The first generation of APATS, the Contact Test Set, was fielded in the late 1980s.
In the 1990s, the Product Director for Test, Measurement, and Diagnostic Equipment (PD TMDE) developed the next generation of APATS. The Soldier Portable On-System Repair Tool (SPORT) gave the maintainer the ability to diagnose and repair various weapon systems using electronic technical manuals (ETMs) on a controller diagnostic aid.
In the late 1990s, SPORT was obsolete, and PD TMDE fielded the next generation of APATS: the Maintenance Support Device (MSD).
The MSD was identified as the Army's preferred APATS and ETM reader.
In December 2011, the MSD version 3 was fielded as a smaller, more capable APATS netbook.
These innovative changes within APATS have kept pace with the Army's emerging requirements and have supported weapons system readiness.
Unlike APATS, OPATS have no single source of procurement and management.