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What is the use of the extra segment in a 8086 processor?
extra segment is a 16-bit register containing address of 64KB segment, usually with program data. By default, the processor assumes that the DI register points to the ES segment in string manipulation instructions. ES register can be changed directly using POP and LES instructions. It is possible to change default segments used by general and index registers by prefixing instructions with a CS, SS, DS or ES prefix. any corrections most welcome
How the speed of 8086 microprocessor can be increased?
To increase the speed of the 8086, you need to increase the clock speed, reduce the number of wait states, or both. You could also optimize your code so that it runs faster. Since the 8086 is a segmented memory architecture, it is more efficient to use operands in one segment and to make near references to them.
What is segment address?
A segment address is the contents of a segment register, CS, DS, ES, or SS. It is used after effective address generation to provide an offset in physical memory, by multiplying the segment register by 16 and then adding it to the effective address, giving a 20 bit address. This gives you addressability to 65536 segments of 65536 bytes, each separated by 16 bytes. The register used is usually implicit based on use; CS for code, DS for data, ES for certain string operations, and SS for stack. A segment override prefix can be used to select a different segment register.
Explain about segment registers in 8086MP?
There are four segment registers in the 8086/8088 processor, CS, DS, ES, and SS, also known as Code Segment, Data Segment, Extra Segment, and Stack Segment. Any time an address is generated by the processor, it is added to the value of one of the segment registers, after that segment register is effectively multiplied by 16, or left shifted four bits, in order to generate the physical address that accesses memory. This gives an effective address range of 20 bits, or 1mb, but note that only 64kb is addressable through any segment register at one time, unless you stop to change the contents of that segment register. This is known as a segmented architecture. By default, the CS register is used when fetching instructions, the DS register is used when accessing data, the SS register is used when accessing the stack, and the ES register is used during certain string type instructions. If desired, an instruction prefix can be used to override, such as forcing use of CS instead of DS when using a table contained within opcode space.
How do you use the word override in a sentence?
The judge will override the sentencing she received.
Use the word override in a sentence?
Users can choose to override the default selections.
What is the Override Value for DirectX?
I would have to go with 100 that the override value I use. -tech-
What are segment?
In the x86 processor architecture, memory addresses are specified in two parts called the segment and the offset. One usually thinks of the segment as specifying the beginning of a block of memory allocated by the system and the offset as an index into it. Segment values are stored in the segment registers. There are four or more segment registers: CS contains the segment of the current instruction (IP is the offset), SS contains the stack segment (SP is the offset), DS is the segment used by default for most data operations, ES (and, in more recent processors, FS and GS) is an extra segment register. Most memory operations accept a segment override prefix that allows use of a segment register other than the default one.
What are segment registers?
In the x86 processor architecture, memory addresses are specified in two parts called the segment and the offset. One usually thinks of the segment as specifying the beginning of a block of memory allocated by the system and the offset as an index into it. Segment values are stored in the segment registers. There are four or more segment registers: CS contains the segment of the current instruction (IP is the offset), SS contains the stack segment (SP is the offset), DS is the segment used by default for most data operations, ES (and, in more recent processors, FS and GS) is an extra segment register. Most memory operations accept a segment override prefix that allows use of a segment register other than the default one.
Why you Use Memory Segmentation In 8086 Microprocessor?
The 8086/8088 is a 16 bit processor running on a 16 bit (8086) or 8 bit (8088) bus with a 20 bit address bus. In order to obtain the extra 4 bits of addressibility, Intel designed segment registers that are effectively multiplied by four and then added to the 16 bit offset address generated by the instruction. This yields 64K segments of 64KB each, although they overlap each other at a distance of 16 bytes.
A Explain the use of Code Segment CS and data segment DS register in 8086 microprocessor?
Code segment (CS) is a 16-bit register containing address of 64 KB segment with processor instructions. The processor uses CS segment for all accesses to instructions referenced by instruction pointer (IP) register. CS register cannot be changed directly. The CS register is automatically updated during far jump, far call and far return instructions. Data segment (DS) is a 16-bit register containing address of 64KB segment with program data. By default, the processor assumes that all data referenced by general registers (AX, BX, CX, DX) and index register (SI, DI) is located in the data segment. DS register can be changed directly using POP and LDS instructions. Code segment (CS) is a 16-bit register containing address of 64 KB segment with processor instructions. The processor uses CS segment for all accesses to instructions referenced by instruction pointer (IP) register. CS register cannot be changed directly. The CS register is automatically updated during far jump, far call and far return instructions. Data segment (DS) is a 16-bit register containing address of 64KB segment with program data. By default, the processor assumes that all data referenced by general registers (AX, BX, CX, DX) and index register (SI, DI) is located in the data segment. DS register can be changed directly using POP and LDS instructions.
What is the complete explanation about segment register?
A segment register contains a biased address which is used to calculate the physical address of a memory reference. The physical address calculation is ... APHYSICAL = ASEGMENT * 16 + ALOGICAL ... where the logical address is the effective address generated by the CPU instruction, also called the offset address. There are four segment registers, CS, SS, DS, and ES, standing for Code Segment, Stack Segment, Data Segment, and Extra Segment. Each is 16 bits in size, and is selected either in context of the particular operation or by use of a segment override prefix instruction. Normally, CS is used for code, SS is used for stack operations (including BP relative calculations), DS is used for data, and ES is used as the second operand in certain repeated string operations. Since the segment register is 16 bits in size, and the offset (logical) address is also 16 bits in size, the effective range of the physical address is 20 bits, or one megabyte. This is due to the segment address being multiplied by 16, i.e. left shifted by 4. This is called a segmented architecture, and allows for single instruction access to 64 KB of data at any one time. With two instructions, however, you can get to any of 1MB of data. Note that this is not the same as virtual addressing. The 8086/8088 does not provide virtual (or protected) addressing.
