Note: Descriptions are shown in the official language in which they were submitted.
-
1056948
BACKGROUND OF THE INVENTION
This application is a divisional of Canadian Patent Appli-
catio~ Serial No. 228,005 filed May 29, 1975
The invention relates generally to the field of
magnetic bu~ble technology ~MBT) and, more particularly, to
means forpropasatingor transmitting magnetic bubbles, especially
in field-accessèd mutually exclusive propagation channels.
; 5 MBT involves the creation and manipulation of magnetic
bubbles in specially prepared magnetic materials. The word
~bubble~, used throughout this text is intended to encompass
any single-walled magnetic domain, defined as a domain having an
outer boundary which closes on itself. The application of a
static, uniform magnetic bias field orthogonal to a sheet of
magnetic material having suitable uniaxial anisotropy causes the
normally random serpentine pattern of magnetic domains to shrin~
into isolated, short cylindrical configurations or bubbles whose
common polarity is opposite that of the bias field. The bubbles
repell each othcr and can be moved or propagated by a magnetic
field in the plane of the sheet.
Many schemes exist for propagating bubbles along pre-
determined channels. These techniques can be classed generally
as conductor-accessed and field-accessed. In conductor-accessed
propagation systems, electrically pulsed conductive loops are
. .
disposed in series over the magnetic sheet. In field-accessed
propagation systems electrical conductors are not disposed on the
magnetic sheet for propagation; instead, an overlay pattern of
ferromagnetic elements establishes a bubble propagation channel
in which a sequence of attracting poles is caused to be formed
in the presence of a continuous, uniformly rotating magnetic
drive field in the plane of the sheet.
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i~56948 ; 07-21-0253
.
A ma~or dist~nction in function between conductor-
accessed and field-accessed circuits is that several conductor-
accessed circuits can be disposed on the same sheet or ~bubble
¢hip~ and operated completely separately and exclusively from
each other whila fleld-accessed circuits on the same chip all
operate at the same time under the control of an ubiquitous
uniformly rotating, common drive field.
One attempt at providing fiela-accessed channel
.
seleotion is shown i'n U.S. Patent 3,543,2~2 to Perneski illustra-
ting several v,ariations on the familiar T-bar circuit to'which
different permutations of pulsed orthogonal drive fields are
applied.
NBT can be used in data processing because magnetio
bubbles can be pxopagated through channels, whethe'r fie'ld-
aooessod or conductor-accessed, at a precisely determined rate
^-o.that uniform data ~treams of bubbles are possl~le ln WhlCh
; th~ presence or absence of a bubble at a particular position
~ithin the Q-tream indicates a binary ~1~ or "0~. Because of -,
lts potential $or low cost, low power consumption and extremely
, 20 hi~h bit densit,y, MBT is under active consideration for us~ in '~
large scale memories of moderate speed. One of the prime aesign
elements of many memory systems utilizing field-accessed magnetic
bubbles is the provision of closed loop bubble path which'can
' b~ u8ed as a recirculating ~shift registern. Many memory arrange-
ments`of this type employ a plurality of ~minor~ loops selective- -
ly interconnectible with a ~major~ loop such that bubbles can be
tran~ferred between the ma~or and minor loops on command.
"'
3 ..
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07-21-0253
i056948
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.: ' ' , ,
The ablllty to propagate bubbles ln one or more
re¢lr¢ulatlng loops wlthout operatlng other loop~ on the same
¢hlp has until re¢ently been conrined to sy~tems employlng
conductor-accessed clrcults. Mutually excluslve ciosed loop
rleld-accessed bubble propagatlon clrcults are disclosed ln
Belglan Patent No. 821,730, by Howard H. Alken, Paul T. Balley
and Robert C. Mlnnlc~, entitled "Mutually Excluslve Magnetlc
Bubble Propagatlon Clrcults". Dlscrete mutually excluslve
`~ clrcult elements and systems composed Or them are dl6closed
ln Belglan Patent No. 821,731 by Paul T. Balley and L. John Doerr
III, entltled "Mutually Excluslve Magnetlc Bubble Propagatlon
; Clrcults Wlth Dlscrete Elementsn. Bubble paths havlng rectangu-
lar and parallelogram geometrles are dlsclosed ln Belglan Patent
No. 827,219, by Robert M. Sandrort, entltled "Mutually Excluslve
15 Parallel-Slded Bubble Clrcults"~ -
In bubble clrcult deslgn, the need orten arlses ror
controllably transrerrlng bubbles on one path to another path,
ror example,.rrom a mlnor to a ma~or loop ln a memory organlza-
tlon. One transrer technlque ln rleld-acces~ed systems 18 to
emplo~ one or more conductor 1OOPB whlch can be pulsed on com-
mand to attract bubbles on one path to an alternate path.
Another approach to bubble transrer lnvolves the use Or con-
ductors plu8 speclal rleld-accessed transrer elements. See,
ror example, Smlth et al, "Dollar Slgn Transrer rOr Magnetlc
Bubblesn
.
. 105699U3 . 07-21-0253
.
