IBM NetVista A21 User Manual

Also see for 2254: Hardware Maintenance Manual Hardware Maintenance Manual

Contents

Appendix C. System address mapsThe following charts represent how the hard disk stores different types ofinformation. Address ranges and byte sizes are approximate.System memory mapThe first 640 KB of system board RAM is mapped starting at address hex00000000. A 256-byte area and a 1 KB area of this RAM are reserved for BIOSdata. Memory can be mapped differently if POST detects an error.Table 1. System memory mapAddress range(decimal)Address range (hex) Size Description0 K – 512 KB 00000 – 7FFFF 512 KB Conventional512 K – 639 KB 80000 – 9FBFF 127 KB Extended conventional639 K – 640 KB 9FC00 – 9FFFF 1 KB Extended BIOS data640 K – 767 KB A0000 – BFFFF 128 KB Dynamic video memory display cache768 K – 800 KB C0000 – C7FFF 32 KB Video ROM BIOS (shadowed)800 K – 896 KB C8000 – DFFFF 96 KB PCI space, available to adapter ROMs896 K – 1 MB E0000 – FFFFF 128 KB System ROM BIOS (main memory shadowed)1 MB – 16 MB 1000000 – FFFFFF 15 MB PCI space16 MB – 4096 MB 10000000 – FFDFFFFF 4080 MB PCI space (positive decode)FFFE0000 – FFFFFFFF 128 KB System ROM BIOSI/O address mapThe following table lists resource assignments for the I/O address map. Anyaddresses that are not shown are reserved.Table 2. I/O address mapAddress range (hex) Size (bytes) Description0000 – 000F 16 DMA 10010 – 001F 16 General I/O locations, available to PCI bus0020 – 0021 2 Interrupt controller 10022 – 003F 30 General I/O locations, available to PCI bus0040 – 0043 4 Counter/timer 10044 – 00FF 28 General I/O locations, available to PCI bus0060 1 Keyboard controller byte, reset IRQ0061 1 System port B0064 1 Keyboard controller, CMD/ATAT byte0070, bit 7 1 bit Enable NMI0070, bits 6:0 6 bits Real-time clock, address0071 1 Real-time clock, data0072 1 bit Enable NMI© Copyright IBM Corp. 2001 63