Edito: Extracto de la página de referencia de WOS
The ULA chip uses the same pin (28) for all of the MIC socket, EAR socket and the internal speaker, so bits 3 and 4 of an OUT to Port 0xfe will affect bit 6 as read by an IN from Port 0xfe. The difference between Issue 2 and 3 machines is:
Código: Seleccionar todo
Value output to bit: 4 3 | Iss 2 Iss 3 Iss 2 V Iss 3 V
1 1 | 1 1 3.79 3.70
1 0 | 1 1 3.66 3.56
0 1 | 1 0 0.73 0.66
0 0 | 0 0 0.39 0.34