This is perhaps not exactly what you look for but, as a partial answer, the Advanced Search feature of the directory of open access journals (DOAJ) lets you filter the open access journals by subject AND by publication fee. Unfortunately, you cannot infer from the DOAJ data whether these journals are on JCR.
In particular, the DOAJ search results for open access journals in Computer Science with zero publication charges are at this URL.
In principle, as a next step one could compare (by hand or perhaps using some software) the list resulting from the DOAJ search with the list from JCR for (a given branch of) computer science or search in JCR (e.g. in the list of full journal titles) for specific journal names.
Also, the DOAJ listing includes links to home pages of journals and often data about the journal impact factor (if any) or JCR listing are available at these home pages.
To give a specific example resulting from a quick attempt to compare the lists, the Journal of Artificial Intelligence Research is open access with zero publication charges and has a 2013 IF of 0.904.