Post by binarystar on May 16, 2014 7:01:49 GMT -5
I noticed something strange with one of the Vectrex BIOS functions the other day. I haven't had a dig into the BIOS disassembly yet, just wondering if anyone else had encountered this?
If Y axis on 2nd controller is enabled, you get noise/buzzing coming over the vectrex speaker when the joystick is moved. This buzzing happens both on the emulator and on Vectrex itself. Even if the sound-chip is completely muted the buzz still occurs. Both analog sticks work as expected, only you get this low frequency buzzing noise on the speaker. It fades in/out when moving the second analog stick up and down.
This 'bug' only happens on the call of Joy_Analog.
I can only assume there is a 'bug' in the Y axis read code which interferes with what the sound chip is doing?
I have attached a simple example file to demonstrate this buzzing as well as a binary. Can anyone confirm this happens on the later 'nobuzz' Vectrex BIOS?
If Y axis on 2nd controller is enabled, you get noise/buzzing coming over the vectrex speaker when the joystick is moved. This buzzing happens both on the emulator and on Vectrex itself. Even if the sound-chip is completely muted the buzz still occurs. Both analog sticks work as expected, only you get this low frequency buzzing noise on the speaker. It fades in/out when moving the second analog stick up and down.
This 'bug' only happens on the call of Joy_Analog.
I can only assume there is a 'bug' in the Y axis read code which interferes with what the sound chip is doing?
I have attached a simple example file to demonstrate this buzzing as well as a binary. Can anyone confirm this happens on the later 'nobuzz' Vectrex BIOS?