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
test is used by 8086 to check whether 8087(co-processor) is ready or busy..
Memory segmentation in the 8086/8088 is used to allow the processor to access more than 64kb of memory, even though it is only a 16-bit processor. Each segment register allows access to one of 64k 64kb segments, each overlapping by 16 bytes, with the total addressibility being 1mb.
Because that's the way Intel designed it. A segment register is 16 bits. That is 65536, or 64K, different values. Also, the processor is a 16 bit processor, and offset values can only contain 65536, or 64K, different values.
In the 8086 microprocessor, the Code Segment (CS) register contains the paragraph address that will be added to the Instruction Pointer to obtain the address of the next instruction. Similarly, the Data Segment (DS) register contains the paragraph address that will be added to the Effective Address that is computed to find the address of the data used by that instruction. There are segment override prefixes, but the default use is CS for instructions and DS for data.'normal' address space in 8086 is 16 bit r which allows it to address 64k of linear memory space. Using segment registers to select a 'bank of memory' the CPU can use much more (20 bit addressing space)
Real mode processor works as 8086/8088 while Protected mode processsor works as 80286
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.
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.
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.
better read books~!
Because IBM wanted to build a computer with an 8-bit data bus. The 8086 and 8088 are the same processor, with the 8086 running on a 16-bit data bus, and the 8088 running on an 8-bit data bus. This allowed IBM to make the most use of older designs that supported 8-bit data buses, such as the 8080, the 8085, and the Z80.
There were about 20,000 active transistors in the 8086.
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.
Manual coding of 8086 is difficult hence we use a assembler or a compiler. Note that the microprocessor should be able to interpret your discussions via the program. Suppose if the instruction corresponds to word(16 bits), we use assembler directive WORD PTR, but when assembler is contacting the processor it sets a bit called 'w' indicating its a byte operation.
The 8088 is an 8 bit bus implementation of an 8086, which is a 16 bit processor. The reason for providing the 8088 variant is simply to minimize the hardware cost and complexity of designing a system to use the 8088. This is the approach used for the first IBM PC. Some implementations, such as the Tandy 1000SX, used the 80186, a highly integrated version of the 8086, in a 16 bit bus configuration. Later versions, in order to increase performance, went ahead and provided 32, 64 and 128 bit bus implementations of advanced processors.And, no, the 8086 is not a multiprocessing computer. It is a single processor. Intel did not get into multiprocessing until the Xeon and the Pentium IV.
The 8086/8088 does not have memory management, at least in the style of virtual memory, like its successors.
You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.You could use a word processor or a desktop publisher.
The 12v 8-pin conector is used for extra power for the processor.
It all depends on the flow of the instruction stream. If the processor fetches the memory location under direct fetch under control of the program counter, it is clearly an instruction. If the processor accesses the memory location as a result of fetching or storing an operand, it is clearly data. Where it may be unclear, and subject to interpretation, is when the fetch is part of a table lookup indexing through an array. It could go either way, depending on how you look at it. In the 8085, if S0 and S1 are both high during a fetch, it is an opcode fetch. The 8086/8088 is similar but S0 and S1 are inverted in that case, i.e. both low during opcode fetch. The bottom line is that, for the 8085, it does not matter because there is only one address space and, for the 8086/8088, the processor knows when to use CS (Code Segment) versus DS (Data Segment).
The 8087 Numeric Data Processor is an adjunct to the 8086/8088 microprocessor, that gives the 8086/8088 floating point capability and 8 more registers. The 8087 integrates itself with the 8086/8088 in such a way that the pair actually becomes one processor, appearing to have the extra instructions and registers to start with.Since it was an optional add-on to the system, many run-time libraries would detect whether or not the 8087 was present, and either use it or emulate it.This separation of functionality into two chips was maintained in the product line up until the 80386DX and 80486, although the NDP was called something else (such as the 80287, and 80387) at which point the NDP became a permanent part of the instruction set.
Segmentation is a Memory Management technique in which memory is divided into variable sized chunks which can be allocated to processes. Each chunk is called a segment. A table stores the information about all such segments and is called Global Descriptor Table (GDT). A GDT entry is called Global Descriptor. It comprise of :To translate a logical address into a linear address, the processor does the following: # Uses the offset in the segment selector to locate the segment descriptor for the segment in the GDT or LDT and reads it into the processor. (This step is needed only when a new segment selector is loaded into a segment register.) # Examines the segment descriptor to check the access rights and range of the segment to insure that the segment is accessible and that the offset is within the limits of the segment. # Adds the base address of the segment from the segment descriptor to the offset to form a linear address. If paging is not used, the processor maps the linear address directly to a physical address (that is, the linear address goes out on the processor's address bus). If the linear address space is paged, a second level of address translation is used to translate the linear address into a physical address.A segment selector is a 16-bit identifier for a segment. It does not point directly to the segment, but instead points to the segment descriptor that defines the segment. A segment selector contains the following items: ; Index ; : (Bits 3 through 15). Selects one of 8192 descriptors in the GDT or LDT. The processor multiplies the index value by 8 (the number of bytes in a segment descriptor) and adds the result to the base address of the GDT or LDT (from the GDTR or LDTR register, respectively). ; ;TI (table indicator) flag ; : (Bit 2). Specifies the descriptor table to use: clearing this flag selects the GDT; setting this flag selects the current LDT. ;
Check your motherboard or call your manufacturer. Make extra sure before you buy a processor, as many will be incompatible.
The Source Index (SI) register is used by certain string type instructions to read from memory. Typically, the instruction is "repeated" with a repeat prefix to iterate through memory until some condition is met.
Maybe you mean the prefetch queue?
The graphics processor should already be in use if your driver is installed. if the driver is not installed then you can download and install it from the respective processor brand.