The DIO-48 Provides 48 TTL digital I/O lines, and one 16- bit counter. The DIO-48 emulates 8255 mode 0 and has an increased output current of 15mA (source) and 64mA (sink). This allows it to control LED, relay, etc. The DIO-48 consists of six 8-bit bi-directional ports and 3 input lines for interrupt enable and counter. The 8-bit ports are named port A(PA), port B(PB), and port C(PC). Port C can be split into two four bits. All ports are configured as inputs upon power-up or reset. The base address is selectable from 200 to 3FF hex. The interrupt signal can be connected to any of the interrupt levels 2 through 7.