Advanced Chipset Features - Advantech AIMB-251 Series User Manual

User's Manual
3.5.3

Advanced Chipset Features

This section allows you to configure the system based on the specific features of the
installed chipset. This chipset manages bus speeds and access to system memory
resources, such as DRAM and the external cache. It also coordinates communications
between the conventional ISA bus and the PCI bus. It must be stated that these items
should never need to be altered. The default settings have been chosen because they
provide the best operating conditions for your system. The only time you might consider
making any changes would be if you discovered that data was being lost while using your
system.
The first chipset settings deal with CPU access to dynamic random access memory
(DRAM). The default timings have been carefully chosen and should only be altered if data
is being lost. Such a scenario might well occur if your system had mixed speed DRAM
chips installed so that greater delays may be required to preserve the integrity of the data
held in the slower memory chips.
3.5.3.1 DRAM Timing Selectable
This item allows you to select the DRAM timing value by SPD data or Manual by yourself.
The choices: Manual, By SPD.
3.5.3.2 CAS Latency Time
This item controls the time delay (in clock cycles - CLKs) that passes before the SDRAM
starts to carry out a read command after receiving it. This also determines the number of
CLKs for the completion of the first part of a burst transfer. In other words, the lower the
latency, the faster the transaction.
The choices: 2, 2.5.
3.5.3.3 Active to Precharge Delay
This item is the minimum delay time between Active and Precharge
The choices: 5, 6, 7.
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