ICW4
and
OCW3
A total of 56 bytes need to be written,
and its port is only
0x20,0x21
0xa0,0xa1
four ports, these ports are also one byte, how to write these 56 bytes into these four ports?
ICW4
and
OCW3
A total of 56 bytes need to be written,
and its port is only
0x20,0x21
0xa0,0xa1
four ports, these ports are also one byte, how to write these 56 bytes into these four ports?
look at the document carefully, there are strict sequence requirements on the operation, you can do two addresses to operate multiple command words, such as writing odd addresses, you can write ICW2,ICW3,ICW4,OCW sequentially also has strict address and data bit requirements, according to the document requirements to write parity two addresses, the chip can identify what command words you are sending. The four ports are two cascaded, and an 8259A has only one address line, that is, two ports.