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  1. 1. 1.How are a computer's internal components physically linked? Illustrate the concept by describing a complete machine cycle.<br />MACHINE CYCLE Instruction Time (I-time)The instruction control unit fetches the next instruction from memoryThe address of the next instruction is found in the instruction counterThe instruction control unit extracts this address and sends it over the bus to the memory controllerThe memory controller accepts the command, reads the requested memory location and copies its contents onto the bus.The current instruction moves over the bus and into the instruction registerMACHINE CYCLE IN I-TIME1. The instruction control unit sends a fetch command over the bus to memory.2. Memory responds by copying the contents of the requested memory location onto the bus.3. The instruction moves into the instruction register.Execution Time (E-time)<br /> The ICU activates the arithmetic and logic unit.The ALU executes the instruction in the instruction register.The ALU issues, over the bus, a command to fetch the contents of a specified memory location.<br /> The memory controller reads the requested word and copies the contents onto the bus.The data flow to a work register.<br />2. On most computers, all internal components are designed around a common wordsize. Why? Explain how a computer wordsize affects its processing speed, memory, capacity, precision, and instruction set size.On most systems, the internal components are designed around a common word size. For example, on a 32-bit computer, the processor manipulates 32-bit numbers, memory and the registers store 32-bit words, and data and instructions move between the components over 32-bit bus lines.A computer’s word size affects its processing speed, memory capacity, precision, and instruction set size. Consider speed first. A 32-bit bus contains 32 wires, and thus can carry 32 bits at a time). The bigger the word size, the faster the computer.Memory capacity is also a function of word size.On a 32-bit machine, a 32-bit address can be transmitted. The biggest 32-bit number is roughly 4 billion in decimal terms, so the process can access as many as 4 billion different memory locations. The bigger its word size, the more memory a computer can access.There are 16-bit microcomputers that access considerably more than 64k bytes of memory, if addresses are broken into two or more parts and transmitted during successive machine cycles so memory capacity is gained at the expense of processing speed.Next, consider the size of the numbers each machine can manipulate. Registers generally hold one word. The processor’s internal circuitry is usually most efficient when manipulating numbers one word in length. A 32-bit mainframe adds 32-bit numbers; a 16-bit machine adds 16-bit numbers. Clearly, the machine with the bigger word size is more precise.216 64k<br />3) Computer architectureIn computer science and computer engineering, computer architecture or digital computer organization is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the central processing unit (CPU) performs internally and accesses addresses in memory.It may also be defined as the science and art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals.Computer architecture comprises at least three main subcategories:[1]Instruction set architecture, or ISA, is the abstract image of a computing system that is seen by a machine language (or assembly language) programmer, including the instruction set, word size, memory address modes, processor registers, and address and data formats. Microarchitecture, also known as Computer organization is a lower level, more concrete and detailed, description of the system that involves how the constituent parts of the system are interconnected and how they interoperate in order to implement the ISA.[2] The size of a computer's cache for instance, is an organizational issue that generally has nothing to do with the ISA. System Design which includes all of the other hardware components within a computing system such as: 1.System interconnects such as computer buses and switches 2.Memory controllers and hierarchies 3.CPU off-load mechanisms such as direct memory access (DMA) 4.Issues like multiprocessing. Once both ISA and microarchitecture have been specified, the actual device needs to be designed into hardware. This design process is called implementation. Implementation is usually not considered architectural definition, but rather hardware design engineering.Implementation can be further broken down into three (not fully distinct) pieces:Logic Implementation — design of blocks defined in the microarchitecture at (primarily) the register-transfer and gate levels. Circuit Implementation — transistor-level design of basic elements (gates, multiplexers, latches etc) as well as of some larger blocks (ALUs, caches etc) that may be implemented at this level, or even (partly) at the physical level, for performance reasons. Physical Implementation — physical circuits are drawn out, the different circuit components are placed in a chip floorplan or on a board and the wires connecting them are routed. <br />4 . Discuss the ff: terms: Motherboard, slot, bus, network, signal, local area network, wide area network, network server, workstation, hostA. MOTHERBOARD <br /> is the central printed circuit board (PCB) in many modern computers and holds many of the crucial components of the system, while providing connectors for other peripherals. The motherboard is sometimes alternatively known as the main board, system board, or, on Apple computers, the logic board.It is also sometimes casually shortened to mobo.B. SLOTS <br /> Slots are often called expansion slots because they allow you to expand the capabilities of a computer. C. BUS <br /> The bus refers to the paths between the components of a computer. The data bus and the address bus are two main buses in a computer which are located on the motherboard.• The data busIt is an electrical path that connects the CPU, memory, and the other hardware devices on the motherboard. Indeed, the bus is a group of parallel wires. Besides, the number of wires in the bus affects the speed at which data can travel between hardware components. Each wire can transfer one bit at a time. If it is eight – wire bus, it can move eight bits at a time or a full byte. Thus, the width of the data bus determines how many bits at a time can be transmitted between the CPU and other devices.• The address busThe second bus that is found in every microcomputer is the address bus. It is a set of wires similar to the data bus that connects the CPU and RAM and carries the memory addresses. The reason of the address bus is important is that the number of wires in it determines the maximum number of memory addresses. For instance, if the address bus could carry only eight bits at a time, the CPU could address only 256 bytes of RAM (28 bytes).D. NETWORK is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of types and categories and also presents the basic components of a network.E. SIGNAL is a codified message, that is, the sequence of states in a communication channel that encodes a message. is any time-varying or spatial-varying quantity.F. LOCAL AREA NETWORK (LAN) - is a computer network covering a small physical area, like a home, office, or small groups of buildings, such as a school, or an airport. