1A Processor: Technology and Physical Design

1A technology is a standard set of devices, apparatus, and design tools which are used not only to design the 1A Processor and No. 4 ESS system, but also new switching systems such as No. 3 ESS1 and additions to present systems such as the remreed network for No. 1 ESS. 2 It has been made a broad and flexible technology applicable to an entire new generation of telephone switching equipment. The hardware design requirements of these "new-generation" switching systems differ in many important ways from the switching hardware typified in the No. 1 ESS system. 3 The advent of silicon and hybrid integrated circuits in the mid-1960s provided an opportunity for dramatic miniaturization in hardware. The first-level package in these new switching systems is often a silicon integrated-circuit chip about 50 thousandths of an inch square. Such a chip often contains more circuit 207 components than a 4- by 7-inch plug-in package in previous systems. The influence of miniaturization is characterized at every level of packaging by the reduced size and increased density of required interconnections. Interconnections are also affected by another continuing trend, that of upgrading the performance of new switching equipment. Increased machine speeds and faster pulse rise times are required to provide more throughput and improved service. As the speed increases, so does the sensitivity to noise and transmission losses. As a consequence, stringent electrical requirements are imposed on the interconnections in faster machines such as the 1A Processor.