IBM SBC-658 Computer Hardware User Manual


 
Chapter 3 Award BIOS Setup 61
The displayed configuration is based on the manufacturer's SETUP
DEFAULTS settings.
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 SDRAM.
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.
Because of the complexity and technical nature of some of the
options, not all of the options are described here.
SDRAM RAS-to-CAS Delay
This field lets you control the number of DCLKs between a Row
Activate command and a read or write command.
SDRAM RAS Precharge Time
The precharge time is the number of cycles it takes for the RAS to
accumulate its charge before DRAM refresh. If insufficient time is
allowed, refresh may be incomplete and the DRAM may fail to
retain data. This field applies only if synchronous DRAM is
installed in the system.
SDRAM CAS Latency Time
When synchronous DRAM is installed, you can control the
number of CLKs between when the SDRAMs sample a read
command and when the contoller samples read data from the
SDRAMs. Do not reset this field from the default value specified
by the system designer.