cotner@BRAHMS.BERKELEY.EDU (Carl Cotner) (07/27/88)
Am I having trouble dividing, or is there something else that I'm missing? Here's what I'm referring to: I have a 12MHz AT motherboard (clone), and the paltry instruction manual that came with it stated that at 12Mhz, I can use 100ns chips and get 0 wait states. In that same manual it states that the 10Mhz motherboard can achive 0 wait states by using 80ns chips. This seems somewhat fishy to me. Since 1/12Mhz = 83ns, I would expect that in order to do a memory seek in one machine cycle, I would need RAM chips faster than 83ns, i.e. 80ns or less. Similarly, since 1/10Mhz = 100ns, The 10Mhz board must use 100ns chips. How come they can get away with 80 and 100ns? BTW, I was also wondering if any of you out there have ever tried to install slower memory chips on a turbo motherboard. Since RAM prices are kind of high right now, I thought I'd salvage some 120ns RAM from a spare AT board and install them on my 6/12MHz motherboard. I set the jumper on the board so that it would boot up in 6 MHz mode rather than 12. Despite this slower setting, I received several memory parity errors during setup. Do I have a defective motherboard, or is the clock still operating at 12MHz for some portions of the board? The motherboard is called a SAM/12, if that's of any help. Just a few thoughts. I'd appreciate any answers though. cc