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Computer Architecture Articles
Page 11 of 26
What are Program Control Instructions?
Instructions of the computer are always stored in consecutive memory locations. These instructions are fetched from successive memory locations for processing and executing.When an instruction is fetched from the memory, the program counter is incremented by 1 so that it points to the address of the next consecutive instruction in the memory. Once a data transfer and data manipulation instruction are executed, the program control along with the program counter, which holds the address of the next instruction to be fetched, is returned to the fetch cycle.Data transfer and manipulation instructions specify the conditions for data processing operations, whereas the ...
Read MoreWhat is data transfer instruction process in Computer Architecture?
Data transfer instructions transfer the data between memory and processor registers, processor registers, and I/O devices, and from one processor register to another. There are eight commonly used data transfer instructions. Each instruction is represented by a mnemonic symbol.The table shows the eight data transfer instructions and their respective mnemonic symbols.Data Transfer InstructionsNameMnemonic SymbolsLoadLDStoreSTMoveMOVExchangeXCHInputInOutputOUTPushPUSHPopPOPThe instructions can be described as follows −Load − The load instruction is used to transfer data from the memory to a processor register, which is usually an accumulator.Store − The store instruction transfers data from processor registers to memory.Move − The move instruction transfers data from ...
Read MoreWhat are the types of Instructions in Computer Architecture?
Instructions in a computer can be of multiple lengths with a variable number of addresses. The various address fields in the instruction format of a computer vary as per the organization of its registers. It depends on the multiple address fields the instruction can be categorized as three address instructions, two address instructions, one address instruction, and zero address instruction.Three Address InstructionsThe general format of a three address instruction is defined as −operation source 1, source 2, destinationADD A, B, Cwhere A, B, and C are the three variables that are authorized to a different area in the memory. ‘ADD’ ...
Read MoreWhat is Memory Stack in Computer Architecture?
A stack can be executed in the CPU by analyzing an area of the computer memory to a stack operation and utilizing a processor register as a stack pointer. In this method, it is performed in a random access memory connected to the CPU.An area of the computer memory is broken into three segments such as program, data, and stack. The address of the next instruction in the program is saved in the pointer Program Counter (PC). The Address Register (AR) points to an array of the information. SP continually influences the address of the element present at the top ...
Read MoreWhat are Symbolic Microinstructions?
The microinstructions can be determined by symbols. It is interpreted to its binary format with an assembler. The symbols should be represented for each field in the microinstruction. The users should be enabled to represent their symbolic addresses. Each line in an assembly language represents symbolic instruction. These instructions are divided into five fields such as label, micro-operations, CD, BR, and AD.The fields that specify the following information are as follows −The label field may be empty or it may specify a symbolic address. A label is terminated with a colon (:).The micro-operations field consists of one, two, or three ...
Read MoreWhat is the Format of Microinstruction in Computer Architecture?
A microinstruction format includes 20 bits in total. They are divided into four elements as displayed in the figure.F1, F2, F3 are the micro-operation fields. They determine micro-operations for the computer.CD is the condition for branching. They choose the status bit conditions.BR is the branch field. It determines the type of branch.AD is the address field. It includes the address field whose length is 7 bits.The micro-operations are divided into three fields of three bits each. These three bits can define seven different micro-operations. In total there are 21 operations as displayed in the table.Symbols with their Binary Code for ...
Read MoreWhat is Microprogram Sequencing?
The microcode for the control memory should be generated by the inventor once the configuration of the computer is settled. The generation of code is known as microprogramming.There are various points to be treated while designing the microprogram sequencer are −Size of the microinstructionTime of address generationThe microinstruction’s size should be in the least, therefore that the control memory necessary is less and the cost is decreased. Microinstructions can be implemented at a quicker rate if the time to create an address is less. This results in raised throughput.Disadvantage of Micro-program SequencingThe disadvantage of microprogram sequencing is as follows −If ...
Read MoreWhat are Subroutines?
Subroutines are programs that are used by other routines to accomplish a particular task. A subroutine can be called from any point within the main body of the micro-program. Frequently, many micro-programs contain identical sections of code. Microinstructions can be saved by employing subroutines that use common sections of microcode.For example, the sequence of micro-operations needed to generate the effective address of the operand for instruction is common to all memory reference instructions. This sequence could be a subroutine that is called from within many other routines to execute the effective address computation.Micro-programs that use subroutines must have a provision ...
Read MoreWhat is Instruction Mapping in Computer Architecture?
A unique type of branch exists when a microinstruction defines a branch to the first word in control memory where a micro-program routine for instruction is placed. The status bits for this type of branch are the bits in the operation code part of the instruction. For example, a computer with a simple instruction format as shown in the figure.It has an operation code of four bits which can specify up to 16 distinct instructions. It can consider that the control memory has 128 words, needing an address of seven bits. For each operation code, there exists a micro-program routine ...
Read MoreWhat is Conditional Branching?
A conditional branch instruction is a branch instruction that may or may not generate a transmission of control that relies upon the value of stored bits in the PSR (processor status register). It provides decision-making capabilities in the control unit.The status conditions are special bits in the system that provide parameter information such as the carry-out of an adder, the sign bit of a number, the mode bits of instruction, and input or output status conditions. Information in these bits can be tested and actions initiated based on their condition: whether their value is 1 or 0.The status bits, together ...
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