Implementation of a movement paradigm using the Commodore 64 microcomputer

Implementation of an alternating movement paradigm for monkeys was achieved using an inexpensive but versatile microcomputer, the Commodore 64. During task performance, the computer monitors one of three user selectable input signals (e.g. joint position) and continuously displays this signal as a moving cursor on a video monitor along with a user positioned target box. Other user defined parameters include in-target holding time and reinforcement ratio. The system also provides two sound cues to signal entry of the cursor into the target box and successful completion of a trial. Extensive use is made of the computer's intrinsic hardware features for implementation of movement paradigm functions. Use of external components is limited to digitizing and interface hardware. A two part software package consisting of a BASIC and a machine language program performs all task and hardware related functions. Acquisition and display of analog input signals, display of target positions, and delivery of auditory cues and applesauce rewards are all controlled by the machine language program. All user defined parameters are specified from the BASIC menu program. The specific programs described in this paper should be applicable to the control of tasks requiring alternation of a behavioral parameter between two target zones.