Hi To get any sort of useful memory density we’ll need to use the Pseudo-SRAMs at a minimum. Those are only available in TSOP-44 which is SMT but manageable. The alternative is BGA packages which are entirely unmanageable unless you have the IR heat lamp or soldering oven. Both are specialized equipment so the TSOP-44 PSRAMs are a viable if difficult option. http://www.digikey.com/product-detail/en/IS66WV51216BLL-55TLI/IS66WV51216BLL-55TLI-ND/1981805 We might be able to use as many as 16 PSRAMs to get to a 16MB board. That seems like the next logical step once we show the 4MB SRAM board is working. Then it is all DRAM based solutions and that is going to get ugly. I don’t particularly like SMT but recognize there may be no other choices in some instances. Let use them sparingly when needed as needed. Thanks and have a nice day! From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of John Monahan Could use these, in general I like to stick to DIP chips with sockets (and a Zener in this case). Surface mount tend to be a little tricky for some. There is plenty of space on this board. There are DIP “level changers” also, but outfits like Jameco don’t stock them. As a general question, how do people feel about surface mount chips? I currently working on plans for a 80386 RAM board where capacity is an issue. Do most people fee that could solder SM RAM chips to a board. Really would increase board capacity for pseudo-RAM chips. John John Monahan Ph.D e-mail: mon...@vitasoft.org Text: mon...@txt.att.net From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of yoda why not use 74lvxxx logic to interface to the lava board ? - it does the protection and is 5V tolerant - it has been used in propeller interfaces for the same thing and makes the parts count a lot smaller Hi Paul! Thanks! Yes, the 3.3VDC Zener diodes are added after the 100 ohm |