Look at the part number on the chips. There is a "-" and
then a number, and that number is the clock time in
nanoseconds. The inverse of that time gives the clock rate.
You can see some examples here. Notice how the -75 or 7.5ns
is 133MHz or PC133. I cannot find any examples of datasheets
for PC100, but would assume there would be a similar
relationship between the "dash-number" and the speed.
http://web.archive.org/web/20031211...roducts/dram/sdram/partlist.aspx?density=64Mb
HTH,
Paul