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Modifications for Slotted Ring Access Method

IP.com Disclosure Number: IPCOM000102775D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 63K

Publishing Venue

IBM

Related People

Bunkofske, RC: AUTHOR [+6]

Abstract

Two modifications of slotted ring access methods are described. They are (1) implementing variable slot sizes to accommodate larger data lengths, and (2) changing an addressing scheme to permit more stations to be added to a ring.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Modifications for Slotted Ring Access Method

      Two modifications of slotted ring access methods are described.
They are (1) implementing variable slot sizes to accommodate larger
data lengths, and (2) changing an addressing scheme to permit more
stations to be added to a ring.

      Conventionally, a length of slots in a slotted ring is of fixed
length.  The length of each slot is 37 bits.  The 37 bits include
five control bits.  In addition to the five control bits, two more
control bits are added called LA. Setting of control bit L determines
how data length is calculated.  Control bit A indicates whether
simple addressing scheme or an extended addressing scheme is used.

      With variable data length slots, however, the data length in
each slot need not be fixed.  With the addition of one or more bytes
to each slot, it is possible to compute the data length per slot.
The variable length control bit (L) determines the way the length of
data bytes is computed. If the L bit is a zero, the value of the
eight bits (xxxx xxxx) provides the length of data bytes.  On the
other hand, if the L bit is one, the bit pattern is 1111 xxxx .....
xxxx xxxx.  Here 1111 indicates the length of extra bytes which are
used for calculating the length of data bytes.

      For example, in the bit pattern 0010 0000 0000 0000 0000 1111,
0010 states that 2 more bytes are used for calculating the data
length.  So, the bit pattern for calculating length is 0000 0000 00...