bitfixer
Veteran Member
Hi all,
Small programming question for the PET. The 'Diag Sense' line on the PET userport is connected to pin 9, PA7 on one of the 6520s. This line is an input by default, but the schematics I've seen indicate this line as bidirectional. Anyone know if it is possible to set this line as an output, and if so, how to write to it?
The purpose of this is that for a demo I'm working on, the CB2 line is used for handshaking while reading data in from the user port, and on the models with a speaker, this causes an annoying buzzing sound. The diag line and the CB2 line go to a nand gate and the output of that goes to the speaker, so if you ground the diag line, the buzzing stops. The workaround I had was to ground the diag line on the userport, but only after bootup, since the PET won't boot if you hold that line low at startup. Would be convenient if I could just set that line to output and write 0 to it.
Thanks for the help.
Small programming question for the PET. The 'Diag Sense' line on the PET userport is connected to pin 9, PA7 on one of the 6520s. This line is an input by default, but the schematics I've seen indicate this line as bidirectional. Anyone know if it is possible to set this line as an output, and if so, how to write to it?
The purpose of this is that for a demo I'm working on, the CB2 line is used for handshaking while reading data in from the user port, and on the models with a speaker, this causes an annoying buzzing sound. The diag line and the CB2 line go to a nand gate and the output of that goes to the speaker, so if you ground the diag line, the buzzing stops. The workaround I had was to ground the diag line on the userport, but only after bootup, since the PET won't boot if you hold that line low at startup. Would be convenient if I could just set that line to output and write 0 to it.
Thanks for the help.