, ,' : .
tPaper No. 13.2), 1973 Intermag Gonference; U.S. Patent No. ''
3,714,639 to ~ish et al, and Nos. 3,613,058, 3,61~,054 and '
3,713,116 to Bonyhard et al; and ~osch et'al, ~1024 - bit
Bubble Memory Chip" ~aper No. 26.2), 1973 Intermag Conference.
Of courge, if conductors are lnvolved at all, the overlay
pattern becomes more difficult to implement.
Specific field-accessed transfer systems have'been '
previously described. In Michaelis et al ~Magnetic Bubb~le
Repertory Dialer ~lemory~ IEEE Trans. Maq., September 1971,
p. 737, minor/ma~or ioop transfer ~gates~ are described which
can be simultaneousiy activated by reverse rotation of the arive
field. Distinct T-bar loops are joined by specially designed
transfer elements. Propagation on the ma~or and minor loops ¦
oannot be reversed without transfering bubbles. Bonyhard et al, j-
~Applications of Bubble Devices", IEEE Trans. Mag., MAG~6, 1~'
~o. 3, Sept.'1970, p. 447 ~Fig. 1), al50 discuises "reverse
propagation transferU. The Bonyhard article also describes a '"
different fi~ld-accessed transfer gate using magnetically ~hard~ '¦
t'ransfer elements and special drive field pulses for transfer.
' Segments of two circuit elements have been ~oined I~
together before. For example, ad~acent T-bar channels'often -~
_ utllize double-T or I-bar configurations, as shown in the
M~chaelis article; supra, and elsewhere. U.S. Patent No.
3,713,119 to BobecX describes a particular circuit which re-
pre~ents a moaificat~on of T-bar and Y-bar circuit elements and
has common segments pairing the elements.
.
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lOS6948
One of th~ ob~ects o~ the invention ifi to permit con-
trolled transfer between mutually exclusive field-accessed
bubble propagation paths. Another object of the invention i~
to form composite circuit elements belonging to a plurality of
distinct, mutually exclusive bubble propagation paths. A further
; object of the invent;on is to implement newly discovered circuit
elements to form mutually exclusive bubble propagation paths.
Still another object of the invention is to permit controlled
transfer of bubbles between two portions of a composite circuit
element corresponding to distinct mutually exclusive bubble
paths.
In a preferred embodiment of the present invention
there is provided a field-accessed bubble propagation system,
comprising a sheet of magnetic bubble material, means for pro-
ducing and maintaining bubbles therein, a ferromagnetic overlay
circuit pattern operatively disposed on said sheet including at
least one discrete element having a straight stem portion with an
arm extending from one end thereof at an acute angle and an iso-
lated arm oriented at an acute angle with said stem portion on
the other side thereof having an adjacent end in spaced juxta-
position with said one end of said stem, and means for applying
a magnetic drive field in the plane of said sheet to propagate
bubbles along said stem portion to said adjacent end of said
isolated arm.
The term "mutually exclusive circuit element" as used
herein, means any one of at least two kinds of analogous ele-
ments, where a channel composed of one kind of element propa-
gates bubbles by means of a corresponding set of sequential
drive field orientations which does not propagate bubbles on a
channel composed of the other kind of elements, and vice versa,
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1056948
where both kinds of elements bear the same geometrical relation-
ship to the corresponding sets of field orientations which drive
them.
Using mutually exclusive circuit elements, some novel
and some previously disclosed, the applicants have discovered
that mutually exclusive circuit elements can be ~oined in a
manner which not only facilitates an efficient sharing of
portions common to both elements but also permits transfer
between distinct mutually exclusive circuits. By arranging
the composite circuit elements in series, parallel, inter-
connected bubble paths may be formed which are mutually exclu-
sive. One half of the integral channel formed by the compo-
site elements
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" 1056948
propagates bubble~ while bubbles on the other half of the channel
are stationary. Because of bubble-to-bubble repulsion, transfer
from one path to the other path of the common channel is con-
ditioned on the absence of bu~bles at corresponding position~ on
the path to which bubbles are to be transferred. Thus'the com-
posite channel can be used as a logic correlator. Composite
mutually exclusive eiements can also be used ~ ~ transfer
mechanis,m joining mutually exclusively field-accessed major and
minor loops in a memory organization. The circuit elements com-
prising the loo,ps are noncomposite circuit elements except fora transfer sect$on where the loops are tangent to each other.
' The transfer section is common,to both loops; and in the presence
of one set of drive field orientations, the transfer section acts
a part of the minor loop. ~nder another set of drive field
~5 orientations, the transfer section acts as a part of the ma~or
loop. Thus ~Ubble~ on the mlnor loo~ can be clroula~od lnto
posltion on the common transfer ~ection by one set of field
orlentat~ons,,a,nd",an,o,ther set of field orientations can subseq-
uently advance the bubbles along the major loop thus completing
the transfer. The transfer operation is characterized by the
absence of electrical conductors and the absence of speciàl
elements used solely for transfer. Only the elements neces~ary
for propagation exclusively on either loop are present in the
~transfer section. The elements of both loops in the transfer
2~ Jection are superimposed on each other such that certain portion~
of the elements are shared by the two loops.
A number of new mutually exclusive propagation circuits
are introduced, and the principle of composite mutually exclusive
elements is extended to these new circuit designs. While the new
circuits are designed primarily to propagate in the presenoe of
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0j-21-0253
1056948
particular sets of dis.-rcte drive ficld orientations, one clas~
of circuit elements also exhibits the property of discriminating
between the two directions of uniformly rotating'drive field~.
