At 02:44 PM 7/22/99 +1000, you wrote: >Microchip has an application note on attaching SRAM to a PIC16CXX (TB011). >This application note shows a circuit in which 2x256K(32Kx8) chips are >hooked up using a 16-bit address bus multiplexed with an 8-bit data bus >(total of 19 pins). > >There is also an application note on connecting external memory to a >PIC17xxx via it's inbuilt bus (TB005). > >The opnly limitation is the size of address bus you can manage. Obviously >you can get a very large bus with lots of multiplexing but this adds >components and complexity (both to circuit and to code). I'm also not sure >about whether timing would become an issue with more chips. > >However, it is certainly possible to hook up at least 256K to almost any PIC >with an efficient use of pins. I'm planning on using a serial latch to latch a starting count into a counter, then pulse the counter to step through the addresses--which are the parallel outputs of the counter--8, 16, 24, 32 or whatever address's are needed. simple, clean, and very efficient on PIC pins. Suggest standardizing of VLC parts as they will run on 3 or 5 volt power and accept inputs to 7 volts. Great logic family. and very low power., Enjoy Kelly **************************************************************************** ******** All legitimate attachments to this email will be clearly identified in the text. William K. Borsum, P.E. OEM Dataloggers and Instrumentation Systems &