Aplex APC-3580, User Manual

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APC-3580 User Manual 78

Configure DRAM Timing by SPD [Enabled]
Use the
Configure DRAM Timing by SPD
option to determine if the system uses the SPD
(Serial Presence Detect) EEPROM to configure the DRAM timing. The SPD EEPROM contains
all necessary DIMM specifications including the speed of the individual components such as CAS
and bank cycle time as well as valid settings for the module and the manufacturer's code. The
SPD enables the BIOS to read the spec sheet of the DIMMs on boot-up and then adjust the
memory timing parameters accordingly.

Disabled
DRAM timing parameters are manually set using the DRAM
sub-items

Enabled DEFAULT
DRAM timing parameter are set according to the
DRAM Serial Presence Detect (SPD)
If the
Configure DRAM Timing by SPD
option is disabled, the following configuration options
appear.
ٛ
 DRAM CAS# Latency [3]
ٛ
 DRAM RAS# to CAS# Delay [5 DRAM Clocks]
ٛ
 DRAM RAS# Precharge [5 DRAM Clocks]
ٛ  DRAM RAS# Activate to Precha [15 DRAM Clocks]

Memory Hole [Disabled]
Use the
Memory Hole
option to reserve memory space between 15MB and 16MB for ISA
expansion cards that require a specified area of memory to work properly. If an older ISA
expansion card is used, please refer to the documentation that came with the card to see if it is
necessary to reserve the space.

Disabled DEFAUL
T Memory is not reserved for ISA expansion cards

15MB – 16M
B Between 15MB and 16MB of memory is reserved for ISA
expansion cards