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.G. WIDE AREA NETWORK (WAN)- is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries [1]). This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.H. NETWORK SERVERAlmost the entire structure of the Internet is based upon a client–server model. High-level root nameservers, DNS servers, and routers direct the traffic on the internet. is a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet. Network servers typically are configured with additional processing, memory and storage capacity to handle the load of servicing clients.I. WORKSTATION computer workstation is an ergonomically designed area of an office which accommodates a desktop computer and all of its peripherals. Ergonomic design means that the user shouldn't have to assume uncomfortable positions in order to perform his or her duties.<br />5) Briefly describe the different network topologies<br />Ever wonder... how are all of these file, print, fax, and computer resources connected so as to allow the typical desktop computer to access them? Network topology refers to the way networked computers and network resources are connected. The three most widely used topologies are bus, ring, and star. Note that the following network topology diagrams are logical views of the topologies they represent and don’t necessarily match the physical (electrical) interconnections on the networks.Bus NetworkThe bus network topology, connects each computer to a single cable. At each end of the cable is a terminating resistor or a terminator. An electrical signal is passed back and forth along the cable past the computers and between the two terminators. The bus carries a message from one end of the network to the other. As the bus passes each computer, the computer checks the destination address on the message. If the address in the message matches the computer’s address, the computer receives the message. If the address doesn’t match, the bus carries the message to the next computer, and so on.Bus topology is passive, meaning that computers only listen for data being sent on the network and aren’t responsible for moving data from one computer to the next. If one computer fails, it doesn’t affect the entire LAN. On the other hand, if a cable breaks, the entire cable segment (the length between the two terminators) loses its connectivity, so that the entire segment isn’t functional until the cable can be repaired. Each computer attached to a bus network can transmit data whenever it “wants.” This capability means that two computers may try to transmit simultaneously. This occurrence is called a collision. A collision is detected by the network hardware of the sending computers. When a collision is detected, the packets of data that generated the collision are retransmitted.The limitation of bus networks is the speed of data transmission relative to the number of computers on the network. As more computers are added to the network, more collisions are bound to happen. As more collisions occur, more retransmissions take place and the overall network performance degrades.Ethernet is one example of a common bus network found on many local area networks. Ethernet is also the most popular LAN architecture in use today.Ethernet networks can be wired with different types of cable, each with its own benefits and drawbacks. Three popular specifications for Ethernet topologies are 10BASE2, which uses thin coaxial cable (Thinnet) that can carry a signal up to approximately 607 feet; 10BASE5, which uses Thicknet cabling that can carry a signal for about 1,640 feet; and 10BASET, which uses unshielded twisted-pair cable that can carry a message for about 328 feet between a computer and the hub to which the computer is connected.Ring NetworkIn a ring network, a packet of data (often called a token) is continually moving around the ring from one computer to the next. To send data, a computer on the network must wait for the circulating token to pass by. When the token arrives, it’s examined to see whether it’s empty. If it’s empty, the computer that wishes to transmit adds its data to the token packet and addresses the packet to a destination. As the token passes by the destination computer, the computer looks at the address and because the message is addressed to itself, extracts the data, and replaces the token packet’s data with a delivery acknowledgment message. The token then continues to circle the ring and eventually returns to the sending computer. The sending computer examines the token packet to see if it contains the data it sent or an acknowledgment message. If it doesn’t find an acknowledgment message, the sender knows that the data wasn’t received, possibly because the destination computer wasn’t operating.The sender then clears the token packet and passes it along the ring to allow subsequent computers their chance to use the network’s communication resources. The token passing scheme is in contrast to the bus topology whereby any computer can send at any moment and the protocol must detect collisions. Collisions of this nature can’t occur on a ring network.Data on the IBM token-ring network is transmitted at either 4 or 16 Mbps, depending on the actual implementation. For computers to communicate with each other, all network cards must be configured similarly to communicate at either 4 or 16 Mbps on the network. Networked computers are connected by shielded and/or unshielded twistedpair cable to a wiring concentrator called a Media Access Unit or MAU (rhymes with cow). Each MAU can support as many as 72 computers that use unshielded wire or up to 260 computers using shielded wire. Each ring can have as many as 33 MAUs allowing for a theoretical maximum of 8,580 computers on the network.Star NetworkTo transmit data between any two computers in a star network, requires that data be sent via the centrally located computer, called a hub. The hub provides a common connection so that all the computers can communicate with one another. To extend the star network, hubs can be connected to one another. The major problem with star networks is that if the centrally located hub isn’t operating, the entire network becomes unusable. A benefit of a star network is that no computer, other than the centrally located hub, can interrupt network traffic.InternetworkingThe previous section detailed different network topologies. This section will show that these disparate networks can be interconnected and may even be separated by thousands of miles. This scenario is called internetworking. Figure 1.9 shows a well connected network composed of a bus network, a ring network, a satellite connection to a remote server, and a dial-up modem connection. Notice the device called the Gateway. This device is used to connect the bus network to the ring network. Its job isn’t only to bridge the two networks hardware-wise but also to route data between the two when the destination of a data packet isn’t local to either the bus or ring network. In this network, the laptop computer has the same access to resources connected to the bus network’s Workstation computer as does the bus network’s Macintosh computer. Of course the access times may not be the same for the laptop computer and the Macintosh.<br />