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1.2
SYSTEM
PCB
System PCB is composed of the following devices:
o
Central processor: CPU (80C86-2) (9.54 MHz/4.77 MHz)
o
Numeric data processor: NPU (8087, optional)
o
Memory
System memory
Expanded memory
BIOS ROM
Video RAM
640 kbytes
384 kbytes
32 kbytes
16 kbytes
o
System support elements
Direct memory access: DMA (82C37)
Timer : (82C53)
Programmable interrupt controller: PIC (82C59)
o
Floppy disk controller: FDC (8565)
o
Keyboard controller: KBC (80C49)
o
Acynchronous communication element: ACE (8570)
o
Gate array
Bus driver
Bus controller
EXP-MEM controller
Display controller
1-3
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