At 05:22 PM 06/27/1989 Mandi Wilson wrote:
>
> Can someone please tell me what [CAS latency timing]
> means and how do I find out what number I should use?


Mandi:

"CAS latency" refers to the amount of time required to complete one CAS
memory operation before another can begin. The timing is measured in clock
cycles.  CAS -- or Column Access Strobe -- is the process of setting up the
column address in the memory matrix (data is stored in a cell which is the
intersection of a Column and a Row) for the read/write operation. There is
also column precharge time period included in CAS latency. Obviously, there
is also a Row Address Strobe ("RAS").

The CAS value may be set in CMOS. The lower the timing, the faster the
operation. Thus, adjusting the setting from 3 to 2 will speed up access
time in a read operation so data is available on the data bus one clock
cycle faster. Sometimes there is a different CAS method for read and write
operations so you have to set one time value for reads and a different one
for writes.

Setting the rate too low may hang your system so, to recover, you would
have use the clear CMOS jumper (or remove the battery) to reset all
settings including CAS to their defaults.  Before changing the CAS timing,
you should record all your current CMOS settings in the event you have to
clear CMOS and re-enter values.

The proper setting depends on your particular RAM, motherboard and CPU, so
you'd have to supply specific information. You should refer to the manual,
which may elucidate the issue.

Regards,

John Chin

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