Browse Prior Art Database

Use of Ready And Data Valid Control Signals to Freeze Data Transfers at Severe Error Conditions

IP.com Disclosure Number: IPCOM000120493D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Bailey, RN: AUTHOR [+3]

Abstract

Disclosed is a method which uses data transfer synchronization control signals to freeze the transfer control circuits when a severe transfer error occurs. This preserves the state of the transfer at the time of the error so that it can be scanned out and the problem diagnosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 80% of the total text.

Use of Ready And Data Valid Control Signals to Freeze Data Transfers
at Severe Error Conditions

      Disclosed is a method which uses data transfer synchronization
control signals to freeze the transfer control circuits when a severe
transfer error occurs.  This preserves the state of the transfer at
the time of the error so that it can be scanned out and the problem
diagnosed.

      In a multi-level DMA configuration, where data passes through
several buffers on its way to/from main storage, the problem of
determining the source of transfer errors can be complex.  This
problem was overcome in the Common Channel/ Serial Link Adapter
design by using two data transfer synchronization signals, Ready and
Data Valid to freeze the transfer controllers at the point of error.
Once the state of the machine has been held, the LSSD latches can be
scanned and the failure diagnosed.

      The Common Channel interfaces the Serial Link Adapter over a
DMA data bus.  When the Serial Link Adapter transmits data, a request
is made to the Common Channel.  To begin the transfer of data to the
Serial Link Adapter the Common Channel activates the Data Valid
signal if the data transfer is correct, the Serial Link Adapter
activates the Ready signal which causes the Common Channel to
continue to the next transfer. If an error was detected by the Serial
Link Adapter, it would enter an error state and not activate the
Ready line causing the Common Channel to freeze, since it is wait...