Electronic random-access slide projector controller

Claim 1

An electronic random-access slide projector controller comprising multi two-input exclusive-OR gates having first inputs adapted to be supplied with an input signal encoded in binary coded decimal and representing the desired number of a slide to be selected for viewing in a random-access slide projector, means for applying a START command signal to the slide projector controller for initiating operation thereof, a clock generator for producing clock pulses in response to the START command signal, said clock generator maintained in an inactive state prior to the START command signal, control logic means having a first input connected to an output of said START command signal applying means and having a first output connected to an input of said clock generator for applying a HOLD signal thereto which maintains said clock generator in the inactive state in which no clock pulses are produced at the output thereof, first and second counter means each having a reset input connected to a second output of said control logic means for resetting said first and second counter means to zero in response to the START command signal, said first and second counter means each also having a trigger input connected to an output of said clock generator for counting the clock pulses after the counter means have been reset to zero, the end of the START command signal removing the HOLD signal from said clock generator so as to cause the clock pulses to be supplied to said first and second counter means, said first counter means adapted to count the clock pulses in base 10, said second counter means adapted to count the clock pulses in a base other than 10 to provide compatibility with a code matrix used to specify a slide number for location identification of the slides stored in the projector slide tray, outputs of said first counter means connected to second inputs of said multi two-input exclusive-OR gates coincidence between the signals applied to the first and second inputs of said multi two-input exclusive-OR gates causing outputs thereof to produce a signal applied to a second input of said control logic means which causes the first output thereof to again apply the HOLD signal to said clock generator so as to stop the counting operation of said first and second counter means, the count stored in said second counter means at the reapplication of the HOLD signal to said clock generator being the base other-than-ten equivalent of the desired decimal slide number, first one-of-base-other-than-10 decoder means having inputs connected to first outputs of said second counter means for providing a signal at only one particular output of a plurality of outputs of said first decoder means which identifies the row in the code matrix specifying the desired slide number wherein the plurality of outputs is equal in number to the base otherthan-10, second one-of-base-other-than-10 decoder means having inputs connected to second outputs of said second counter means for providing a signal at only one particular output of a like plurality of outputs of said second decoder means which identifies the column in the code matrix specifying the desired slide number, first and second means each having a like plurality of inputs connected to the outputs of said first and second decoder means, respectively, for interfacing said first and second decoder means with the projector mechanism which searches for the particular row and column in the code matrix identified by the counts stored in said first and second counter means, and a third output of said control logic means connected to the projector for supplying an ACTUATE signal thereto at the time the HOLD signal is reapplied to said clock generator to initiate the slide search operation of the projector.