CPU replacement on legacy test systems [for complex avionics]

This paper presents a solution to the obsolescence of the essential computing element of an automatic test system. The specific test system cited is used in production and return-to-service testing of complex avionics for commercial transport airplanes. To facilitate testing of the complex avionics used in these airplanes, the company developed an automated test system (ATS) that is currently used by our factory service centers and our airline customers. The HPATS/1000 product line was chosen as a core test system. The resulting ATS was designated the Boeing ATS-182. The ATS-182 consisted of an HP1000 F-series CPU, an HP94xx series switching system, and other rack mounted instruments. In the mid 1990's, after fifteen years of service, component obsolescence in these systems became a problem. In particular, the HP1000 CPU had become increasingly unsupportable. The outdated HP1000 architecture) was also an obstacle to improvements we wanted to make in test software tools and processes. In addition, new, more sophisticated avionics were being developed that required more computer capability in the test system than what the HP1000 could provide. Thus was born the ATS-182a CPU replacement project in which we replaced the HP1000 with a Sun Microsystems ULTRA 30 SPARC workstation. This paper will discuss the essential challenges in the system hardware and software modifications that were addressed by this project. System hardware challenges included the CPU change; replacement of a legacy electromechanical operator control panel; and substitution of a parallel digital instrument interfaces with IEEE 488 to parallel conversion devices. Our software challenges included rehosting the HP BASIC 1000D interpreter and the Boeing ARINC 616 ATLAS compiler as well as the original FORTRAN based test environment instrument driver libraries.