The IBM Virtual Machine Communication Facility (VMCF) is a feature of the VM/370

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

introduced in Release 3 in 1976. It "provides a method of communication and data transfer between

virtual machine In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized har ...

s operating under the same VM/370 system." VMCF uses

paravirtualization In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface. The intent o ...

through the ''diagnose'' instruction VMCF SEND function to send data, in blocks of up to 2048 bytes, from one virtual machine to another. The receiving virtual machine accesses the data thru the diagnose RECEIVE function. It provides a simpler interface and greater performance than the prior use of virtual channel-to-channel adapters for the same purpose.

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