21. DIGITAL I/O PORTS

Helios has two groups of digital I/O ports and one digital interrupt circuit:

• 3 8-bit ports named A, B, and C are included in the data acquisition circuit on the AV model and are available on connector J17 on that model.

• 2 8-bit ports named D and E are provided by the digital I/O circuit integrated into the Vortex processor and are available on connector J7 on all models.

• An interrupt on the ISA bus may be triggered using the EXTTRIG pin on connector J17 on the AV model