.. . .
BRIEP DESCRIPTION OF THE DRA~JING5
Figs. lA and 2-7 are schematic diagrams each illustra-
ting a pair of mutually exclusive bubble channels composed of
different types of mutually exclusive elements, according to the
.
invention, and driven respectively by the corresponding set of
drive field orientations d~agramatically represented in vector
form ad~acent to each respective channel.
Fig. lB is a cross-sectional view of a bubble chip. -
Fig. 8 is a schematic diagram illustrating mutually
- exclusive crow-foot elements driven respectively by the drive
field set ad~acent to each element.
Flgs. 9A and jB are schematlc dlagrams lllu~tratlng
respectlvely composite circuit elements formed by superimposing
on- of the crow-foot elements of Fig. 8 on the other. -'
ig. 10 is a schematic bubble circuit'diagràm illustra-
t~ng mutually exclusive major and minor crow-foot loo,ps~oined
by means of the composite circuit elen~nt of Fig. 9B.
Fig. 1,1 i8 a schematic diagram illustrating another
form of composite mutually exclusive crow-foot channel having
upper and lower paths in which bubbles are propagated exclusively
, by means of the two co~plementary sets of drive field orienta-
..
t~ons indicated in the drawings.
Fig. 12 is a schematic circuit' diagram illustrating
ma~or and minor crow-foot loops with a single composite transfer
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10~6948 i : -
element. , "
Fig. 13 i~ a schematic diagram illustrating ma~or and
minor crow-foot loops with a plurality of composite transfer
elements. .
Figs. 14 and lS are schematic circuit diagrams illustra-
ting eomposite ciow-foo~'ele~ents analogous to tho~e in F$g. 11.
' Fig. 16 is a schematic diagram illustrating a composite
mutually exclusive cireuit combining elements of the type shown
ln Fig. l in a manner analogou~ to the erow-foot composite
element's of Figs. 11, 14 and 15. ,,
Figs. 17-20 are schematic diagrams each illustrating'.
composite mutually exclusive circuits' eomposed of both crow-foot
elements and the type of element~shown in Fig. 1.
Figs. 21-24 are schematlc circuit diagrams illustratlng
eomposite mutually exelusive circuits eomposed of the type of
;~ elom~nt~ sho~n tn the eorresponding ~lgures 4-7.
' Fig. 25 1~ a ~ehematle diagram illustrating the
relationshlp between mutually exeluslve ma~or and minor loops ln
general, aeeordlng to the invention. _.
Fig. 26 i8' a sehematie diagram lllustratlng a field- ,
aeeesse~ bubble ehannel eomposed of diserete eireuit elements of
progressively varying eonfiquratlons.
- ~g. 27 ls a sehematie diagram lllustratlng a fleld-
w eessed bubSle ehannel compo~ed of eireuit elements l~ke those
~' 25 ln F~g. l modlfie~ ~n`'one seetlon to form a bubble eompressor.
Flgs. 28 and 29 are sehematie diagrams illustratlng
bubbl- ehannel~ ln whleh th~r- is an abrupt ehanqe ln the type-of
eireult element at one point along the ehannel.
Fig. 30 ls a sehematie dlagram lllustrating a honey-
eomb matrix bubble eireuit with parallel zig'zag ehannels.
.
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07 -21 -0253
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1056948
DESCl~;PTIG~ OF TIIE PRE~EP~RED EMBODIr~ENTS
In Fig. 1 a pair of bubble propagation channel~ 10 and
11 are composed of mu~ually exclusive circuit elements of soft
ferromagnetic overlay material which propagate bubbles in the
presence of respecti~e sets of in-plane discrete drive field
orientations 12 and 13. Each drive field comprises three
sequential vectors spearated preferably by approximately 120.
Drive field 13 contains vectors of opposite polarity to t~ose in ~ -
drive field 12. As a general note for the rest of this disclo-
sure, the illustrated drive field orientations for all of the
preferred embodiments (except Fig. 26) are discrete, pulsed
vectors. Any given set of discrete field vectors illustrated
in the drawings for driving bubbles on a given circuit in this
disclosure, always consists of three vectors, consecutively
angularly spaced elther by 120 as ror drlve ~leld set 12 (Flg.
1), for example, or by 60 as for drive field set 32 (Fig. 2),
for example.
The channel 10 comprises a plurality of serially
arranged elements 14. The circuit elements 14 form part of an
otherwise conventional bubble ~chip~ 15 in Fig. lB.- The chip
15 comprises a substrate 16 of nonmagnetic garnet which supports
an epitaxial magnetic bubble garnet layer 17 and spacing layer
18 of silicon oxide to which elements 14 are bonded. The chip
is subjected to a static magnetic bias f~eld orthogonal to the
plane of the magnetic bubble garnet layer 17 to maintain magnetic
bubbles therein. The bubbles are guided by the changing
magnetic poles formed in the elements by means of the drive field.
The other circuit elements referred to herein are similarly
appiied to the spacing layer of a bubble chip.
