ULA Control Port
From SpecNext Wiki
| Number | PortNumber::$xxFE |
|---|---|
| Decimal | NumberDec:: |
| Short desc. | ShortDesc::Controls border color and base Spectrum audio settings. |
| Bit Mask | PortMask:: |
| Readable | Readable::No |
| Writable | Writable::Yes |
| Subsystem | Subsystem:: |
When written to, adjusts the border color and audio devices as follows:
| Bit | Function |
|---|---|
| 0-2 | Border color |
| 3 | Enable MIC output |
| 4 | Enable EAR output |
| 5-7 | Unused |
Reading the port with certain particular high bytes will read the keyboard (see Template:PortNo:$**FE. Bit 6 of the ULA byte is always the EAR input.