XWUU@PURCCVM.BITNET (12/24/90)
I am ready to upgrade my 1764 REU to (at least) 512K. I've read the articles about how to do it and am anxious to get hold of geoWizard for maximun GEOS power. I know that I need eight 256Kx1 DRAM chips to upgrade to 512K, but which ones? I have a list in front of me that shows 256Kx1 DRAMS for a little over $2 for one labelled 150ns (nanosecond) to one at just under $5 for 60ns operation. Do I need to be concerned about the "speed," or should I just go for the least expensive? A second question: Instructions in "Beyond 512kb" by Andrew E. Mileski says that to bump my REU over 512K requires that I "piggy-back" the DRAM IC's on top of the chips mounted to the REU's circuit board. Do I simply place the new chips on the back of the old ones and stick the pins down along side of the old pins? Will both pins neatly fit the holes in the circuit board (or socket)? I can easily see one additional row of IC's for each of the two banks on the REU providing 1Meg, but to get 2Meg does one simply add yet another chip to each stack? Doesn't that get a little TALL on the board? Where do the pins on this 3rd row go? How do you attach them to the previous chips? Yes, I know...questions, questions, questions. But some of you have done the conversion and we'd like to know how you pulled it off. The 512K expansion looks like a cinch...the 1Meg-2Meg I'm not so sure about. How 'bout it folks. Any tips, hints, comments? Kirk A. Janowiak XWUU@PURCCVM P.S. HAPPY HOLIDAYS!!
treesh@bach.helios.nd.edu (12/29/90)
DISCLAIMER: Im speaking on strictly a theory, not from acutaly expirence with high memory REU's. The piggy backing of the ram chips makes sence, but there should be one pin that you do not piggy back, this will proabaly be the CS line. This line is whats used to select this chip durring memrory mutliplexing. As for the chips being TALL, they are proabaly replaced with 1 MEG DRAM chips, and in the 2 meg configuration, they are then 1 MEG piggy-backed. ctfm