Abstract

In an educational television system, a constructed answer system is based on the use of code pulses that are repeated cyclically during their concealed transmission within a television video waveform. Indicia, e.g., letters of a word or formula, are preloaded into a store in the form of binary code as an output from a punched tape reader or an encoder for a keyboard. The encoder is reset following each transfer of encoded indicia to the store which is indexed by a shift register to render responsive successive columns of flip-flops in a matrixed arrangement. The store includes a column of AND gates to store a permanent "recycle code". The reading of the store is clocked by modified sync pulses applied by a shift register to a matrix arrangement of interconnected AND gates that are also connected to the output of the flip-flops. The readout of the store is repeated cyclically by a logic register that compares the number of encoded indicia in the store with the number of encoded indicia read from the store. Further circuitry, using AND gates, is responsive to a student keyboard to compare the student response with the decoded indicia signals to determine a correct response.

Other References

• Featherston and Luper, "Interactive Instructional System," IBM Tech. Disclosure Bulletin, vol. 14, No. 10, pp. 3125-3126, March 1972