Browse Prior Art Database

Transparent Transmission Mechanism

IP.com Disclosure Number: IPCOM000104638D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR [+2]

Abstract

In a communication subsystem, it is often desirable to utilize a transmission code set that has error detection and/or correction properties. This implies that the transmission code set will differ from the code utilized internally to the processor complex. Thus, a facility is required to perform code conversion between the internal code and the transmission code at both the transmitter and receiver. For performance reasons this facility is normally implemented in hardware.

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

Transparent Transmission Mechanism

      In a communication subsystem, it is often desirable to utilize
a transmission code set that has error detection and/or correction
properties.  This implies that the transmission code set will differ
from the code utilized internally to the processor complex.  Thus, a
facility is required to perform code conversion between the internal
code and the transmission code at both the transmitter and receiver.
For performance reasons this facility is normally implemented in
hardware.

      A transparent mode data format is disclosed which permits the
transmission of link character sequences and delimiters which are
outside the scope of the architecture (native mode).  This mode
permits invalid link characters, error frames and incorrect cyclic
redundancy checks (CRCs) to be transferred to test error detection
capability of the receiver.

      In a transparent mode, an entire frame will be transmitted from
main storage.  That is, the Start of Frame (SOF) delimiter, Cyclic
Redundancy Check (CRC) and End of Frame (EOF) delimiter ten bit link
transmission code characters must be supplied in main storage.  The
data will then be stored in the ten bit link image with three
characters per word (32 bits) as shown in the accompanying figure.
Link data characters will then be fetched from main storage and
passed directly to the link serialization facility bypassing the
automatic conversion mechanisms of the channel hardware.

In order to accomplish this transparent mode certain rules must be
established:

o   Hardware Responsibilities:

    -   the link disparity will be minus prior to transmission of the
        first link character  from the "transparent" buffer; and
    -   the channel hardware will guarantee that correct disparity is
        maintained on entry and exit of the transparent mode
        transaction.

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