How the original System 80 sound board makes sound

A 6503 processor (U1) with a 6530 combined ROM/RAM/I-O chip (U2) reads four select lines that pick up to 15 sounds. Its eight output lines feed a DAC (U3), whose output goes through C12 to an LM380 amplifier (U7). A 555 timer (U8) holds the processor in reset briefly at power-on.

Systems

• Gottlieb System 80

Related tips

• Fault-finding the original System 80 sound board
• The original sound board self-test only works with S1 and S2 set opposite
• Original sound board option switches S1 and S2
• Fitting the original sound board PROM
• No sound at all
• Distorted sound
• Original sound board connector A6-J1
• The wrong sounds or tunes play

Source: System 80 Service Manual, Gottlieb