CPU and memory
Download as DOCX, PDF0 likes327 views
This document provides explanations of various components of a computer system including the CPU, ALU, control unit, memory unit, and cache memory. It describes the CPU as the brain of the computer that performs tasks like arithmetic, logical and I/O operations. The ALU is where data processing occurs through arithmetic and logical operations. The control unit controls operations in the CPU and directs traffic, synchronizing the entire system. The memory unit refers to both primary memory like RAM and ROM, as well as secondary memory for long-term storage.
CPU and memory
- 1. ASSIGNMENT#02 TITLE: EXPLANATIONOF CPU, ALU, MU, CU, REGISTER AND CACHEMEMORY COURSE: INTRODUCTIONTO COMPUTING STUDENT ID: CSC-17F-047 CLASS: BSCS SECTION: 1B SUBMITTED BY: SUBMITTED TO: WAJIHA M.ISMAIL SIR.AMEENKHUWAJA
- 2. CPU: CPU is the abbreviation of Central Processing Unit. Itis a brain of computer. Itis one of the leading part of computer, which brings the instructions to computer program. CPUdo multiple tasks like arthimethical, logical and input/output operations. Structureof CPU is changed by day’s promotion but it do the same operations. FirstCPU was introduced in 1940s which workswith first computer EDVAC(Electronic DiscreteVariable Automatic Computer). It have microprocessor, memory and motherboard. Logicalcoreis called a thread and multi core processor arecalled physicalcore. Multi core systemhavemore than one core,the common CPUs are dual coreand quad core. Multi core are those core which is a single computing components which independent on 2 or more processing units. MICRO-PROCESSOR: Itis IC(Integrated Circuit) that have milllions of transistors connected through the small aluminium wires. Ithaveprocessing abilities to control the PC through networking with an additional electronic modules on motherboard.
- 3. MOTHERBOARD: Itis a central PCB(Printed Circuit Board) in several modern computers and it hold severalof key components of system, which delivers connecter to other peripherals. Itis sometimes known as planar board, main board, systemboard, or on Apple computers it is known as logic board. ALU: ALU is the abbreviation of Arithmetic and Logic Unit. ALU is the place where data is processing. Itis a digital electronic circuit performs arithmetic and logic operations like addition, subtraction , shifting operation and logic operators Boolean comparison like AND, OR, XORand NOT operations. Itis made for integer calculations. ALUoften handle the multiplication, the resultis also an integer. ALU cannot performs thedivision becauseof their fraction results, it is performs by FPU (Floating Point Unit) which performs non-integer calculations. ALU is the essential structureblock of severalkinds of computing circuits with CPU (central processing unit), FPU (floating point unit), and GPU (graphics processing unit). A single CPU, FPU or GPU have many ALU. By John Von Neumann ALUidea in 1945 in a boom of foundation for a fresh computer known as EDVAC. ALU is the combinational logic circuit. Its outputwill transformasynchronously in reaction to input modifications. The outer circuit linked to the ALU is answerable for confirming the constancy of ALU input signals in the operations. Ithave two operations: fixed point and floating point. Italso have a complex operation in which its multiply two numbers and then add it.
- 4. ALU must practice number by the similar setup as the respite of digital circuit. On behalf of modern processor, this is constantly on the two balance binary numbers demonstration. Primary computer used a extensive variety of number systems, containing one’s complement, sign-magnitudeformat, and even true decimal system, with ten tubes per digit. ALUs for every one of these numeric systemhad dissimilar projects, and that inclined the current partiality for two’s complement, as this is the demonstration that creates it easier for the ALU’s to evaluate additions and subtractions. SYMBOL OF ALU: A and B is denoted to the input to ALU. R is denoted to the output or result. F is denoted to the code or the instructions which is fromthe controlunit. D is denoted to output status which indicates the cases.
