
Сообщение от
NSC PC87306 писал(-а) на 20 странице PDF:
Bit 4 When this bit is zero the PC87306 can control two
floppy disk drives directly without an external decoder.
When this bit is one the two drive select signals
and two motor enable signals from the FDC are encoded
so that four floppy disk drives can be controlled
(see Table 2-3 and Figure 2-2 ). Controlling
four FDDs requires an external decoder. The pin
states shown in Table 2-3 are a direct result of the bit
patterns shown. All other bit patterns produce pin
states that should not be decoded to enable any
drive or motor.