RM7965A-900UI 900 MHz 64-bit Microprocessor Data Sheet
6
System Interface
The RM7965A product provides a high performance system interface comprised of a
multiplexed address/data bus (SysAD), a parity check bus (SysADC) and a system command
bus (SysCmd). The SysAD is 64-bits, SysADC is 8-bits, and SysCmd is 9-bits.
Figure 7 shows a typical embedded system using the RM7965A. The diagram shows a system
with a bank of DRAMs, and an external agent or ASIC which provides DRAM control and I/O
functionality.
Figure 7 Typical Embedded System Block Diagram with 64-bit SysAD Bus
Address
Flash/
Boot
ROM
DRAM
Control
x
x
8
64
SysAD + SysADC
External
Agent
RM7965A
72
PCI Bus
SysCmd + Control
25 (typ)
There are many companion chips or system controllers that interface to the SysAD bus that
provide connectivity to a variety of interfaces including PCI, PCI-X, Fast Ethernet, Gigabit
Ethernet, and T1/T3. They typically include a boot bus that connects to flash or ROM memory,
which can be utilized to boot any RM7965A CPU across the SysAD bus.
6.1 System Address/Data Bus
RM7965A product features an enhanced version of the multiplexed Address/Data bus (SysAD),
first introduced with the debut of the RM70xxC products. The function of the SysAD bus is to
transfer addresses and data between the CPU and the rest of the system. The enhanced version
can run up to 200 MHz, providing up to 12.8 Gbit/s or 1.6 GB/s of bandwidth. It supports
legacy designs with a seamless upgrade path for all RM70xx and RM52xx processors, and
maintains compatibility with all existing and future companion chips that utilize SysAD
functionality.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2100294, Issue 2
38
PMC [ PMC-SIERRA, INC ]
