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Programming Considerations in Porting to Microsoft XENIX System V/386 XENIX System V/386 is the Microsoft version of the UNIX Operating System ported to the Intel 386 microprocessor. The product, which […]

Microcomputer versions of UNIX are attempting to ease the programmer's job, as the original UNIX is not easy to use. Genix is just one example, and features a C compiler, a PASCAL compiler, and assembler and debugging utilities designed for use with National Semiconductor's NS16032 microcomputer. The operating system also features dual address spaces, a demand-paged virtual-memory scheme, and a replacement algorithm that determines how to make room for new pages.

National Semiconductor Corp.'s NS16082 XMOS chip is designed for use in NS1600-based systems where increased memory is required. It provides high-speed hardware assistance for implementation of demand paging. The chip is a memory-management unit that performs memory mapping and protection, while also providing on-chip facilities for debugging and implementation of virtual machines, when driven as a slave processor by the NS16032 CPU. The NS16032 allows system designers to take advantage of the sixteen-megabyte memory space available with the latest architectures without greatly increasing the price of end systems. It provides for sophisticated capabilities such as virtual memory, software protection, and built-in debugging without the need for additional main memory. Block diagrams and a photograph of the NS16082 are included.