Tinkering with sound on a Superboard
Posted: Mon Nov 27, 2023 11:43 am
To get a little bit more entertainment out of a SB600 machine, I lately updated my Emulator to allow different sound output options.
- Sound coming from the 4 or 8 bit onboard DAC (R–2R resistor ladder network)
- Sound from the RTS line of ACIA (as implemented in the Aardvark C1S Roms)
- Sound from a SN76489AN programmable sound generator (PSG with 3 channels pulse noise)
The Emulator is available in 32 or 64 bit and includes a new PRG load and save function to quickly get Basic or machine code programs (or combinations) into the machine.
The SN76489AN programmable sound generator was used in many early 70's home computers. The Christmas.prg shows, how the PSG can be programmed in Basic. Within the .ini configuration file, address location of the SN76489AN can be adapted to existing programs.
For true 4 or 8 bit onboard DAC sound ($DF00 keyboard latch), you can enable and disable the output as defined by the Rev D 600 board by poking a 16(on) or 0(off) to address $D800. After RESET (F12) the sound is automatically disabled to avoid the keyboard scanning routine to be audible.
In other systems, the RTS line on the 6850 was also used as a simple 1-bit sound output. This is available as well.
So a lot of different options to generate music. Attached some program samples to demo the new sound feature.
- Sound coming from the 4 or 8 bit onboard DAC (R–2R resistor ladder network)
- Sound from the RTS line of ACIA (as implemented in the Aardvark C1S Roms)
- Sound from a SN76489AN programmable sound generator (PSG with 3 channels pulse noise)
The Emulator is available in 32 or 64 bit and includes a new PRG load and save function to quickly get Basic or machine code programs (or combinations) into the machine.
The SN76489AN programmable sound generator was used in many early 70's home computers. The Christmas.prg shows, how the PSG can be programmed in Basic. Within the .ini configuration file, address location of the SN76489AN can be adapted to existing programs.
For true 4 or 8 bit onboard DAC sound ($DF00 keyboard latch), you can enable and disable the output as defined by the Rev D 600 board by poking a 16(on) or 0(off) to address $D800. After RESET (F12) the sound is automatically disabled to avoid the keyboard scanning routine to be audible.
In other systems, the RTS line on the 6850 was also used as a simple 1-bit sound output. This is available as well.
So a lot of different options to generate music. Attached some program samples to demo the new sound feature.