User`s guide

3.3 21071-DA Functional Overview
The 21071-DA is a bridge between the PCI local bus and the 21064A
microprocessor and its L2 cache and memory. The 21071-DA contains all
control functions of the bridge and some data path functions. Other data path
functions reside in the 21071-BA.
The 21071-DA can be divided into two major sections: the sysBus (processor,
memory) interface and the PCI interface. The following sections describe the
sysBus and PCI interface features. Figure 3–6 shows a block diagram of the
21071-DA.
Figure 3–6 DECchip 21071-DA Block Diagram
LJ03949A.AI
4-Entry
DMA Write
Address
FIFO
DMA Read Address
DMA Write
Address
ad<31:0>
Read
Bypass
MUX
3 LW DMA
Read I/O
Write Buffer
epiData<31:0>
8-Entry
TLB
PCI Window
Hit Detection
Parity Check
Generation
cbe<3:0>
par
epiErr<31:0>
CSRs and
Error Logging
Address
MUX and
Merge Logic
DMA Write
I/O Read Data
DMA Read
I/O Write Data
I/O
Address
adr<33:5>
Functional Description 3–13