- 5. CU: CU is the abbreviation of controlunit. Itis the circuit in the CPU, which controls the operations in the CPUand directing traffic in a sense. Control unit performtheir functions which depends on CPU types. The varying units of design among all the dissimilar CPUs will regulate the function of CU. Itcan hold altogether the processor controlsignals and nonstop all flows of input and output, fetches code for instructions frommicro-programs and also nonstop other units and models which providing by control and timing signals. Itdirects the signals to other portion of computer. It synchronizes thecomplete systemby significant devices what to do and when to do. Control unit was generally well-defined as one separateportion of 1946 link ideal of Von Neumann architecture. The function of controlunit is to create appropriatetiming and controlsignals to all processes in the computer. Control unit is the brain in the brain. Ithandles the movement of data among processor, memory and peripheral. The model of device needs control unit are CPU and GPU. Control unit leads the wholecomputer systemto carry out stored program instructions. Controlunit need to connect with both the ALU and main memory. Control unit coaches the ALU that which performs logicaland arithmetic operations. Control unit manage the actions of the other two units as well as all the peripherals and auxilary storagedevices connected to the computer. Itcontains two types. One is hardwired controlunit, which are implemented over use of sequential logic units or circuits like gate, filflops, decoders in hardware. It is normally faster than micro-programmed designs. Architectureis in reduced instruction set computer (RISC) as they used simpler instruction set. It contain of instruction register, no of control logic gates, two decoders, and 4-bit sequence counter. Second is micro-programmed controlunit, which wereprearranged as a sequence of micro-instructions and keptin different control memory. Outputof controller are prearranged in micro instructions and the can be easily substituted. Itis implemented using programming approach. Orders of micro operations are carried out by performing a program contain micro-instructions. Micro program containing of micro instructions is kept in a controlmemory in a control unit. Execution of micro instruction is answerablefor generation of a set of control
- 6. signal. It consistof next address generator, controladdress register, control memory, and controldata register. MU: MU is the abbreviation of Memory Unit. Memory states to the physical devices used to collection of programor data on a short-term and always basis for use in a computer or other digital electronic device. TYPES OF MEMORIES: There are two types of memories. PRIMARY MEMORY: Itcontains two types. One is RAM and second is ROM. RAM contains two types SRAM and DRAM. ROM contains three types PROM, EPROMand EEPROM. SECONDARY MEMORY: Itcontains two types. One is sequential (e.g. Magnetic Tape) and second is random-magnetic optical. MAIN MEMORY: Main memory is also known as primary memory. Memory is one of the very important parts of computer without it you cannot run the computer as all the programs to start our computer are installed in it, also it is volatile in nature i.e. it will store information till it is on and then after switching off it forgets everything it is only a temporary not permanent. There are two types of main memory. 1. Random Access Memory(RAM) 2. Read Only Memory(ROM)
- 7. RANDOM ACCESS MEMORY: Itstores data temporary. Itis volatile in nature. It stores initial, intermediate and final data of process. Thereare two types of RAM: 1. Static Memory 2. Dynamic Memory STATIC MEMORY: Itrefreshes itself on the command until it is commanded to refresh itself. It do not causeany type of delay in the process by refreshing itself. Itis costlier. Itis used in launching of rockets, wherethere is no place for even a fraction of delay in process. DYNAMIC MEMORY: Itrefreshes itself in every few milliseconds, to arrangeall the data and to make the full useof the processsor and process theas fastas possibleand also to utilize all the memory of the computer. Itis comparatively cheaper in price. Itis used in common PCs. READ ONLY MEMORY: Itstores data permanently. It is non-volatile in nature. It stores the code to run the computer, BIOS (Basic InputOutputSystem). Thereare three types of ROM: 1. ProgrammableROM 2. ErasablePROM 3. Electronically EPROM
- 8. PROGRAMMABLEROM: Itis use and throw ROM chip. If the programwritten in the chip is in use, it’s will work but soon as there need a change in the program, a new program will have to be written on other chip which creats a lot of pollution as it cannot be recycled . to solve this problemEPROM was invented. ERASABLEPROM: To avoid all the scrap produced by PROM, EPROM was invented. The programwritten in it can be erased by the action of ultra violet rays on the chip. The problem with it was that , by the action of UV rays on it, the chip was damaged, and could not be used after 2-3 times of erases and also if you want erase a little part of the program, it will remove all the data and you will have to startfrom the starting point. ELECTRICALLY EPROM: To resolvethe problem of EPROM, EEPROMwas invented, which can be erase the data electronically, then rewriting the programin it. If there has to be a little change in chip, the whole data is not to be erased, only the effective part can erased and rewritten on it. SECONDARY MEMORY: Primary memory has a limited storage capacity and not permanent. Secondary storagedevices are used to storelarge amount of data permanently. Itis not non-volatile in nature, it stores all the data permanently in it after the computer is turned off. There arevarious type of secondary memory. RANDOM MEMORY: Itconsistof two types: 1. Magnetic Form 2. Optical Form MAGNETIC FORM: Itis storageof data on medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to storedata and is a form
- 9. of non-volatile memory. The information is accessed using one or more read and writes heads. E.g. hard disk, floppy disk, recording etc. OPTICAL FORM: The compact disk are optical way to storing the information. The CDs are relatively very cheap and handle up to huge sumof input e.g. 70MBto 100GB. There are three types of CDs 1. CD-ROM(compactdisk read only memory) 2. CD-R(recordable) 3. CD-RW(rewritable) REGISTER: Register are used to rapidly accept, store, and transfer data and instructions that are used instantly by the CPU, there are various kinds of Registers those are used for various determination. Among of the some Mostly used Registersnamed as ACor Accumulator,Data Register or DR, theAR orAddress Register, programcounter (PC), MemoryDataRegister(MDR),Indexregister,Memor y Buffer Register. These Registers are used for performing the various Operations. While we are working on the System then these Registers are used by the CPU the Operations. for Performing When We Gives Some Input to the System then the Input will be Stored into the Registers and When the System will give us the Results after Processing then the Result will also be fromthe Registers. So that they are used by the CPU for Processing the Data which is given by the User. Registers Perform :- 1)FETCH: The Fetch Operation is used for taking the instructions thosearegiven by the user and the Instructions thosearestored into the Main Memory will be fetch by using Registers.
