I just recently asked the same question. After receiving no responses, I did some searching of my own and this was the best list I found. All of them are very tiny (2K FRAM is largest RAM). I still find it hard to believe that no one is making such a thing so may be I'm missing it. If not, the best bet seems to be a shift register connected to a standard parallel RAM. SPI Memories (EEPROM, FRAM, NOVRAM, and SRAM) ========================================= (# before a part number indicates a new listing as of 04/12/95) Atmel AT25C01 1K bit EEPROM AT25C02 2K " " AT25C04 4K " " AT45D081 8M FLASH Catalyst CAT33C704 3-volt CAT35C704 CAT35C704 4K " EEPROM with security CAT64LC10 1K " " CAT64LC20 2K " " CAT64LC40 4K " " Intersil CDP68HC68R1 1K " SRAM http://www.intersil.com/data/fn/fn1/fn1544/index.asp CDP68HC68R2 2K " " Motorola MCM2814 2K " EEPROM National NM25C04 4K " " Ramtron FM2504(0/1) 4K " FRAM FM2516(0/1) 16K " " Xicor X25020 2K " EEPROM X25C02 2K " " X25040 4K " " X25043 4K " " with reset supervisor X25080 8K " " X25160 16K " " X25320 32K " " X25640 64K " " X25128 128K " " X25401 256 " NOVRAM Parallel Hitachi http://www.halsp.hitachi.com/ HM62256 distributed by http://www.Jameco.com Toshiba http://doc.semicon.toshiba.co.jp/indexus.htm TC551001 distributed by http://www.Digikey.com Serial The SGS M48T02 is a TimeKeeper RAM that has 2 kBytes of RAM, RTC, and battery on the chip Dallas Semiconductor has a DS2404 EconoRAM Time Chip with RTC, 512 bytes RAM http://www.dalsemi.com/DocControl/PDFs/2404.pdf Phillips PCF8570 256 x 8-bit static low-voltage RAM with IÓC-bus interface http://www.semiconductors.com/pip/PCF8570 James Newton, webmaster http://get.to/techref jamesnewton@geocities.com 1-619-652-0593 phoneŹ -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Nicholas Irias Sent: Wednesday, August 18, 1999 7:03 PM To: PICLIST@MITVMA.MIT.EDU Subject: SPI DRAM I want to set up a memory system to allow two PICs to exchange several data values. I am considering using an SPI memory chip along with the necessary switching to make sure only one PIC tries to access the memory chip at a time. My reason for considering this scheme is that each PIC needs to spend most of its time tending to some very time-sensitive tasks, so direct communication between the PICs is difficult/impossible. My question: Is there such a thing as an SPI DRAM? The closest thing I have found so far is an SPI FRAM, which is fast enough is limited to only 10^10 read or write accesses. SPI EEPROMs are even slower and have even fewer read-write cycles before they experience unacceptable errors. My second question: Am I re-inventing the wheel? Maybe there's some sort of single chip solution for what I'm trying to do, like maybe a 256 byte dual ported SPI chip? thanks -Nicholas