Browse Prior Art Database

Subsystem Control Block Immediate Commands for the Micro Channel

IP.com Disclosure Number: IPCOM000121584D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 79K

Publishing Venue

IBM

Related People

Bonevento, FM: AUTHOR [+6]

Abstract

This article describes a technique for use in a personal computer system which utilizes registers for multiple purposes, thereby reducing the number of command registers in the MICRO CHANNEL* interface.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Subsystem Control Block Immediate Commands for the Micro Channel

      This article describes a technique for use in a personal
computer system which utilizes registers for multiple purposes,
thereby reducing the number of command registers in the MICRO
CHANNEL* interface.

      In the technique disclosed herein mechanism is defined within
the Subsystem Control Block (SCB) architecture which provides a
command format that allows for command execution without requiring
additional storage fetches or additional I/O address space.  Separate
attention types are provided in the Attention Port which allow the
subsystem to treat the 32-bit value in the Command Port as the
command instead of a storage address.  The format of the 32-bit
command is called Immediate Command Format and is defined as shown in
the drawing.
      IC Bits 31-16 - Reserved
      IC Bit 15 - Interrupt when Command completes
If bit 15 = 1, interrupt after the Immediate Command has completed
and report status in the Interrupt Status Port (ISP).  If bit 15 = 0,
do not interrupt on completion of the Immediate Command, unless an
error occurred.  Some commands ignore this specification.
      IC Bit 14 - Enable/Disable Interrupting
If bit 14 = 1, then interrupts are enabled to the system for the
specified device.  If bit 14 = 0, then interrupts are disabled to the
system for the specified device.
      IC Bits 13, 12 - Command Options Bits
These bits allow the modification of the command field. Currently
used only by the Reset Device Command.
      IC Bits 11 ---> 8 - Interrupt Count
This field specified the count for the interru...