Microchip Technology ay-3-8910 - Interfacing to the PIC 1650

4.6 Fig. 19 shows the schematic of an AY-3-8910 demonstrator circuit.
Interfacing
This configuration uses a PIC 1650 as the main controller in the
circuit. The PIC 1650 is used to scan the keyboard, fetch data from
the PROM S , writedata to the AY-3-8910 and provide the timing for the
to the PIC 1650
AY-3-8910.
The interfacing is direct since the PIC 1650 and the AY-3-8910
operate with compatible supplies and input/output voltages.
This particular schematic illustrates how a microcomputer with
additional memory can produce a stand-alone music and sound
effects circuit. The circuit as shown operates with manual keyboard
selections.
As Fig. 19 shows, the design for the interface connects directly to the
output pins of the 1650 and the BC1, BC2, BDIR pins. The software
then has the responsibility of manipulating these signals to signal the
PSG to perform the proper address latch, read or write operations.
The program routine in this section illustrates code which is used in a
hand-held demonstrator unit. This demonstration unit illustrates the
range of PSG capabilities, including music, sound effects and I/O
control. Note that the generalized routines perform the address
latching before every read for convenience.
The “READ ROM” routine illustrates use of the generalized read and
write routines to access the outside world through the PSG to read
and write.