Browse Prior Art Database

Providing Memory Refresh During a COP Halt Command

IP.com Disclosure Number: IPCOM000120636D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Dhawan, S: AUTHOR [+4]

Abstract

Disclosed is a method to refresh dynamic memory containing control information, after the I/O Channel Controller (IOCC) is halted by the COP Halt command so as to enable the IOCC to restart cleanly.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 98% of the total text.

Providing Memory Refresh During a COP Halt Command

      Disclosed is a method to refresh dynamic memory
containing control information, after the I/O Channel Controller
(IOCC) is halted by the COP Halt command so as to enable the IOCC to
restart cleanly.

      The IOCC generates the Micro Channel*.  It uses dynamic memory
to store control information for Direct Memory Access (DMA)
operations.  The COP Halt command is used to stop execution of the
processor for diagnostics.  After diagnostics, the COP restarts the
processor.  With refresh being provided during diagnostics, the
processor can continue from where it was halted, rather than
restarting from the beginning.

      When the IOCC receives the COP Halt command, it requests the
use of the Micro Channel by the driving the '-PREEMPT' line active on
the Micro Channel.  The IOCC then goes into an arbitration wait
state.  This holds all devices on the Micro Channel.  Refresh cycles
occur during the extended arbitration state.  When the COP Halt
command completes, the arbitration cycle completes, and the processor
is restarted from where it was halted.

      This provides system diagnostics with the I/O bus halt being
nondestructive, hence significantly improving diagnostic performance.
All DMA operations can continue without a restart.  It reduces
diagnostics code and provides diagnostic capability that may not have
been possible if it had become necessary to restart all I/O
operations.
*  Trade...