JPH02734B

A multiprocessing (MP) method is described for executing on plural CPUs of the MP a uniprocessor system (UPS) program not written to run on a MP system. Separate copies of the UPS are provided in the shared main storage (MS) of the MP. A hypervisor type of control program (called a partitioned multiprocessing system, PMP) uses the MP method to enable simultaneous execution of the plural copies of a UPS on different CPUs of the MP as UPS guest virtual machines. PMP can dedicate any CPU to the sole execution of a particular copy of UPS. The copies of the UPS run on the different CPUs independently of each other, but they may share I/O devices. PMP may run with a virtual machine (VM) type of job entry and task dispatching control-programming system designed to operate on CPUs having 370-XA architecture and to use emulation on the CPUs to permit a UPS designed for the same or another architecture (e.g. S/360 or S/370) to execute on the 370-XA CPUs as a UPS guest by using an emulation instruction (e g. start interpretive execution, SIE). Efficient direct I/O handling for the executing UPS copies (i.e. UPS guests) requires the MS boundary of each UPS to be located at a different 2 byte absolute address, so that the I/O processor can easily translate channel program and I/O data addresses used by each UPS to the actual absolute MS addresses of the MP, n being the number of bits in the effective address used by the UPS. Zone parameters are derived from the 2 boundary addresses for the respective guests. This channel translation does not require any translation tables and can avoid a MS access for each translation. A CPU may use segment and page tables to translate UPS addresses for any UPS guest's CPU requests.