Specifications

EISA and ISA Bus Support
14.7 EISA Bus Support on DEC 2000
Figure 14–2 EISA Memory Address Space
EISA memory address space as seen by EISA adapter on DEC 2000
ZK−6740A−GE
DEC 2000 System Memory
0000 0000
0FFF FFFF
0000 0000
0FFF FFFF
FFFF FFFF
0010 0000
EISA A<31:0>
1000 0000
0010 0000
1 MB
not
for DMA
available
1 MB
not
accessible
from EISA
bus
E/ISA devices
with memory
buffers are
mapped in 1st MB
EISA
memory
>1 MB
mapped
directly
to system
memory
Host
memory
accessible
from
EISA
256−1 MB
Figure 14–3 shows an example of installing a DE422 EISA Ethernet card in a
DEC 2000/EISA slot 1. The DE422 uses slot specific I/O space for control register
access and requires a 64KB EISA memory buffer. For this example, assume
the DE422 is in slot 1, and the ECU has assigned it a buffer address of C0000.
Install a DE422 EISA Ethernet card in a DEC 2000/EISA slot. Figure 14–3
shows a DEC 2000 address map as seen by the CPU.
14–10