Each element 14 consists of a stem portion 20 having
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1056948
an angled arm 22 at one end making an acute angle ~ith stem 20
and an isolated bar 24 having one end juxtaposed with the junc-
tion of the stem 20 and angled arm 22. The isolated bar 24
makes an acute angle with respect to the stem 20 on the oppo-
site side from the angled arm 22. The element 14, nicknamed
the "dog-leg" element, resembles the crow-foot element dis-
closed in the copending Canadian application Serial No. 212,723
by Bailey and Doerr, with the portion of the stem between the
angled arms removed. The elements 14 are arranged serially so
that the stems 20 are in alignment. The drive field 12 con-
. tains a first field orientation parallelto the stem 20 and
: pointing away from the junction thereof with the angled arm 22.
The second vector in the drive field set 12-points along
angled arm 22 toward its intersection with the stem 20. The
third field orientation points along the isolated bar 24 toward
the end which is juxtaposed with the junction of the stem 20
and arm 22. The drive field 12 causes attracting poles to be
formed at the correspondingly numbered locations along each
dog-leg element 14. Thus when the field orientation 1 is
pulsed a bubble is attracted to the end of the stem 20 away
from the arm 22. The drive field orientation 2 attracts the
bubble to the other end of the stem 20 and the orientation num-
ber 3 attracts the bubble to the adjacent end of the isolated
bar 24. In the next cycle of drive field orientations, the
first orientation attracts the bubble from the isolated bar 24
to the adjacent end of the next dog-leg element 14. The rota-
tional order in which the drive field vectors are pulsed deter-
mines the direction of propagation on the channel 10.
The channel 11 operated by the drive field 13 is com-
posed of analogous dog-leg elements 26. Each element 26 is
symmetrical to the elements 14 of the channel 10 about an axis
of symmetry (not shown) perpendicular to the stem 20 of the
-- 11 --
1056948
elements 14. ~his type d perpendicul~r symmetr~ in e~fect re-
verses the dog-leg elements 26 with respect to the elements 14
such that bubble~ on the elements 26 can not be driven by the
drive field 12 but are dr~ven by the drive field 13. S~mi-
larly, the drive field 13 is incapable of propagating bubble~
on the channel 10. Thus the channels 10 and 11 are mutually `- !
exclusively field-accessed by their respective drive fielas.
- ~he numbered bubble positions on channel 11 correspond to the
labeled field orientations for drive field set 13. The type
of perpendicular symmetry which produces mutually exclusive
dog-leg elements is analogous to the perpendicular symmetry
discussed in connection with the crow-foot element disclosed
in the copending Canadian application Serial No. 223,370 by
Sandfort and Canadian application Serial No. 212,723 by Bailey
and Doerr. Similarly, the principle of parallel symmetry
discussed in the copending Canadian application Serial No.
223,370 by Sandfort can be extended in analogous manner to the
dog-leg circuit element. Closed triangular or parallel-sided
loops can be composed of dog-leg elements in an analogous
manner to the techniques disclosed in the above-mentioned co-
` pending Canadian applicationsSerial Nos. 212,723 and 223,370.
Fig. 2 illustrates a variation on the standard dog-
leg circuit of Fig. 1. A pair of mutually exclusive bubble ~;
channels 28 and 30 are exclusively field-accessed by means of
' the corresponding driv~ field sets 32 and 34. The "alternate"
! dog-leg element 35 in channel 28 comprises a stem portion 36
with an angled arm 38 at one end making an oblique angle with the
stem 36. An isolated bar 39 has one end in juxtaposition
with the junction between the arm 38 and stem 36 and also makes
an oblique angle on the other side with respect to the stem 36.
The corresponding set of sequential drive field orientations
32 comprises a first vector aimed along the stem portion 36
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1056948
away from the junction thereof ~ith the arm 38, a second vector
pointing along the arm 38 toward its junction with the stem 36,
and a third vector aligned with the isolated bar 39 directed
toward i~s juxtaposed end, The channel 28 is composed of a
plurality of serially arranged alternate dog-leg elements 35
with their stem portions 36 in alignment. Bubbles are advan-
ced to the numbered bubble positions along the channel 28 by
application of the correspondingly labeled field vectors 32.
The mutually exclusive channel 30 in Fig. 2 i8 com-
posed of alternate dog-leg elements having perpendicular sym-
metry to elements 35 of the channel 28 in a manner analogous
to the relationship between elements 26 and 14 in Fig. 1. The
numbered bubble positions for the channel 30 correspond to the
labeled vectors in the corresponding drive field set 34, As
~ in Fig. 1, the set 34 contains orientations which are opposite
- to corresponding orientations in the set 32.
' Fig. 3 illustrates a variation on the standard crow-
foot circuit element. A pair of mutually exclusive bubble
cnannels 40 and 42 are driven by corresponding drive field
- 20 sets 44 and 46. Each element 48 of the channel 40 comprises
a stem portion 50 with an angled arm 52 at one end making an
oblique angle with the stem 50 and intermediate angled arm 54
making a corresponding oblique angle on the other side of the
stem 50. The channel 48 is composed of a plurality of seri-
ally arranged elements 48 with-their stem portions 50 in
alignment. The first vector in the set 44 of sequential field
orientations is parallel to the stem 50 and points away from
its intersection with the arm 52. The second vector points
along the intermediate angled arm 54 toward its intersection
with the stem S0 and the third vector points along the
angled arm 52 toward the other end of the
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1056948 . 07-2l-b253
stem 50. Preferably the vectors 2 and 3 make 60 angles with
the vector 1. The numbered bubble positions along each element
48 of channel 40 correspond to the labeled field orientations
in the set 44. The mutually excluslve channel 32 is composed
of individual`alternate crow-foot circuit elements in a manner
analogous to channel 30 of Fig. 2.
