IBM System/360 architecture: Difference between revisions

Revision as of 09:14, 5 February 2023

Revision as of 21:34, 5 February 2023

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===I/O instructions===

The S/360 has four{{sfn|S360|loc=[http://bitsavers.org/pdf/ibm/360/princOps/A22-6821-7_360PrincOpsDec67.pdf#page=105 Control of Input/Output Devices]|pp=93-98}} I/O instructions: Start I/O (SIO), Test I/O (TIO), Halt I/O (HIO) and Test Channel (TCH). All four are are privileged and thus will cause a privileged operation program interruption if used in problem state. The B₁ (base) and D₁ (displacement) fields are used to calculate the cuu (channel and device number); bits 8-15 of the instructions are unused and should be zero for compatibility with the S/370.

====Start I/O (SIO)====