
Appendix B: Programming Interface
Memory Map
Range | CPU address | Region | Cached |
0 to 640K | DRAM | yes | |
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640K to 768K | VGA memory | no | |
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768K to 816K | Shadowed VGA BIOS | yes | |
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816K to 896K | Unused — Available for ISA bus | BIOS Setup | |
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896K to 1M | Shadowed System ROM BIOS | yes | |
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1M to 8M | DRAM | yes | |
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| If no DRAM, ISA memory | no |
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8M to 16M | DRAM | yes | |
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| If no DRAM, ISA memory | no |
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16M to 32M | DRAM | yes | |
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| If no DRAM, ISA memory | no |
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32M to 64M | DRAM | yes | |
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| If no DRAM, ISA memory | no |
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64M to | PCI bus/ISA bus alias | no | |
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Top | System ROM BIOS | no | |
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Top 16K | Boot Block ROM BIOS | no | |
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Assigned and Available IRQs
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| Com2 | Com1 |
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| Real |
| IDE |
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| Keyboard | Cascade | or | or |
| Touch | Sound | Floppy | Time | Numeric | Hard |
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| Timer Controller | Interrupt | Com4 | Com3 | LPT | Screen | Blaster | Disk | Clock | Coprocessor | Disk | PCMCIA | Available | |
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IRQ0 | D |
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IRQ1 |
| D |
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IRQ2 |
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| D |
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IRQ3 |
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| D | X | X |
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| X |
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IRQ4 |
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| X | D | X |
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| X |
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IRQ5 |
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| X | X | D | X | X |
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| X |
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IRQ6 |
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| D |
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IRQ7 |
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| X | X | X | X | X |
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| X | X |
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IRQ8 |
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| D |
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IRQ9 |
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| X | X | X | X | D |
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| X |
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IRQ10 |
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| D |
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| X |
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IRQ11 |
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| X | X | X | X | X |
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| X | X |
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IRQ12 |
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| N O T A V A I L A B L E |
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IRQ13 |
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| D |
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IRQ14 |
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| D | X |
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IRQ15 |
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| X |
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| X | X |
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D indicates factory default, X indicates optional or available IRQs
34Planar Clean Screen PC User’s Manual