Memory Hardware Considerations
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8/27/2008
For information about how software uses random access memory (RAM), read-only memory (ROM), and mass storage, see RAM, ROM, and Mass Storage Comparison. For information about developing device drivers for a specific type of device, see Windows CE Drivers.
SDRAM
To run software on a networked media device (NMD), your hardware must have 32-bit wide synchronous dynamic random access memory (SDRAM), with a minimum frequency of 100 megahertz (MHz). To provide a better user experience with smoother audio and video playback, use more SDRAM to buffer more audio data and video data. Additionally, an NMD that has more SDRAM can run more applications in parallel on the target device.
The following table shows the required and recommended amounts of SDRAM for an NMD and for a digital video recorder (DVR).
| SDRAM requirement level | NMD | DVR |
|---|---|---|
Required |
32 megabytes (MB) |
32 MB |
Recommended |
64 MB |
128 MB |
ROM or Flash Memory
ROM or flash memory stores the operating system (OS) and the application software. The bit width of your ROM or flash memory must be either 16 or 32. You can use NAND-based or NOR-based flash memory. You can use other media, such as a hard disk drive, to store the run-time image. Keep in mind that due to moving parts, hard disk drives are less reliable than solid-state media.
You must reserve 2 MB of ROM or flash memory in order for the boot loader to operate. In the boot loader, you must implement a master reset method for all ROM or flash memory, which includes the file system and the registry.
To support execute-in-place (XIP) functionality, you must use the appropriate type of ROM or flash memory. If you do not take advantage of XIP, then before the boot loader runs software, the boot loader and the operating system must copy software from ROM or from flash memory to RAM.
Using more ROM or more flash memory permits more features and applications to reside on the networked media device. The following table shows the requirement levels of ROM or flash memory for an NMD and a DVR.
| ROM or flash memory requirement level | NMD | DVR |
|---|---|---|
Required |
16 MB |
32 MB |
Recommended |
32 MB |
64 MB |
See Also
Concepts
Hardware Architecture Diagram for Networked Media Devices
Other Resources
Performance Considerations for the Hardware Components of Networked Media Devices
CETK Tests
Core OS Services
Developing a Board Support Package
Developing a Device Driver
Developing an OEM Adaptation Layer