1-8
AlphaServer DS20
Service Manual
1.4
System Architecture
An Alpha microprocessor chip is used in this system. The CPU, memory, and the
I/O modules are physically connected to the system board and logically connected
through a switch-based interconnect implemented in a cross-bar switch chipset.
Figure 1-4 Block Diagram
C chip
CPU 1
(optional)
CPU 0
B cache
B cache
8 D chips
P chip
P chip
1 or 2
Memory
Banks
Up to 2
Memory
Banks
64 bit PCI
64 bit PCI
Command, Address, and Control lines for each Memory Array
Control lines for D chips
Memory
Data
Bus
CPU
Data
Bus
CAPbus
PAD
Bus
CMD/
Addr.
CMD/
Addr.
Probe/
Addr.
Probe/
Addr.
PKW1400-98
