henry@ginger.sri.com (Henry A. Pasternack) (09/01/90)
I am planning on building a more ambitious system now that my single board 68000 is working well. I'll be using a 68030 with four to sixteen megabytes of DRAM and a SCSI drive. I have a couple of questions that someone might be able to help me with. 1) Memory I'm planning on using one of the newer National DRAM controller chips for my memory. This machine supports four separate RAS lines with independent RAS precharge counters, allowing efficient interleaved access. Upon reflection, interleaved access and nibble mode burst access seem to be at odds with one another. Can someone comment briefly on memory interface strategies for the 68030? What's more important, to support the cache burst, or to have fast random access? I'd like to buy cheap SIMM memory. How can I tell if the $65/Mb type SIMM's support the access modes I require? Any other comments on selecting memory devices? Is it worthwhile implementing parity checking or EDAC? How difficult is this to do? Is there a performance tradeoff? 2) Disks I know this subject has come up before. Maybe we can address it again. What is the best way to interface a SCSI disk? Can I just buy a plain vanilla SCSI drive, or do the interfaces vary, say, between Mac and PC style drives? What's a good SCSI controller chip? How complicated must the driver software be. Thanks for any and all information. -Henry