wzg90@TTACS1.TTU.EDU ("NGUYEN, TIEN") (04/22/89)
I have a 520ST (3 years old) and have opened it up many times in the past. Only recently did I realize something that may be important: the 520ST uses 150ns 256Kx1 DRAMs.... This by itself isn't a problem, but the CPU runs at 8MHz, which translates to 125ns per clock cycle. Well, to make things short, this means that the ST is running its RAM with one wait state, correct? Unfortunately, at 4 clock cycles per memory hit (average), this translates to a 20% decrease in performance compared to what it could be with no wait states... Well, it'd be pretty nice to have that extra 20% performance, so the question is: does the Mega STs use the same type of MMU that is used in the 520? The MMU is, in all likelihood, responsible for generating the wait state cycle, so it seems that if the Mega is using faster RAMs (say, 100ns so that there'd be an ample 25ns for address decoding and buffering) and the MMU ISN'T generating a wait state cycle, then I should be able to replace my RAM with 100ns RAM and put the Mega MMU in and everything will be 20% faster. Have I missed anything?? Funny that I've never heard mention of this on the net before. Am I missing something vital here?? Tien Nguyen wzg90@ttacs1.ttu.edu