Side-port Memory Interface (RS690T Only)
© 2008 Advanced Micro Devices, Inc.
41978 AMD RS690M Databook 3.06
Proprietary
2-3
Figure 2-3 RS690M Host Bus Interface Signals
2.2
Side-port Memory Interface (RS690T Only)
In order to significantly decrease system power and increase graphics performance, the RS690T provides an optional
side-port memory interface for dedicated frame buffer memory, to be used exclusively for the integrated graphics core.
The side-port memory interface can significantly reduce system power by allowing the CPU to stay in its lowest power
state during periods of inactivity. Screen refreshes are fetched from the side-port memory, and there is no need to "wake
up" the CPU to fetch screen refresh data.
The RS690T memory controller is unique and highly optimized. It operates in 16-bit mode at very high speed (up to
DDR2-800), and has a new programmable interleaved mode that significantly increases the memory bandwidth and
reduces data latency to the integrated graphics core. The additional bandwidth provided to the internal graphics core will
also aid the RS690T in reaching and exceeding Microsoft's Windows Vista
TM
Premium logo requirements.
2.2.1 DDR2 Memory Interface
Figure 2-4, “RS690T Side-port Memory Interface,” on page 2-4
, illustrates the side-port memory interface of the
RS690T.
The RS690T memory controller supports up to 128MB of dedicated side-port frame buffer memory. It controls a single
rank of DDR2 devices in 16-bit memory configuration. It supports device sizes of 256, 512, and 1024 Mbit, and device
widths of x8 and x16. Because the memory controller supplies only one chip select signal, only DDR2 devices with one
chip select are supported. A wide range of DDR2 timing parameters, configurations, and loadings are programmable via
the RS690T memory controller configuration registers
HT_RXCADN
2
2
RS690
M
AM
D C
P
U
HT_TXCALP
HT_RXCALN
HT_RXCALP
VDD_HT
HT_TXCALN
HT_RXCADP
HT_RXCTLN
HT_RXCTLP
HT_RXCLKN
HT_RXCLKP
16
16
HT_TXCADN
2
2
HT_TXCADP
HT_TXCTLN
HT_TXCTLP
HT_TXCLKN
HT_TXCLKP
16
16
