This is 70-ns-parity-SIMM-problem-fixed in view mode; [Up]
Date: Sun 02-Jun-1991 20:40:57 From: federico@actisb.UUCP (Federico Heinz) Subject: 70 ns parity SIMM problem fixed! (through fishy technique) First of all, thanks to everybody who answered my query. I tried out every suggestion, but none of them worked. I finally tried out a crazy idea that popped up in my mind at about 3:00 am (while I was sleeping), and that solved the problem. As it turns out, you CAN mix parity and non-parity memory on the 68040 board, but only if you mix them THOROUGHLY. But first, the disclaimer: I don't know what I'm doing. I'm a software type, and although I can set up an RS232 cable, even that smells of black magic to me. Maybe what I'm about to suggest is slowly frying my motherboard as I type this, so try it out AT YOUR OWN RISK. If your system goes up in flames, don't blame me, I'm probably already crying over the ashes of my system. I found out that, if you mix parity and non-parity memory in a bank, the system will think that the whole bank is non-parity, and it then lives happy with the SIMM salad. I plugged the SIMMs in the following order (P=parity, N=non-parity): N N P P N N P P N N P P N N P P and the system booted fine. I'm puzzled about why this works, but it does. I'm even more bedazzled at the fact that the system wouldn't boot with 8 MB parity memory either---maybe both boards I tried out were broken after all, but I resist the idea. Maybe this should go in the FAQ? Not many people are asking it yet, but I fear they're coming.
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Marcel Waldvogel and Netfuture.ch.