Memory Organization Computer Organization and Architecture by admin - January 4, 20230 Memory Organization Every computer system has following types of memory devices. The different types of memory can be explained as the memory hierarchy. Memory Hierarchy: The total capacity of the memory in a system can be visualized as a hierarchy of memory devices. It includes all memory devices employed in a computer from large size but very slow-speed to small size but very-high speed devices. The memory hierarchy can be represented as shown in figure below. IOP is used to communication between main memory and the auxiliary memory. Cache is used to communicate between CPU and the main memory. Internal or the primary memory: The internal memory consists of random access memory (RAM), read only memory (ROM) and some high-speed memory such as cache memory.
Modes of IO Transfer Computer Organization and Architecture by admin - January 4, 20230 Modes of Transfer: The data transfer between the CPU and the i/o device is through the memory. Data transfer between the CPU and I/O may be handled in a variety of modes. These are: Programmed I/O Interrupt I/O Direct Memory Access(DMA) Programmed I/O Mode : This mode uses the CPU as an intermediate path for the data transfer. Each data item is initiated by an instruction. Data transfer under this mode requires constant monitoring of the peripheral by checking the status flag which indicate whether the device is ready to receive or send the data. In this method the CPU stays in a program loop until the i/o unit is ready for data transfer. This method is quite slow. Interrupt I/O In this method instead
Assembler Computer Organization and Architecture by admin - December 29, 2022January 1, 20230 Introduction Computer instructions are referenced from Instruction Types here for the purpose of reference. These are used by the assembler while translating the symbolic code to its binary code. Instructions were categorized as MRI Instructions : Direct or indirect memory reference instructions Non-MRI instructions: Instructions does not make a reference to memory, These are register reference or the I/O reference type of instructions. Category or Type of Programming languages Computer or specifically the processor understands and can execute the binary language programs only. Programs written in any other language must be translated to the machine or binary language. The programs may be developed using one of the following types of programming languages: Binary or machine level language: This is the computer natural programming language that
Addressing Modes Computer Organization and Architecture by admin - December 21, 2022December 21, 20220 Addressing Modes The instruction format for a general purpose computer was described in Instruction Types states that the OP-Code field specifies the operation to be performed, data is required to be supplied to ALU for this operation. Addressing Mode The way the data or the operands are chosen during the execution of a program depends on how the data is to be supplied since data may come from input devices, from memory or from registers etc. So, the addressing mode specifies the rule or the methods for interpreting the address fields of the instruction before the operand is actually referred. Purpose of the addressing modes: To give programming versatilities to the user by providing different ways of addressing or referencing to data such as naming variables,
Design of ALU Digital Logic and Computer Design by admin - December 15, 2022December 15, 20220 Design of ALU ALU forms one of the important block of a digital computer. It is a multi-operation, combinational circuit. Number of operations supported depend on the complexity of its design. It takes two numbers of n-bit wide as input, performs an operation depending on the function select inputs and produces the output Fn, It also has carry-in input to provide additional functionality and carry-out line which can be part of the result or can act as input to the next stage when the functionality is extended to accommodate numbers with more number of bits. If an ALU has k function select lines, then it will have 2k operations. Figure-1 shows the block diagram of an ALU. Modular design technique can be