This register has two different functions depending on bit7 of the data written to this register.
=== PPI Control with Bit7=0 ===
Otherwise, if Bit 7 is "0" then the register is used to set or clear a single bit in Port C:
Bit 0 B New value for the specified bit (0=Clear, 1=Set)
Bit 1-3 N0,N1,N2 Specifies the number of a bit (0-7) in Port C
Bit 4-6 - Not Used
Bit 7 SF Must be "0" in this case
[[File:Intel 8255A - BSR control word format.jpg]]
=== PPI Control with Bit7=1 ===
[[File:Intel 8255A - IO modes control word format.jpg]]
=== PPI Control with Bit7=0 ===
Otherwise, if Bit 7 is "0" then the register is used to set or clear a single bit in Port C:
Bit 0 B New value for the specified bit (0=Clear, 1=Set)
Bit 1-3 N0,N1,N2 Specifies the number of a bit (0-7) in Port C
Bit 4-6 - Not Used
Bit 7 SF Must be "0" in this case
[[File:Intel 8255A - BSR control word format.jpg]]
== Programming Examples ==