I am concerned about getting the same length to all RAM chips (the output is equidistant to all inputs of the different chips) I heard somewhere that a rule of thumb is that you get .18 nanoseconds of time delay for every inch of tracing. Is this accurate? Is it safe to use this when making decisions on differences in trace lengths? For example, the RAM is clocked at 100 MHz, and one RAM has an extra .88 inches of tracing for some of its data lines than its others. Using the rule of thumb, that would be about .16 nanoseconds delay to the longer traced data lines, and .16 nanoseconds is probably negligible relative to the 10 nanosecond clock cycle of the RAM (i know I would need to take into consideration the time delay on the clock trace as well). Does this sound reasonable? Also, where would someone get a number like .18 ns /inch? I did the conversion and this is considerably slower than the speed of light, a little less than half the speed at 1.41 million meters /sec. How would a trace slow the signal by this much?