Multiple studies of memory reliability (DRAM) show that parity memory is more prone to failure than non-parity memory. If you want reliability, you have to go to something like Error Correcting Codes (ECC) like the big boys use. We had 39-bit memory on a 32-bit VAX (11/750) because the extra seven bits let you *detect* two faulty bits and *correct* a single bit failure. The Sun Enterprise servers I babysit have ECC memory - we used to get one or two failures in the machine room per year, but they were logged and corrected without any loss of data. My Alpha board (AXP-133 "no-name" board) uses 72-pin *parity* SIMMs in pairs to implement ECC on a 64-bit memory bit. The problem with parity is that yes, you do know that you had a failure, but now you have 9 bits that might fail, not 8, raising your risk by 12%. DRAM failures are more often total rather than intermittent. A memory test at power-up is a better insurance policy than relying on parity to save your butt. I did have the parity circuit on a PeeCee cough up a lung once... it was even a five-slot original PC (256K on M.B.). We were using it into the 90's because it was merely the terminal for a Northwest Instruments logic/CPU analyzer that we used to check for problems in our MC68000-based serial boards. One day, the PC would not come up. Because everything was socketed and because I owned an IC tester, we got a bottom-of-the-totem-pole tech grunt to pull each chip and test it. It was a faulty 4164. Labor costs: $25. Parts cost: $0.60 for a part we stocked thousands of for one of our older products. I still have the machine. It still works. I wish I had the invoice for that CPU; the company bought it new in 1981, around $5K, I know, but I'd like to know the exact figure. Bottom line: Apple not using parity is not a reason to trash the Mac. How many PCs have parity since we moved to EDO and SDRAM? It's extra cost and extra complexity and extra possibilities for failure. Unless you can correct the failure, it's not mathematically worth the extra expense and reduced reliability. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com