> On Aug 30, 2016, at 8:15 PM, Eric Smith <space...@gmail.com> wrote: > > On Tue, Aug 30, 2016 at 1:28 PM, Paul Koning <paulkon...@comcast.net> wrote: >> Another possibility would be a current (not surplus) DRAM device such as a >> 1M x 16 chip, plus a couple of level shifters to go between the 3.3 V it >> likes and the 5V logic of the Pro. > > WARNING: Most recent 1Mx16 DRAM devices are synchronous DRAM (and > usually DDR of some description), which are NOT EVEN CLOSE to being > electrically compatible with legacy 16-pin DRAMs, nor even the 1 Mbit > and 4 Mbit legacy DRAMs. > > Most of the ones that aren't synchronous are 3.3V parts, and won't > work reliably if at all in a 5V system without the level shifters Paul > mentioned. I commonly use 74LVC245 buffers between 5V and 3.3V logic, > when the 5V logic doesn't require a full 5V swing (e.g., Voh min of > 2.0V for TTL-compatible parts).
Yes, the one I saw when I made that comment is an MSM51V18165F by Lapis, a 1M by 16 "fast page mode" EDO DRAM. > It does appear that ISSI still makes some 5V 1Mx16 non-synchronous > DRAMs in either EDO or Fast Page Mode. There's a reasonable chance > that the 5V Fast Page Mode devices would work for replacing legacy > DRAM, and wouldn't require any level shifting. That would be interesting to try. paul