Browse Prior Art Database

Half-duplex Wrap Test, Walking-reset Error-forcing Techniques

IP.com Disclosure Number: IPCOM000120829D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 7 page(s) / 260K

Publishing Venue

IBM

Related People

Bergey Jr, AL: AUTHOR

Abstract

These two inventions are a method of testing a half-duplex interface with full-duplex wrap techniques, and a method of diagnostically exercising check logic with a "walking reset". WRAP TEST FOR HALF-DUPLEX INTERFACE

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Half-duplex Wrap Test, Walking-reset Error-forcing Techniques

      These two inventions are a method of testing a
half-duplex interface with full-duplex wrap techniques, and a method
of diagnostically exercising check logic with a "walking reset".
WRAP TEST FOR HALF-DUPLEX INTERFACE

      WRAP TEST OVERVIEW:
This invention allows a half-duplex data transfer interface that has
limited full-duplex control facilities to be wrapped as if the data
transfer interface were full-duplex.

      The standard way to self-test a computer interface is to wrap
the outputs around to the inputs, so that the interface thinks that
it is talking to the outside world, but it is actually talking to
itself.

      Wrapping is straightforward when the interface is full-duplex
(that is, it can simultaneously transmit and receive independent
streams of information).  It is generally not possible when the
interface is half-duplex (that is, it can transmit or receive data,
but only one at a time).

      This invention is implemented in a control unit which talks to
a channel, as shown in Fig. 1, with the following components:
1. Microprocessor
2. Transmit Buffer
3. Receive Buffer
4. Data Transfer Facility
5. Data to or from the rest of the control unit
6. Data to channel
7. Data from channel
8. Diagnostic wrap

      This design has the following characteristics:
1.  The design distinguishes between facilities for passing control
information, which are full-duplex, and facilities for passing bulk
data, which are half-duplex.
2.  Control information is transmitted with the Transmit Buffer.
This facility is independent of the other parts of the serial
interface, except that control information cannot be transmitted at
the same time as automatic data transfer information.

      3.  Control information is received by the Receive Buffer. Any
incoming information except certain specific data transfer frames is
placed into the receive buffer.

      4   The Transmit Buffer and Receive Buffer form a full-duplex
facility for transmitting and receiving control information.

      5.  The Data Transfer mechanism controls actual bulk data
transfer.  In order to meet performance requirements, controls for
the transmission and reception of frames associated with data
transfer are built into the hardware of the Data Transfer mechanism.
The Data Transfer mechanism is set up by microcode, but once the data
transfer begins, the hardware is completely automatic until the
transfer ends.

      6.  During WRITE data transfer, the Data Transfer mechanism
automatically generates and transmits "Data Request" frames.  It
monitors incoming frames, and when an incoming frame is recognized to
be a "Data" or "Command Update" frame, it processes the frame
automatically.  Frames other that Data or Command Update are placed
into the Receive Buffer, and are processed by microcode.

      7.  During READ data transfer, the Data Transfer mecha...