PC/370 virtual machine

PC/370 Virtual Machine is a software package containing an IBM 370 cross assembler, linkage editor, and 370 emulator for use by students and programmers on any MS-DOS compatible PC such as the IBM PC, XT, or AT with 128K of memory. The software was originally developed in 1981 for CP/M-80 Z80 systems with 64K. (1) The cross assembler translates standard IBM 370 assembler into 370 relocatable object code. The linkage editor combines multiple 370 relocatable object modules into an executable load module file which dynamically loads the emulator at execution time. The emulator executes the standard 370 instruction set plus the packed decimal instruction set. In addition, the emulator supports extended architecture instructions, random and sequential file I/O, interactive debug, plus the extended instructions defined in ASSIST. (2) In 1985, the package was converted from Z80 macro assembler to 8086 macro assembler. This paper describes the conversion process and gives some benchmark data comparing performance of the original Z80 version and the 8086 version.