bsouther@uok.UUCP (10/28/83)
#R:isrnix:9600001:uok:10700001:37777777600:1473 uok!bsouther Oct 26 03:15:00 1983 I have never experienced the problems you have described (exactly), but there are certain things that are inherantly bad about using ANY memory expansion on the zx/81: 1) The interface connector on the zx/81 is electronically unsound when it comes to reliability. You can't firmly attach your Memopak or other expansion without lots of tape, and even if you can secure it, the contacts are prone to oxidation and subsequent loss of electrical contact after a short time. 2) The memory decoding on a zx/81 is tricky, with the bulk of the decoding done by the computer's "do- everything-including-pick-your-nose" chip. It appears that this chip was designed to work at 100% efficiency iff there is no additional memory (beyond 2K). If any expansion is done (of any sort, including just adding a printer), this chip tends to "drop" data somewhere off in a bit bucket at random intervals. Perhaps your problems are ROM based, but more likely you are just experiencing localized troubles whereas the rest of us haven't been able to pinpoint one specific event which causes data losses. I have no help for you, but just thought it might make it easier on you to know that I've yet to find anyone who has a zx with expansion that has NOT experienced (relatively) high data dropouts. If you CAN find some way around this annoying occurance, *PLEASE* post it so the rest of us can benefit, too! Brad Southers Univ. of Oklahoma uok!bsouther