Pig. 4 illustrates a pair of mutually exclusive circuit
channels 56 and 58 composed of symmetrical Y-shaped~elements 60
and 62 respectively.- The radial portions of each Y-shaped
element 60, 6,2 ar~ preferab}y separated by approximately the
same anqle, 120. Channel 56 is driven by the corresponding set
of drive field orientations 64 containing a first orientation I -
pointing radially outward algng one of the arms of the element
60, a second orientation directed along a second arm toward the
intersection of the arms and a third orientation directed
,xadially outward along 'he third arm of the element 60. Vectors
,: ~
1 and 3 preferably make 60 angles with the intermediate vector
` ?. The channel of symmetrical Y-shaped elements is constructed
by arranging the elements serially with corresponding portions
in parallel and adjacent radial arms in juxtapositifn. Attract-
ing poles for advancing bubbles along the channel 56 are numbered
in accordance with the drive field set 64. Channel 58 bears
; perpendicular symmetry to channel 56 and is driven ~y the com-
plementary set of drive field orientaions 66.
` Fig. 5 illustrates a pair of mutually exc lusive bubble
channels 68 and 70 composed of serially arranged ar~ow-shaped
elements 72 and 74 respectively. Each element 72, p4 comprises
a V-shaped head porfion having two arms 76 and 78 a~d a shaft
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, ' 07-21-0253
, 1056948. -
80 hav~ng one end joined to the ver~ex of the V-shaped head
portion. Channels composed of the elements 72 and 74 are con-
~tructed by serially arranging the elements with the shaft por-
tlons in parallel and.adjacent ends of the V-shaped head portions
~n justaposition. Preferably the'V-shaped head portion ~76, 78)
makes an angle of about 120 which i~ bisected by the ~haft por-
tion 80. The resulting channel resembles bird tracks, hence the
nickname ~chicken-claw" element'. The channel 68 is driven by
the corresponding set of drive field orientations 82 containing
preferably, three equally angularly spaced sequential vectors.
The first field orientatlon points along the shaft 80 toward the
' vertex of the head portion of each element. The second vector
points along segment ~6 away from the vertex, and the third
vector points similarly along the other segment 78 away from the
vertex Ruch that the bubble is transferred from one chicken-claw
- loment to the ne~t, as lndl¢ated by the numbered bubble ~osition~
for channel 68. Channel 70 bears perpendicu~ar symmetry to
, channel 68 ~d is ~riven by'the complçmentary set of drive field
'orientations 84 in a similar manner. ' --
Fig. 6 shows a pair of mutually exclusive bubble
ch~nnels 86 and 88 composed of mutually exclusive multi-element ,-
aircuit ~units n 90 and 92. In channel 86 a single circuit unit
90 18 composed of a first bar element 94, a pair of V-~haped
elements 96 and 98 having their vertices juxtposed at one end
of the bar element 94. A second bar element lO0 parallel but
~taggered with respect to the bar 94 is juxtposed between
adjacent ends of the V-shaped element 98 and the V-shaped element
96 in the next circuit unit 90. A channel of circuit units 90
.
--. 15 --
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1056948
is composed by arranging the circuit units serially with the
V-shpaed elements and bars in all of the units in parallel. The
channel 86 i~ operated by the corresponding set of three prefer-
ably equally spaced fleld orientations 102. The first field
orientation is parallel to the bar~ 94 and 100 pointing in the
direction of their ~uxtposed ends. The second field vector
points along corresponding segmenst of each V-shaped element
96 and 98. Similarly the field vector number 3 points along th-
other corresponding segmen$s of the V-shaped elements 96 and 98.
Two cycles of the drive field orientations arë necessary for
bubbles to traverse one of the circuit units 90. Consider one ~
bubble entering the channel 86 from the left; the first field - v
orientation places the bubble at the upper left-hand end of the
V-shaped element 96. m e second orientation attracts the bubble
to the vertex of the element 96. The third field orientation
attra¢ts the bubble to the adJacent end o~ the bar j4. In the
~ubsequent cycle of th~ fiold set 102, the first field vector
,
draws the bubble to the vertex of the V-shaped element 98; the
s-cond~ieid vector attracts the bubble to the right-hand upper
end of the element 98 and the third field vector attracts the
bubble to the adjacent end of the bar 100, from which point the
double cycle~ is repeated. The ele~ents 92 in channel 88 of
Fig. 6 bear perpendicular symmetry to the elements 90 in channel
86. Channel 88 is operated by the complementary corresponding
set of drive field orien~ations 104 in a similar manner. Because
of the staggered arrangement of the propagating elementq, bubbles
traveling on channel 86 or 88 execute a waddle-like motion, hence ~ -
the nickname ~duck-step" circuit.
