International Business Machines Corporation

James J Pertzborn

David Otto Lewis

Roy L Hoffman

Thomas S Robinson

Nyles N Heise

Istvan S Kiss

Control apparatus is responsive to CPU I/O commands for initiating chained I/O data transfers to cause virtual address translation (VAT) apparatus to translate a first virtual address to be used in the chained data transfer operation and load the translated (resolved) address in an I/O resolved address register reserved (unique) to the commanded I/O device connected to a shared I/O control unit and to repeat such an operation for each I/O device commanded by the CPU to do a data transfer and responsive to a command from the shared control unit indicating that one of the commanded I/O devices is ready for data transfer to become nonresponsive to further CPU I/O commands and cause the VAT to resolve a succession of virtual addresses for the data transfer and to load the resolved addresses into I/O resolved address registers shared for use by all of I/O devices whereby a data transfer operation can commence using the resolved address in the register unique to the I/O device which is first ready for data transfer and thereafter continue with data transfers using resolved addresses from the registers shared by all of the I/O devices but captured for use by the I/O device first ready for data transfer. Upon the data transfers being completed for that I/O device, the VAT resolves a succession of virtual addresses and loads them into the shared registers for use during data transfers by the next ready I/O device in response to a command from the shared I/O control unit.

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Rochester, MN, United States of America

James J Pertzborn