🚀 go-pugleaf

In <4kmvo1$ol3@news.pathcom.com>, stonet@pathcom.com (stonet) writes:
>>Isn't 70 ns a velocity measurement, therefore the larger the number the 
>faster the access....
>

To make it simple (like that's possible<g>) 70ns refers to the amount of time 
it takes the RAM to respond to requests for data reads or writes. 
From the point of view of the CPU, its the amount of time that the CPU must 
spend at that device to either read or write data. Therefore, 60ns is faster 
than 70ns, since the CPU get/put data from/to that device 10ns quicker, 
allowing the CPU to get on with the instruction faster.

If the RAM access speed is too slow, then the BIOS must be set to provide 
what are called wait-states. A wait-state is used to tell the CPU that the 
RAM (or any other device) is too slow and that the CPU will have to wait
for a pre-determined time in order for the accessed device to 'catch-up' to 
the CPU.

If your system uses slow RAM, it must insert wait-states, which by their
definition, tell the CPU to 'wait for me' Obviously, this will impact the 
performance of the system. 

How fast is fast, and how slow is slow? That can only be answered by 
the individual system clocks and RAM speeds. 

Usually, and I say that with a great deal of trepidation <g>, you will find
70ns devices in a 486 machine, while the higher speed pentiums will
be found with 60ns. There are always exceptions, but its something to keep
in mind if you intend to buy RAM for your 486, with the intent to one day
upgrade to a faster pentium. In that case, you would want to get 60ns so that
when you upgrade the CPU, you won't have to turn on any wait-states.

Did I say that clearly???

John