Fig. 7 illustrates a pair of mutually exclusive bubble
channels 106 and 108 composed respectively of multi-element
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07-21-0253
1056948
,. . . .
, .
circuit units 110 and 112. Circuit unit 110 includes a bar-
shaped element 114 and a pair of crisscrossed elements 116 and
118 having their corresponding ends in linear ~uxtaposition with
th~ correspond~ng end of the bar 114. In relation to the pro-
pagation channel formed by the ~xtposed ends of the elementsli4, 116 and 118, the bar 114 lies on one side and the criss-
crossed elements 116 and 118 lie on the other side. Preferably
the elements 114, 116 and 118 all make 120~ angles with each
other. A circuit channel ls constructed ~y arranging a plurality
of so called "X-bar" elements in series such that the juxtaposed
ends of all of the eiements are in alignment to form an approxi-
m~tely straight line propagation channel. Corresponding portions
of each circuit unit 110 are parallel to each other. The channel
106 i~ driven by the corresponding set of three preferably '
equally spaced fiela orientations 120. Ihe first orientation
~ parallel to the bar 1~4 pointlng toward the propaga~lon path.
The second and third field vectors are parall¢l respectively to
arisscrossed elements 116 and 118, and point toward the propa-
gation path. The bubble positions on the channel 106 ~r~ -
numbered in accordance with the labeled field vectors in the
set 120. The channel 108 is similarly composed of a series of
X-bar c~rcuit units 112 which bear perpendicular symmetry to the
elements of channel 106. The channel 108 is operated ~y a cor-
J responding set of complementary field orientations 122 in a
r 25. similar manner.
Fig. 8 illustrates a pair of mutually exclusive crow-
foot elements 124 and 126 operated by corresponding sets of
complementary drive field orientations 128 ana 130 in accordance
with the teachings of the above-mentioned copending
Canadian patent application Serial N~. 212,723
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lOS6948
by ~a~ley ~nd Doerr. Figs. 9A and 9B illustrate composito cir-
cu~t elements 132 and 134, respectively which are recognizable
~uperimpositions of the two elements 124 and 126 in Fig. 8.
In both composite elements 132 and 134 the stem portion 138 i~ ,
' 5 common to the two spearate elements 124 and 126 (Fig. 8) which , ~ -,
have been superimposed on each other. Whlle element 132 con-
tains no d~scontinuities, in element 134 the straight line 136 (F ,-~
(Fig. 9A) which crisscrosses the stem 138 is broXen at its end~ ~ -
and at the stem 138 to form two aligned, discrete straight por-
tions 140 and 142 to enhance the pole formation.
' Fig. 10 illustrates mutually exclusive major and minor
, propagat~on loops. Bubble data would normally, be stored in the
~' minor loop and transferred to or from the major loop for read-
- ; ' out and write-,~n. The section of the major loop depicted in
Fig. 10-is composed of crow-foot elements 24 (Fig. 8). The
. .
mlnor loop 1~ ln the ~orm o~ a reotangle wlth the upper 8i~0
form~d by crow-foot elements ~26' each of which bears parallel
~ymmetry to elements 126 of Fig. 8 in accordance with the
teachings of the above-mentioned copending Canadian
patent application Serial No. 223,37~ by Sandfort. The
right and left sides of the minor loop are composed -,
of chicken-claw and duck-step circuits 144 and 146 respectively.
The four compo~ite elements 134 are common to both the ma~or and
minor loops. Because of the dual structure of the elements 134,
these elements contain the necessar,y crow-foot element~ 126 for
paral~el opposite propagation with respect to elements 126' of
the minor loop. m us the composite element 134 belongs to the
m~nor loop. Yet the eiements 134 also include the crow-foot
elements 124 within ~heir dua?'structure andtherefore the com-
poslte elements 134 also belong to the ma~or loop. In the
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07-21-0253
1056948
corresponcling set o~ drive field orienta~ions 148, the major
loop will be nonpropagating, while the minor loop will recir-
culate bubbles, and the composite elements 134 will behave as
if they are part of t~e minor loop. In the corresponding set
of complementary field orientations 150, the converse operation
occurs: the minor loop is stopped and the major loop propagates'
bubbles with the composite elements 134 beha~ing as if they were
part of the major loop. It should be noted in particular that
the propagation pa~h along the stem of each composite element
is the same whether the bubbles are being propagated under the
control of field set 148 or 150. Thus no transfer operation is
necessary. For example, to write four bubble bits into the
minor loop, the four,bit "train" would be advanced along the
major loop by means of the drive field set 150 until the train
was located on the four corresponding composite elements 134.
` At thls moment the ~ield set 150 would be stopped and the com-
-'' plementary set 148 would be s,tarted to control the composite
elements 134 as part of the minor loop thus "sidetracking" the
four bit train into the minor loop, off of the major loop. ~he
converse of this operation would accomplish readout of the
minor loop onto the major loop.
