In some of these modes, port C is used as a control/status port for port A or B. It can be used to confirm when data transfer may take place, and reflect any other flags. The 8255 PPI is therefore supplied with the added option for the user to set or reset any individual bits in port C.
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=== Mode 0 – Simple Input/output mode ===
[[File:8255 - mode-0.png]]
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=== Mode 1 – Strobed Input/output or Handshake mode ===
[[File:8255 - mode-1.png]]
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=== Mode 2 – Bidirectional Mode ===
[[File:8255 - mode-2.png]]
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=== Port pins summary ===