For what it is worth to note...The port C pins of the 82C55 that are set to output can be individually set and cleared via an instruction byte written to the 8255.

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Now I need to ask you you really want to use a relic chip like the 82c55 in a new design. I would caution against doing this if the product you are building is expected to any sort of life expantcy at all.
Michael Karas