cc@sgfb.ssd.ray.com (Coday) (01/31/91)
I have a problem with a 386DX-20 Mylex motherboard that I'm thinking of buying (used) from a friend. If it's fixable, it'll be a good deal. I reduced the configuration to the minimum as follows: 1. Empty config.sys and autoexec.bat-- MSDOS 3.3 2. 2 floppies, 360K via a multi I/O card from my XT clone 3. EGA color The motherboard has 2 meg ram, and a 32K cache with an AMI BIOS. All power-on self-test works (also the rom-based diags) BUT about half the time, when you access a floppy to do a dir or whatever, you get "on-board parity error, address xxxxxx". This does not happen with a hard drive installed. All memory except for the cache has been replaced. All cards, cables and even the case has been swapped with no effect. My hypothesis is the DMA controller channel used for the floppies is interfer- ing with the channel used to refresh the dynamic RAM, but why does the hard drive work? Does it use a different channel? Naturally, the &*%#$ DMA is soldered in! But I know someone who can definitely de-solder it. Any ideas, suggestions? All help/advice greatly appreciated. thanks chuck