AWCTTYPA@UIAMVS.BITNET ("David A. Lyons") (01/17/89)
>Date: Mon, 16 Jan 89 14:57:00 CDT >From: MSER001%ECNCDC.BITNET@UICVM.UIC.EDU >Subject: ram chips >nec d41256c-15 chips will not work correctly with APW (apples >programers- workshop, but HM50256-15 or mcm6256BP10 will work, if you >are not using apw, you may get by with any 150ns chips, but if your >not certain, ask if you can take them back quickly if they don't work Hold on! That sounds _really_ fishy. If your RAM chips don't work with APW, there's something wrong--you're very lucky that they work with anything else. Most likely the stuff they _do_ work with is just not using any memory outside banks 0, 1, $e0, and $e1 (the motherboard memory). A long time ago (in the very early days of the GS), I had the very interesting experience of using a RAM card filled with flakey chips. The RAM worked okay _only_ if it was accessed constantly; for example, if you left the mouse cursor in one place for more than about 10 seconds, it would turn to garbage when you moved the mouse. Programs would launch successfully only if you entered their names quickly enough at the prompt of the crude program launcher available at that time. Assembly language programs would hang if you paused the listing for more than a couple seconds! The supplier informed us the chips were bad; they were eventually replaced and everything worked. Note that it _is_ possible for chips like that to pass the built-in self test! The self test doesn't test the RAM's ability to retain info over a period of time. If the chips are defective or, more likely, the wrong kind (RAS before CAS or CAS before RAS), you _won't_ get away with them for very long. A good test would be to set up a big /RAM5 (800K?), fill it with stuff (like a copy of a pretty full 800K disk), let it sit for a few minutes, and then verify that the two disks are still the same. (Don't just do a catalog! Actually check that the files are okay. Do a disk image comparison if you can.) --David A. Lyons bitnet: awcttypa@uiamvs DAL Systems CompuServe: 72177,3233 P.O. Box 287 GEnie mail: D.LYONS2 North Liberty, IA 52317 AppleLinkPE: Dave Lyons