I think I have found the answer here;
http://www.l8r.net/technical/wblock/a1200/a1200.htmlQ. I've seen SIMMs with speed ratings of 60, 70, and 80 ns. What does this mean, and which do I need?
A. These numbers rate the speed at which the SIMM can be reliably operated. A 60 ns SIMM is the fastest currently available at reasonable prices. To keep a processor running at its fastest rate, the memory needs to be able to keep up with it; the speed of your processor determines the minimum memory speed needed. For an A1200 with just a RAM expansion board, 80 ns SIMMs are fast enough. With an accelerator, it depends on how fast the processor is going, so you'll need to check the manual. (Note: many boards let you use slower SIMMs with them by enabling a "wait state," which forces the processor to slow down to the SIMM's speed, and allows you to use cheaper, slower SIMMs. For instance, an accelator may say that it requires 70 ns SIMMs to run at "zero wait states," but will operate with an 80 ns SIMM (slower) if you set a jumper to enable a wait state.)
