System for coordinating execution of multiple concurrent channel programs without host processor involvement using suspend and resume commands to control data transfer between I/O devices

摘要

Coupling execution of channel programs without central processing unit supervision controls data transfer between input/output devices through a main storage of a data processing system. In one embodiment, channel programs to be coupled are generated by a program running on a data processing system central processing unit. The channel program on the input subchannel includes channel commands referencing the output subchannel and operating to cause resumption of the output subchannel. The channel program on the output subchannel includes suspend channel commands directed to itself which correspond to the resume channel commands in the channel program on the input subchannel. In alternative embodiments values in channel commands can change values in, or reference, control blocks to effect execution of other channel programs.