AcceleRAM LowFB Technology

S3 Graphics AcceleRAM LowFB (Low Frame Buffer) Technology is a combination of hardware and software that enables this new and unique architecture. In this configuration, a part of the larger system main memory (DDR2 DIMMs), called PCIe memory, is used as part of the overall video memory, which includes a small amount of dedicated local video memory.

The consumer benefits, as this unique technology now allows entry level end users the capability of getting all the rich features found in a discrete graphics processor at a low cost while maintaining or surpassing the performance level of competitive solutions in this market segment.

Note: Size and width of the small Local Video Memory can be 64MB/32bit (3.2 GB/s) to 128MB/64bit (6.4 GB/s) @ 400 MHz DDR2. It can also be 64MB/64bit (8.0 GB/s) to 128MB/28 bit (16.0 GB/s) @ 500 MHz DDR3. This is all dependent upon performance requirements. For systems prior to June 1, 2007, Microsoft Windows Vista will require 512MB of system main memory (DIMMs). Therefore, to get the Premium logo, systems will probably ship with 1.0 GB of system main memory. For systems after June 1, 2007, Windows Vista will require 1.0 GB of system main memory. Therefore, to get the Premium logo, systems will probably ship with 1.5 GB of system main memory. Anything above the memory requirements for Windows Vista, would be used as the Dynamic PCIe System Frame Buffer Memory as well as other system main memory requirements. This large system main memory requirement dramatically increases the overall system cost and necessitates the need for a great low frame buffer technology GPU. The DDR2 @ 400 MHz (3.2 GB/s) local video memory is for a typical case in the low frame buffer market segment. The 128bit @ 333 MHz (10.672 GB/s) system main memory is for a typical case in the mainstream market segment.

With the introduction of Microsoft® Windows® VistaTM operating system, the system main memory (DIMM) requirement has increased. For systems prior to June 1, 2007, Windows Vista will require, 512MB of system main memory, which means that most, if not all, systems that want to have the Premium logo, will probably ship with 1.0GB of system main memory. After June 1, 2007, Windows Vista will require, 1.0GB of system main memory, which would mean that most, if not all, systems that want to have the Premium logo, will probably ship with 1.5GB of system main memory. This is the current Microsoft Windows Vista requirement. This would dramatically increase the overall system cost and necessitate the need for a GPU with great low-frame buffer technology.

FBManager Operation

In an AcceleRAM LowFB configuration, the amount of PCIe memory available from the larger system main memory impacts the performance of the graphics subsystem and the demand of the PCIe memory actually fluctuates from time to time depending upon the mode, application, and type of data required. The FBManager will intelligently and dynamically determine how much PCIe memory is required, beyond the Windows Vista requirement, for optimum graphics performance.

The FBManager also intelligently and efficiently manages the transfer of data from PCIe memory to the GPU for immediate and direct operation and/or to the small dedicated local video memory for future operation to achieve optimum performance. The GPU does not have to wait for data to be transferred from PCIe memory into its small dedicated local video memory to be able to operate on it, which would decrease performance. It can operate directly on some of the data as it is being transferred from PCIe memory by the FBManager. The FBManager dynamically determines the appropriate size of the PCIe memory, what type of data is stored there, as well as what type of data is stored in the small dedicated local video memory, and what type of data is required by the GPU for a given 3D application to obtain the optimum performance. Once the 3D application is closed, the FBManager frees up the PCIe memory which is now made available to the system again.

Conclusion

With AcceleRAM LowFB Technology, S3 Graphics GPUs can easily meet the Windows Vista Premium logo memory bandwidth requirement of 1.6GB/s. It will also achieve a minimum WEI rating of 3, in a mainstream configuration.

It also provides a great balance of performance, features, and cost for the entry level market segment. Implementing AcceleRAM LowFB allows system vendors to provide a perfect middle ground between the low performance, minimum features, and low cost UMA graphics and the high cost discrete graphics solutions that are currently available in the market.

Check out our AcceleRam White Paper.