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Unit-1, Module- 5 Structural and Functional view of Computer Question 1 : Show the structural and functional view of a computer based on the Von Neumann Stored Programmed Principle. Solution 1 : Von Neumann architecture is also referred to as the IAS computer and was developed at the Princeton Institute for Advanced Studies. The basic structural and functional view of a computer according to Von Neumann stored program architecture is shown in the figure below: The functionalities of the individual blocks are as follows Central Processor Unit (CPU): CPU consists of two basic blocks: o The control unit has a set of registers and it generates control signals for the Arithmetic and Logic Unit (ALU). These signals control flow of data to (from) the input (output) ports of the ALU and initiate the required computation. o The execution unit or data processing unit (i.e. ALU) contains a set of registers for storing data and hardware like adder, multiplier etc. for execution of arithmetic and logical operations.
In addition, CPU may have some additional registers for temporary storage of data. Input Devices: Input devices feed data from outside to the CPU. The data can be program or data which is to be processed. Input data is read into Memory unit from input device or under the control of CPU input instructions. Example of input devices: Keyboard, Mouse, Hard disk, Floppy disk, CD-ROM drive etc. Output Device: With the help of output device computational results of the CPU can be provided to the user. Output data from main storage go to output device under the control of CPU output instructions. Example of output devices: Printer, Monitor, Plotter, Hard Disk, Floppy Disk, CD ROM, Hard disk etc. Memory Unit: Memory unit is used to store the data and program. CPU can work with the information stored in memory unit. Example of memory devices: Hard Disk, Floppy Disk, Magnetic Tape, CD-ROM, Pen drive etc.
The figure below illustrates the expanded structure of a Von Neumann computer with the registers.
Question 3: What is a BUS? How the bus is used to connect different components of a computer. Solution 3: Broadly speaking, Bus is a wire that connects two electrical ports so that signals can be transferred between them. The term Bus has been derived from the Latin word omnibus , meaning "for all". In terms of computer architecture, a bus is a set of electrical connections (cables, connections in printed circuit board or fabricated on-chip etc.) which can be shared by multiple hardware modules in order to communicate with one another. One key difference between the term “wire” and “Bus” is that, more than one parallel wire can be present in a single Bus between the points it connects. In a CPU is the following are the main three Buses Address Bus: Sends the address of the memory location (to be read/written) to the memory from CPU. It is a unidirectional bus. Data Bus: Sends/receives data in between the CPU, Memory and I/O devices. It is a bidirectional bus. For example, if a memory location is to be read then data bus sends the data from the respective memory location (that is given in address bus) to the CPU. Control Bus: The control bus is used to control and co-ordination the data transfers between the hardware modules interconnected by the address and data bus. It is also a bidirectional bus. For example, whether a memory location will be read or written is determined by a control line. The broad architecture showing the interconnections of CPU, memory and I/O devices using the three Buses is shown below.
