Pregnancy registry system. A model database system for collection, dissemination, and analysis of data in multiple international prenatal drug exposure registries

Abstract

One of the most common types of architecture has been based on the classical Von Neumann structure extended with features to support high-level languages or operating system execution. The most frequent additions are a stack for subroutine calls, virtual memory support, multitasking support through special instructions, addressing modes to facilitate array and record accessing, user/supervisor modes, and a richer variety of data types. To accommodate all these functions, these machines implement a large number of instructions, typically 200–300. Because of their complexity, the instructions of this type of system require several machine cycles for their execution, which is why these types of machine are called complex instruction set computers. For applications that do not require maximum performance, for single-user environments or for multiuser environments that do not require a high level of security or integrity, this approach is convenient and sufficient. The chapter presents four commercial systems that require the state of the art for this type of architecture: (1) Motorola MC68020, (2) Motorola MC68030, (3) National semiconductor NS32000 series, and (4) Zilog Z80000.