Browse Prior Art Database

Storing of Subchannel Type with Interruption Information

IP.com Disclosure Number: IPCOM000109036D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Meritt, AS: AUTHOR

Abstract

As the ESA/390* I/O architecture evolves, a new subchannel type beyond I/O subchannels has been created, and, in the future, additional types may be created. These are all part of the same subchannel "name space", i.e., are all within the 64K subchannels addressable by the 16-bit subchannel number. They are associated with different facilities, and may even require different instructions to initiate operations or retrieve completion information. However, they all signal completion with an I/O interrupt for which there is only 1 interruption handler. This describes a mechanism by which the interruption handler can more easily handle interruptions in this environment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Storing of Subchannel Type with Interruption Information

       As the ESA/390* I/O architecture evolves, a new
subchannel type beyond I/O subchannels has been created, and, in the
future, additional types may be created.  These are all part of the
same subchannel "name space", i.e., are all within the 64K
subchannels addressable by the 16-bit subchannel number.  They are
associated with different facilities, and may even require different
instructions to initiate operations or retrieve completion
information.  However, they all signal completion with an I/O
interrupt for which there is only 1 interruption handler.  This
describes a mechanism by which the interruption handler can more
easily handle interruptions in this environment.

      Without any changes from the base ESA/390 architecture, the I/O
interruption handler would have to issue a "Store Subchannel" (STSCH)
instruction to determine the subchannel type; after that, it could
then know how to serialize, how to interpret the I/O interruption
parameter (which was originally architected for 370-XA and was
intended to speed up software processing of interrupts), and what
control block structures looked like.  The different subchannel types
represent different facilities generating I/O interrupts; since they
are different facilities, they may very well require different
software control block structures.  This makes the interruption
parameter context-sensitive, so it cannot be utilized until after
deter...