X86 Computer Bus Subsystems IBM PC/XT Architecture ('82, '83)
X86 Computer Bus Subsystems IBM PC/XT Architecture ('82, '83)
X86 Computer Bus Subsystems IBM PC/XT Architecture ('82, '83)
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EISA<br />
ISA ISA EISA<br />
EISA Pinout<br />
Local <strong>Bus</strong>ses – VLB, <strong>PC</strong>I, AGP<br />
• EISA BW Still Too Slow For Video<br />
• Need Direct Access to x86 System <strong>Bus</strong><br />
– for VRAM write/read<br />
• VESA Developed VLB (1992)<br />
– designed to operate “with” ISA or EISA or MCA<br />
– use IRQ and DMA support of Adapter <strong>Bus</strong><br />
– VLB portion operates at system bus speed (50 or 66 MHz)<br />
– no automatic configuration support<br />
– x86 only bus<br />
• <strong>PC</strong>I<br />
– developed with ISA Compatibility in mind<br />
– New <strong>Bus</strong> – Extension in the Sense of Compatibility<br />
– Requires a “Bridge” Circuit<br />
• AGP<br />
– Advanced Graphics Port<br />
– Extension to <strong>PC</strong>I Standard 66MHz<br />
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