Post by thread:[PIC]: [OT]: External SRAM on PIC (or AVR)

I have found 128Kx8 SRAMs, or at least evidence of their existence, but I can't seem to find any in stock (or at least with a <8 week delivery time). I think I'm going to have to use 2 32K*8 SRAMs and use a little bit of decoding logic. Digikey has some Toshiba 128K parts in stock, but they aren't fast enough to operate without a wait state (on the AVR). Pioneer appears to have some 62C256 parts from ISSI. (for now) Matt {Original Message removed}

My own mistake there, I misread the data sheet and thought they were incompatible- the /OE and /RD are, in fact, the same thing. I'm going to have to overlap the internal and external memory, since I want to get as much RAM on the device as I can.- I lose 608 RAM locations, Oh well... I've decided to use 2 32Kx8 parts- the address decoding is simple- just an inverter. Unfortunately the 62C256 only has a /CS input- some other SRAMS (which either I can't get in time, or aren't fast enough) have both a /CS and a CS, so the inverter would be unnecessary. This design is low volume, so having an extra gate is not a terrible thing. Matt {Original Message removed}

Matt Bennett wrote: >I have found 128Kx8 SRAMs, or at least evidence of their existence, but I >can't seem to find any in stock (or at least with a <8 week delivery time). >I think I'm going to have to use 2 32K*8 SRAMs and use a little bit of >decoding logic. Digikey has some Toshiba 128K parts in stock, but they >aren't fast enough to operate without a wait state (on the AVR). Pioneer >appears to have some 62C256 parts from ISSI. (for now) > Jameco has both fast Cypress 32Kx8 SRAMs [0.3"] and the slower std 0.6" type. Also, if you have a spare line on your AVR you can separate the /CS lines for the 2 SRAM chips and forgo the need for external decoding logic. Cheers, - Dan Michaels Oricom Technologies ===================

Matt Bennett wrote: >I have found 128Kx8 SRAMs, or at least evidence of their existence, but I >can't seem to find any in stock (or at least with a <8 week delivery time). >I think I'm going to have to use 2 32K*8 SRAMs and use a little bit of >decoding logic. Digikey has some Toshiba 128K parts in stock, but they >aren't fast enough to operate without a wait state (on the AVR). Pioneer >appears to have some 62C256 parts from ISSI. (for now) > Also, checkout the SRAM modules sold by http://www.accutekmicro.com Cheers, - Dan Michaels Oricom Technologies ===================