This reduces the number of communication pins on the module to just two: a clock signal and a data signal. The SPD EEPROM firmware is accessed using SMBus, a variant of the I☬ protocol. For example, the SPD data on an SDRAM module might provide information about the CAS latency so the system can set this correctly without user intervention. Devices utilizing the memory automatically determine key parameters of the module by reading this information. These bytes contain timing parameters, manufacturer, serial number and other useful information about the module. 2.3 AMD Extended Profiles for Overclocking (EXPO)įor a memory module to support SPD, the JEDEC standards require that certain parameters be in the lower 128 bytes of an EEPROM located on the memory module.

2.1 Enhanced Performance Profiles (EPP).It may be possible to control how the computer uses the memory SPD data-to choose settings, selectively modify memory timings, or possibly to completely override the SPD data (see overclocking). In most cases, there is a special optional procedure for accessing BIOS parameters, to view and potentially make changes in settings. Some computers adapt to hardware changes completely automatically. SPD is a memory hardware feature that makes it possible for the computer to know what memory is present, and what memory timings to use to access the memory. Since about the mid-1990s, this process includes automatically configuring the hardware currently present. When an ordinary modern computer is turned on, it starts by doing a power-on self-test (POST). Earlier 72-pin SIMMs included five pins that provided five bits of parallel presence detect (PPD) data, but the 168-pin DIMM standard changed to a serial presence detect to encode much more information. In computing, serial presence detect ( SPD) is a standardized way to automatically access information about a memory module. Standardized way to automatically access information about a memory module

Serial number magic lines download