DESCRIPTION:

This board provides 2 identical chips that each emulate an industry standard 8255 Programmable Peripheral interface (PPI). Each PPI offers 3 ports: PA, PB, and PC. PC is subdivided into 2 nibble-wide (4-bit) ports. PCI-7248 has a programmable timer counter that can generate periodic interrupts to the host processor. The timer/counter chipset is 82C54, which includes three 16-bit counters, at 2 MHz clock input. One counter is used as an event counter. The remaining two are cascaded together making a 32-bit timer.