eee410_lecture4 - EEE 410 Microprocessors I Fall 04/05...

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EEE 410 – Microprocessors I Fall 04/05 – Lecture Notes # 4 Outline of the Lecture Memory Map of the IBM PC Pushing and Popping Operations (Stack) Flag Registers and bit fields M EMORY M AP OF THE IBM PC ¾ The 20-bit address of the 8086/8088 allows 1M byte of (1024 K bytes) memory space with the address range 00000-FFFFF. ¾ The allocation of the memory is called a memory map . RAM : Memory locations from 00000H to 9FFFFH (640K) are set aside for RAM. In an IBM PC the DOS operating system first allocates the available RAM on the PC for its own use and let the rest be used for applications such as word processors. The amount of memory used by DOS varies among its various versions. That is why we do not assign any values for the CS, DS, SS, and ES. Memory management functions within DOS handle this for the operating system. Video RAM : Memory locations from A0000H to BFFFFH (128K) are set aside for video. This amount varies depending on the video board installed on the PC. ROM: Memory locations from C0000H to FFFFFH (256K) are set aside for ROM. First 64 K bytes is used by BIOS (Basic Input/Output System) ROM. Some of the remaining space is used for adapter cards. Function of BIOS ROM: CPU can only execute programs that are stored in memory, there must be some permanent
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This note was uploaded on 05/26/2011 for the course EEE 410 taught by Professor Hasandemirel during the Spring '10 term at Eastern Mediterranean University.

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eee410_lecture4 - EEE 410 Microprocessors I Fall 04/05...

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