I am almost sure that you are seeing a typographucal mistake on the Harris data sheet.

The WR pin on a 82C55 is for sure a low active pin.

As a matter of fact...please look at the pinning diagrams on the first page of this Intersil data sheet and you will see that it shows the WR pin on the DIP-40 pinoutwhthout the overbar. However on the symbols for the CLCC anf PLCC-44 pinouts the WR is shown with the overbar.


This is a good time to point out that you should never depend completely on the graphical pictures of the pinning diagrams in data sheets for understanding the functionality of how chip pins work. You need to also to check the pins description section or table.

Michael Karas