This paper explores the idea that the cognitive state during problem solving diagrams is bi-modal, one of whose components is the traditional predicate-symbolic representation composed of relations between entities in the domain of interest, while a second component is an internal diagrammatic representation. In parallel with the operators in the symbolic representation that are based on symbol matching and inferencing, there is a set of operators in the diagrammatic component that apply perceptions to the elements of the diagram to generate information. In addition there is a set of diagram construction operations that may modify the diagram by adding, deleting and modifying the diagrammatic elements, in the service of problem solving goals. We describe the design of the diagrammatic component of the architecture, and show how the symbolic and diagrammatic modes collaborate in the solution of a problem. We end the paper with a view of the cognitive state as multi-modal, in consonance with our own phenomenal sense of experiencing the world in multiple modalities and using these senses in solving problems.