Fig. 11 illustrates another kind of composite crow-
foot element 152 in which two partially common, mutually exclu-
sive crow-foot elements share an intermediate angled arm 154
that~has separate parallel stem portions 156 and 158. Thus
joined, the two identifiable crow-foot elements present a single
composi~e-element 152. Fig. 11 shows a serial arrangement of '
identical composite,crow-foot elements 152. m e upper stems 156
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07-21-OZ53
1056948
. . .
are all in alignment as well as the lower stems 158. The
allgned stems 156 for~ an upper ~ubble path and the aligned
' stems 158 form a lower bubble path. The set of drive field
';~ orientations 160 operates the upper bubble path ln accordance
with the correspondingly numbered bubble positions~ and the
set of complementary field orientations 162 operates the lower
path in a similar manner, as indicated by the correspondingly
lettered bubble positions. ~ecause of the opposite relation-. .
ship between drive field sets 160 and 162 wh$ch operate the . .
upper and lower bubble paths, the paths, although interconnect-
ed, are mutually exclusive. However, bubbles on either path
: , . .
. c~n be transferred via the shared common intermediate arm i54
' of each composite element 152. For example, if the lower path
or track l~ operatlng by ~irtue Or the drlve ~ield set 162 and
bubbles have ~ust been attracted to the position b by means
. of the vector b, switching to the drive field 160, starting
. with the opposite vector number 2 will cause the bubble on each
oomp w ite el-ment ls? to traverse the common arm 154'to'th-
bubble position 2 on tbe upper.track and from there to th-'`
bubble position 3 as the sequence of the drive.field set 160
.oontinues. ~ransfer can only occur from the.lower to the upper
track when bubbles on the lower track are at position b. If
. the bubbles are at e~ther position.a or c when any one of the
orientat~ons ln the drive field set 160 for the upper track is .
pulsed, transfer will not occur. Accordingly, by properly - '
. timing the change-over from field set 162 to the complementary-
' sot 160, transfer or no transfer can be executed on command.
. .
. 20 ~ .
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1056948
Thus the composite elements 152 can behave as two distinct
mutually exclusive crow-foot elements or a~ a single element
common to both drive fleld orientations 160 and 162 depending
on the point at which t~e drive field sets are interchanged.
The transfer operation in Fig. 11 is also determined
by the presence of bubbleg already on the other track, l.e.,
the one to which bubbles are to be transferred via the shared
element 154. To transfer a bubble, for example, from Dosition
b on the lower track to position 2 on the upper track, there
cannot be a hubble already at po~$tion 1 or 3, or at
position 2, on the same stem 156 o$ the upper track. Bubbl~
- at position 1 or 3 would,tend to move to position 2 when vector
number 2 was pulsed and thus prevent transfer of a bubble at
po~ition b due to magnetic repulsion. Thus, to this extent the
transfer operation i8 a logic function of the positions of bubbles
on the two tracks.
Flg~. 12 and 13 illustrate major~minor loop configura-
tion~ employing re~pectlvely a single one and a plurality of
¢ompos~te, shared-arm transfer elements 152. The parallelogram
shape of the minor loo~ lndicated ~n Figs. 12 and 13 is accord-
ing to the teachings of the above-mentioned copending ap~l~cation
by Sandfort~ The systems in Figs. 12 and 13 operate in a
.
manner analogous to.the system which would be presented by re-
placing the com~osite ele~ent 134 of Fig. 10 with corresponding
25 verslons of ~he composite shared-arm elements 152 of Fig. 11.
There is an important distinction, however, between the system
actually ~hown in Fig. 10 and those:indicated in Figs. 12 and
13. In Fig. 10 the major and minor loops are not completely
d~stinct. That is, in order to run a minor loop exclusive of a
3~ ma~or loop, the sy~tem of Fig. 10 requires that a portion of the
'
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07-21'-0253 '
; . 1056948
ma~or 1PO~ be borrowed by the minor loop, and vice versa. In'
Flgs. 12 and 13, however, the m~nor loops can be operated com-
pletely exclusively of the ma~or loops without using any portion
of th'e ma~or loop, an~ vice versa. The reason for this, as
dl~cussed in c4nnection with Fig. 11, is that transfer from the
upper to the lower track ig conditional on switching from one
field set to the other at the rlght time. Thus, transfer can
be deliberately avoided.' In Figs. 12 and 13, the major loops
. in this case are operated by the field set 160 of Fig. 11 and
the minor looFs are operated by the corresponding complementary
field set 162 of'Fig. 11. In operation, there is an important
distinction between the systems of Figs. 12 and 13. The system ~ .
of Fig. 12 can only accomplish ~sorial" transfer, while the
system of Fig. 13 can accomplish parallel transfer across a
plurality of composite el~ments 152 at once.
Mutually exclusive elements can be ~olned 1n many dlr-
f~rent ways as shown in Figs. 14 and 15 for crow-foot composites. ;
A composite crow-foot element 164 IFig. 14) is formed by two
mutually exclusive, recogn~zable orow-foot elements which share
? un end arm.166. The elements 164 sre arranged in series to pro-
vlde upper and lower bubble tracks in an analoqous manner to the
shar d intermediate arm composite element 152 of F~g. 11. In
Fig. lS another type of composite element 168 is composed of two
reoognizsble mutually exclusive crow-foot elembnts in wh~ch the
intermed$ate arm of one element is'sharea as the end arm of the
other element, the shared segment being indicated'at 170 in Fig.
lS. Again the elements 168 are arranged in series to provide '
upper and lower bubble paths whose operation is similar to that
of the oircuits of Figs. 11 and 14.
