VIRTUAL STORAGE DATA PROCESSING APPARATUS INCLUDING I/O

摘要

In virtual storage data processing apparatus including real main storage, 10 a virtual address translation unit VAT 15 and a common I/O control unit 110 serving plural I/O devices, 150 the virtual address translation unit includes a resolved address register for each I/O device, a pool of resolved address registers and control logic responsive to a device specific CPU I/O command for initiating chaines I/O data transfers to cause the VAT apparatus to translate a first virtual address to be used in the chained data transfer operation and load the translated (resolved) address the appropriate resolved address register 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 resolved address registers of the pool 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.