Look for external serial memory (http://www.picbasic.co.uk/forum/showthread.php?t=12766).

In particular look at serial (SPI or I2C) EEPs (http://www.microchip.com/stellent/id...GE&nodeId=2697), SRAM (http://www.microchip.com/stellent/id...GE&nodeId=2698), or FRAM (http://www.ramtron.com/products/nonv...ry/serial.aspx).