Logical diagram in hard copy relating to the computer CSIRAC. Large handrawn diagram on fine kraft paper (section missing) of the logical structure of CSIRAC.

A logical diagram is a detailed graphical representation of one of the principal parts of CSIRAC. Each functional component is represented by a symbol. The diagram shows the connections between these components. In CSIRAC, each functional component consisted of several physical components such as vacuum tubes, resistors and capacitors. Logical diagrams are used to understand the functioning of a circuit.

The diagram was originally displayed in the Computation Laboratory. It was possibly used to describe the structure of the computer to students of programming courses. It is a more detailed version of a similar diagram in the course notes provided for programming courses in the late 1950s. The diagram for many years was taped to a cardboard backing sheet. It may be important since it gives more detail of the overall structure than other diagrams.
(The diagram was retained by Peter Thorne when the Computation Laboratory was closed down and occasionally used in Courses on Computer Design during the 1970-80s.)

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