- 10. 2)DECODE: The Decode Operation is used for interpreting the Instructions means the Instructions aredecoded means the CPU will find out which Operation is to be performed on the Instructions. 3)EXECUTE: The Execute Operation is performed by the CPU. And Results those are produced by the CPU are then Stored into the Memory and after that they are displayed on the user Screen. Types of Registers are as Followings MAR STAND FOR MEMORY ADDRESS REGISTER This register holds the memory addresses of data and instructions. This register is used to access data and instructions from memory during the execution phase of an instruction. Suppose CPU wants to store some data in the memory or to read the data from the memory. Itplaces the address of the-required memory location in the MAR. Program Counter The programcounter (PC), commonly called the instruction pointer (IP) in Intelx86 microprocessors,andsometimescalled the instructionaddressregister,or justpart of the instruction sequencer in some computers, is a processor register It is a 16 bit special function register in the 8085 microprocessor.Itkeeps track of the the next memory address of the instruction that is to be executed once the execution of the current instruction is completed. In other words, it holds the address of the memory location of the next instruction when the current instruction is executed by the microprocessor.
- 11. ACCUMULATOR REGISTER This Register is used for storing the Results those are produced by the System. When the CPU will generate Some Results after the Processing then all the Results will be Stored into the AC Register. MEMORY DATA REGISTER (MDR) MDRis the register of a computer's controlunit that contains the data to be stored in the computer storage (e.g. RAM), or the data after a fetch from the computer storage. It acts like a buffer and holds anything that is copied from the memory ready for the processor to use it. MDR hold the information before it goes to the decoder. MDR which contains the data to be written into or readout of the addressed location. For example, to retrieve the contents of cell 123, wewould load the value 123 (in binary, of course) into the MAR and performa fetch operation. When the operation is done, a copy of the contents of cell 123 would be in the MDR. To store the value 98 into cell 4, we load a 4 into the MAR and a 98 into the MDR and performa store. When the operation is completed the contents of cell 4 will have been set to 98, by discarding whatever was there previously. The MDRis a two-wayregister.When data is fetched frommemoryand placed into the MDR, it is written to in one direction. When there is a write instruction, the data to be written is placed into the MDR from another CPU register, which then puts the data into memory. The Memory Data Register is half of a minimal interface between a micro program and computer storage, the other half is a memory address register. INDEX REGISTER A hardwareelement which holdsa numberthat can be added to (or,in somecases, subtractedfrom)the addressportionof a computer instructionto forman effective address. Also known as base register. An index register in a computer's CPU is a processor register used for modifying operand addresses during the run of a program. MEMORY BUFFER REGISTER MBR stand for Memory Buffer Register. This register holds the contents of data or instruction read from, or written in memory. Itmeans that this register is used to store data/instruction coming from the memory or going to the memory.
- 12. DATA REGISTER A register used in microcomputers to temporarily store data being transmitted to or from a peripheral device. CACHE MEMORY: A Cache is a minor and very fast short-term storage memory. It is aimed to speed up the transferenceof data and instructions. Itis situated inside or near to the CPU chip. It is faster than RAM and the data/instructions that are greatest freshly or greatest frequently used by CPU are kept in cache. The data and instructions are recovered from RAM when CPU uses them for the first time. A duplicate of that data or instructions is kept in cache. The next time the CPU requirements that data or instructions, it first looks in cache. If the essential data is establish there, it is recovered from cache memory in its place of main memory. It speeds up the functioning of CPU. Types/Levels of Cache Memory A computer can have numerous dissimilar levels of cache memory. The level numbers stateto distance fromCPUwhereLevel 1 is the closest. All levels of cache memory are faster than RAM. The cache next to CPU is constantly faster but normally costs more and stores less data then other level of cache. The following are the differentt levels of Cache Memory. Level 1 (L1) Cache Itis also knownprimaryorinternal cache. Itis madeopenly into the processorchip. It has small capacity from 8 Km to 128 Kb. Level 2 (L2) Cache It is slower than L1 cache. Its storage capacity is extra, i-e. From 64 Kb to 16 MB. The currentprocessors haveprogressivehandover cacheon processor chip that is a kind of L2 cache. The collective size of this cache is from 512 kb to 8 Mb.
- 13. Level 3 (L3) Cache This cache is unconnected from processor chip on the motherboard. It occurs on the computer that uses L2 progressivetransfer cache. It is slower than L1 and L2 cache. The personal computer frequently has up to 8 MB of L3 cache.