Electrical testing apparatus and methods

A system for generating test data for testing any one of a plurality of logic circuits, comprising

• a store storing, for each of the basic logic circuit types, data in the form of a respective list of logic states, each logic state identifying one or more particular terminals of the logic circuit to which specified data inputs are to be applied and one or more particular terminals at which specified data outputs are to be produced if the logic circuit is operating correctly,
• an array of discrete contact means,
• means mounting the contact means in predetermined physical relationship with each other whereby when the array and a particular logic circuit under test are brought into juxtaposition each discrete contact means makes contact with at least one particular terminal of the logic circuit in dependence on the particular basic type of the logic circuit,
• means storing, for each particular logic circuit to be tested, connection data which specifies for each particular one of the discrete contact means the identity of the corresponding terminal of the logic circuit and, in addition, the identity of any other terminal of that logic circuit which is also connected to the same discrete contact means by an external connection to that logic circuit,
• control means operative in response to a particular logic circuit to be tested to read out each logic state of the stored list of logic states corresponding to that basic logic circuit type and to compare each such logic state with the connection data whereby, unless inhibited for any such logic state, to identify the discrete contact means corresponding to the particular terminals specified by that logic state and the data inputs and outputs to be applied to, or produced from, those contact means as specified by that logic state,
• inhibiting means operative to inhibit the control means when the connection data indicates that two or more terminals of the logic circuit under test are interconnected by an external connection in a manner conflicting with the requirement of a particular logic state, and
• output means responsive to the said discrete contact means and the data inputs and outputs as identified by the control means to generate the said test data.