This paper contains the technical specifications, schematic diagrams, and program printout for a computer software package for the development and administration of diagnostic tests. The second version of the Diagnostic Testing Package DX consists of a PASCAL-based set of modules located in two main programs: (1) EDITTEST creates, modifies, and reviews the test materials which are to appear on screen; and (2) RUNTEST administers, manages, and scores the real-time testing session. EDITTEST creates two files for each test: (1) "filename" Q.TEXT, a test file containing registers for each test item; and (2) "filename," a datafile containing the test text. RUNTEST opens the EDITTEST files for input and an output file, "studentname." TEXT, which summarizes a student's test performance. This last file follows the format requirements of STATPAK, a microcomputer statistical package which is being adapted for a third main program for the DX package. (BS)