ACIA driver

Manage I/O from an asynchronous communication interface adapter
(ACIA). provides "(emit)" to put c char on the ACIA as well as
an input buffer from which a provided "(key)" reads. You have
to call "~ACIA" on interrupt for this module to work well.

CONFIGURATION

ACIA_CTL: IO port for the ACIA's control registers
ACIA_IO: IO port for the ACIA's data registers
ACIA_MEM: Address in memory that can be used variables shared
          with ACIA's native words. 8 bytes used.

The whole driver is cross-compilable and is loaded with
"582 LOAD"
