19-02-2013, 10:25 AM
PC IBM Organization
[attachment=51282]
16-Bit Intel Processor Architecture
A-16 bit microprocessor can operate on 16 bits of data at a time.
8086/8088 have the simplest structure
8086/8088 have the same instruction set, it forms the basic set of instructions for other Intel families.
Registers
Data registers: 4 general data registers hold data for an operation.
Address registers: (segment, pointer and index registers) hold the address of an instruction or data.
Status register: FLAG register keeps the current states of the processor.
General Data Register: Used for general data manipulation.
They are 16-bit registers that can also be used as two 8 bit registers: low and high bytes can be accessed separately → more registers to use when dealing with byte-size data.
In addition to being general-purpose registers, they perform special functions:
Memory Segment
Is a block of 2 (64) K Bytes consecutive memory bytes.
Each segment is identified by a 16-bit number called segment number, starting with 0000 up to FFh . Segment registers hold segment number.
Within a segment, a memory location is specified by giving an offset (16-bit) = It is the number of bytes from the beginning of the segment (0→ FFh).
Very popular O.S. for IBM PC is DOS.
DOS manage only 1 M byte memory, does not support multitasking.
DOS is a collection of routines that coordinates the operations of the computer. The routine that executes user command is COMMAND.COM.
Information stored on disk is organized into files. A file has a name and an optional extension.
The BIOS routines are used to perform I/O operations.
DOS routines operate over the entire PC family.
BIOS routines are machine specific.
Each PC model has its own H/W configuration and its own BIOS routines.
The compatibility of PC clones with the IBM PC depends on how well their BIOS routines match those of the IBM PC
The addresses of BIOS routines (interrupt vectors) are placed in memory starting at 00000h.
[attachment=51282]
16-Bit Intel Processor Architecture
A-16 bit microprocessor can operate on 16 bits of data at a time.
8086/8088 have the simplest structure
8086/8088 have the same instruction set, it forms the basic set of instructions for other Intel families.
Registers
Data registers: 4 general data registers hold data for an operation.
Address registers: (segment, pointer and index registers) hold the address of an instruction or data.
Status register: FLAG register keeps the current states of the processor.
General Data Register: Used for general data manipulation.
They are 16-bit registers that can also be used as two 8 bit registers: low and high bytes can be accessed separately → more registers to use when dealing with byte-size data.
In addition to being general-purpose registers, they perform special functions:
Memory Segment
Is a block of 2 (64) K Bytes consecutive memory bytes.
Each segment is identified by a 16-bit number called segment number, starting with 0000 up to FFh . Segment registers hold segment number.
Within a segment, a memory location is specified by giving an offset (16-bit) = It is the number of bytes from the beginning of the segment (0→ FFh).
Very popular O.S. for IBM PC is DOS.
DOS manage only 1 M byte memory, does not support multitasking.
DOS is a collection of routines that coordinates the operations of the computer. The routine that executes user command is COMMAND.COM.
Information stored on disk is organized into files. A file has a name and an optional extension.
The BIOS routines are used to perform I/O operations.
DOS routines operate over the entire PC family.
BIOS routines are machine specific.
Each PC model has its own H/W configuration and its own BIOS routines.
The compatibility of PC clones with the IBM PC depends on how well their BIOS routines match those of the IBM PC
The addresses of BIOS routines (interrupt vectors) are placed in memory starting at 00000h.