Digital Equipment CELEBRIS 5100, Service Maintenance Manual, Page: 77 / 94

Digital CELEBRIS Pentium PC Device Mapping
MCS Logistics Engineering - Nijmegen 77
Chapter 5 Device Mapping
This section provides a series of tables listing mapping and address information related to computer
memory and various main logic board devices (keyboard controller, interrupt controller, DMA controller,
etc.).
The computer’s memory and address locations are allocated at the factory to operate within a standard PC
environment. However, due to the number of optional devices and/or expansion boards that are available,
sometimes memory and address locations need to be changed. For example, some network expansion
boards require a specific memory location. If that location is already allocated, a memory conflict results
and the expansion board will not operate as expected. Note that some memory, I/O and interrupt locations
can be changed using the BIOS Setup utility.
CAUTION
Before changing any memory or address location, refer to the documentation supplied
with the optional device, expansion board, or software application and make sure
adequate information is available.
CPU Memory Address Map (Full Range)
Range Function Notes
0 KB to 640 KB Main memory PC compatibility range
640 KB to 1024 KB
Main memory PC compatibility range (ISA memory lower limit)
1 MB to 16 MB Main memory
Memory space gap ISA memory upper limit
16 MB to 128 MB Main memory Computer memory upper limit
64 MB to 4 GB
PCI memory Only Venturis 560 Series
128 MB to 4 GB PCI memory Only Venturis FP400 Series
CPU I/O Address Map
Range (hexadecimal) Function
0CF8 to 0CFF PCI configuration space enable registers
1000 to FFFF
PCI I/O space