'1284P has 16K SRAM, could store it there if the data needs to be varied by the code - or captured & played back.
This duemilanove style 1284P board I offer can do that (duemilanove style because it uses FTDI chip vs 8U2/16U2 chip for USB/Serial). The USB/Serial can be on-board as pictured here, or an off-board FTDI Basic(or similar) can be connected to a header that would be installed in place of the module.
I recently used it in a project with a 14500 byte array to do similar, I blasted the data out at 8 MHz rate into a large bank of shift registers.
http://www.crossroadsfencing.com/BobuinoRev17/
