System/370 Capability in a Desktop Computer

A desktop computer with System/370 capability was produced by enhancing the IBM Personal Computer XT with additional hardware and developing software that provides a compatible interface. The computer, the IBM Personal Computer XT/370, and this software allow users to run most System/370 Conversational Monitor System application programs unaltered in a desk-top environment. The evolution of the development and details of the function of the hardware and software are described. L arge investments have been made by many computer users in System/370 software and in the skills needed to develop, maintain, and use such software. IBM'S recently announced Personal Computer X T ~ O (PC XTWO) running Virtual Machine/ Personal Computer (VMIPC) software is a big step towards using System/370 software in microprocessor based desktop computing systems. VM/PC is a single-user control program which provides an interface that is compatible with the Conversational Monitor System (CMS) and capable of supporting most existing CMS application programs. The application programs execute on the small, relatively inexpensive desktop computer just as they would on a larger System/370 mainframe and include user programs, editors, document composers, language processors, etc. The PC XTWO was produced by enhancing the hardware of the IBM Personal Computer XT (PC XT) with three cards: a communications card, a 5 12K memory card, and a coprocessor card. Together these cards provide the System/370 instruction execution capability along with the ability to connect to System/ 370 host systems. VM/PC not only provides the necessary interface to support CMS programs, but also provides a means of coupling its CMS environment with a CMS environment running in a host processor and the ability to transfer files between the IBM