Advantech AIMB-250 user manual User’s Manual 3.5.3.4 DRAM RAS# to CAS# Delay, DRAM RAS# Precharge

User’s Manual

3.5.3.4 DRAM RAS# to CAS# Delay

This option allows you to insert a delay between the RAS (Row Address Strobe) and CAS (Column Address Strobe) signals. This delay occurs when the SDRAM is written to, read from or refreshed. Naturally, reducing the delay improves the performance of the SDRAM while increasing it reduces performance.

The choices: 2, 3.

3.5.3.5 DRAM RAS# Precharge

This option sets the number of cycles required for the RAS to accumulate its charge before the SDRAM refreshes. Reducing the precharge time to 2 improves SDRAM performance but if the precharge time of 2 is insufficient for the installed SDRAM, the SDRAM may not be refreshed properly and it may fail to retain data

So, for better SDRAM performance, set the SDRAM RAS Precharge Time to 2 but increase it to 3 if you face system stability issues after reducing the precharge time. The choices: 2, 3.

3.5.3.6 DRAM Data Integrity Mode

Select ECC if your memory module supports it. The memory controller will detect and correct single-bit soft memory errors. The memory controller will also be able to detect double-bit errors though it will not be able to correct them. This provides increased data integrity and system stability.

The choices: Non-ECC, ECC.

3.5.3.7 MGM Core Frequency

This field sets the frequency of the DRAM memory installed.

The choices: Auto Max 266MHz, 400/266/133/200 MHz, 400/200/100/200 MHz, 400/200/100/133 MHz, 400/266/133/267 MHz, 533/266/133/200 MHz, 533/266/133/266 MHz, 400/333/166/250 MHz, Auto Max 400/333 MHz, Auto Max 533/333 MHz.

3.5.3.8 System BIOS Cacheable

This feature is only valid when the system BIOS is shadowed. It enables or disables the caching of the system BIOS ROM at F0000h-FFFFFhvia the L2 cache. This greatly speeds up accesses to the system BIOS. However, this does not translate into better system performance because the OS does not need to access the system BIOS much. The choices: Disabled, Enabled.

3.5.3.9 Video BIOS Cacheable

This feature is only valid when the video BIOS is shadowed. It enables or disables the caching of the video BIOS ROM at C0000h-C7FFFhvia the L2 cache. This greatly speeds up accesses to the video BIOS. However, this does not translate into better system performance because the OS bypasses the BIOS using the graphics driver to access the video card's hardware directly.

The Choice: Enabled, Disabled.

AIMB-250 User’s Manual 71