0 - to read a byte of data from the keyboard and puts it in D0. Some microprocessors have special instructions that are used only for I/O; for example: OUT 50 32  Interrupt A computer executes instructions sequentially unless a jump or a branch is made. An interrupt is a process or a signal that stops a microprocessor/ microcontroller from what it is doing so that something else can happen. In other words an interrupt is defined as a break in the normal flow of operation of a computer caused by an interrupt signal. An interrupt may be a signal from a peripheral (i.e., a hardware interrupt) or an internally-generated call to the operating system (i.e., a software interrupt). 33 Sources of Interrupt Internal fault (e.g. divide by zero, overflow) Software External hardware Maskable: An Interrupt that can be disabled or ignored by the instructions of the CPU is called a Maskable Interrupt. For example: Maskable interrupts used to interface with peripheral devices. Non-Maskable: An interrupt that cannot be disabled or ignored by the instructions of the CPU is called a Non-Maskable Interrupt For example, a non-maskable interrupt is used for emergency purposes, e.g. power failure, smoke detector, etc. RESET 34 Cont.. ▰ Hardware interrupts: every keystroke generates an interrupt signal. Interrupts can also be generated by other devices, such as a printer, to indicate that some event has occurred. ▰ Software interrupts: Interrupt signals initiated by programs. Exceptions belong to a special type of software interrupt. They are generated by the processor itself whenever some unexpected critical event occurs. ▻ Three types of exceptions: faults, traps, and aborts. 35 Direct Memory Access (DMA) Direct Memory Access (DMA) is where a device is allowed to take over the main computer bus from the CPU and transfer bytes directly to main memory. Normally the CPU would make a transfer from a device to the main memory in a two - step process: 1. Reading a chunk of bytes from the peripheral device and putting these bytes into the CPU 2. Writing these bytes from the CPU to the main memory 36 Cont.. With DMA it's a one - step process of sending the bytes directly from the device to memory. moves data between a peripheral and the CPU's memory without the direct intervention of the CPU itself DMA provides the fastest possible means of transferring data between an interface and memory, as it requires no CPU overhead and leaves the CPU free to do useful work. While DMA is going on, the CPU can't do too much since the main bus is being used by the DMA transfer. 37  DMA Operation DMA works by grabbing the data and address buses from the CPU and using them to transfer data directly between the peripheral and memory. During normal operation of the computer, bus switch 1 is closed, and bus switches 2 and 3 are open. The CPU controls the buses, providing an address on the address bus and reading data from memory or writing data to memory via the data bus. When a peripheral wishes to take part in an I/O transaction it asserts the TransferRequest input of the DMA controller (DMAC). 38 … cont’d In turn, the DMA controller asserts DMA requests to request control of the buses from the CPU; that is the CPU is taken offline. When the CPU returns the DMAgrant to the DMAC, a DMA transfer takes place. Bus switch 1 is opened and switches 2 and 3 are closed. The DMAC provides an address to the address bus and hence to the memory. At the same time, the DMAC provides a TransferGrant signal to the peripheral that is then able to write to, or read from, the memory directly. When the DMA operation has been completed, the DMAC hands back control of the bus to the CPU. 39