,
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' 10569~8
Fig. 16 indicates the analogous treatment for the
dog-leg circuit of Fig. 1. The composite circuit unit 172 in-
cludes two mutually exclusive dog-leg circuit elements in which
the isolated bar of t~e upper element is shared as the angled
end arm 174 of the lower element. The composite elements 172
are arranged in series to form upper and lower tracks as in the
crow-foot composite circuits. Propagation on the upper and
lower tracks is accomplished respectively by means of the field
sets 176 and 178. Transfer, if desired, can be effected, for
- 10 example, by changing over from one field set to the other from
the b to the number 3 vector, and vice versa.
Figs. 17-20 indicate analogous arrangments in which
composite mutually exclusive elements are composed of one crow-
foot ele~ent and one dog-leg element. For example in Fig. 17
the composite circuit unit 180 is composed of a discretely re-
cognlzable crow-root element and a dog-leg element ln whlch the
.
intermediate arm of the crow-foot element becomes the isolated
bar 182 of the lower dog-leg element. The upper and lower
tracks are operated by the corresponding complementary field
sets 184 and 186 as indicated by the numbered and lettered bubble
pos~tlons. The transfer operation is similar to that for the
composite dog-leg element 172 in Fig. 16.
Fig. 21 illustrates composite chicken-claw circuit
elements 188. Fig. 21 corresponds to Fig. 5 but differs in that
channels 68 and 70 of Fig. 5 are joined in Fig. 21 by means of
the common shaft 190. Bubbles are propagated through the number-
ed bubble positions on the upper iigzag track by means of the
correlspondingly numbérea dri~e field set 192. On the lower track,
bubbles are propagated through the lettered positions under the
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10~i6948 --
control of the corresponding complementary drive field set 194.
As in the crow-foot and dog-leg composite elements, the chicken-
claw composite element provides a transfer path between the
upper and lower path via the common shaft 190 of each element
188. Thus, reversing the vector a in set 194 to begin opera-
tion of field set 192 with vector number 1 causes transfer from
position a on the lower track to position 1 on the upper track
if bubble positions 1, 2 and 3 of the same composite element ~-
188 are not simultaneously occupied.
10Figs. 22-24 represent analogous marriages of the
upper and lower circuit channels in Figs. 6, 7 and 4, respec-
- tively. The upper and lower bubble tracks in each composite
circuit in Figs. 22-24 are exclusively operated by the upper
; and lower field sets indicated in each figure. It should be
noted, however, that the duck-step system of Fig. 22 provides i~
two different transfer paths between the upper and lower cir-
cuits: One between bubble positions 3 and c and the other be-
tween bubble positions 2 and b. The only way to positively
avoid transfer in the duck-step composite circuit is to stop
lower path propagation at positions a before operating the
upper path, or to stop upper path propagation at positions 1
before operating the lower path. Of course, as in the other
circuits, for transfer to occur, neighboring positions on
the track to which transfer is desired must be vacant, as
well as the position to which a bubble may be transferred.
Fig. 25 represents a general diagram of a major/
minor loop organization. A common section s joins the major
and minor loops. Depending on the type of circuit elements
used in the rest of the major and minor loops, any of the com-
posite circuit elements shown in Figs. 9-24 may be employed to
implement the section s permitting exclusive propagation in
either the major or the minor loop or field-accessed transfer
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I056948
between the loops. Either one of the loops can have the
geometry of a triangle, parallelogram, rectangle or analogous
shapes as described in the above-mentioned copending applica-
tions by Sandfort and by Bailey and Doerr.
In Fig. 26 a bubble channel 196 starts out on the
left-hand end with a standard crow-foot element 198. The arms
of the crow-foot element are progressively reoriented in succes-
sive increments from element to element to the right of the
first element 198. Element 200 for example, has staggered per-
pendicular arms on either side of the stem portion. To the
right of the perpendicular armed element 200, the elements'
arms continue to reorient and the elements gradually assume the
form of an alternate crow-foot element 202 (c.f., Fig. 3). The
arms of the elements continue to flatten out against the stem
portion until they disappear altogether at element 204. Placed
under the control of a rotating drive field 206, the circuit
196 exhibits differential behaviour along its length. For
example, in the vicinity of the standard crow-foot element 198,
rightward propagation occurs in the counterclockwise field.
Bubbles come to a full stop, however, at element 200 since the ~
poles that are produced in element 200 are nonproductive in
propagating bubbles. In the vicinity of the alternate crow-
foot element 202, propagation is rightward again under the con-
trol of the drive field 206. The drive field is ineffective,
however, to propagate bubbles on the straight line elements 204.
Thus, in the same circuit there are portions which operate and
other portions which fail to operate.
Fig. 27 illustrates a bubble channel 208 composed of a
series of standard dog-leg elements 210, like element 26 in Fig.
1. One section 212 of the channel 208, however, is composed
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07-21 0?53
1056948
of a plurality o~ adjacent bars 214, parallel to the isolatod
bar element of the standara dog-leg element 210. In the sequen-
tial dirve field set 216, bubbles may be advanced along the
standard dog-leg port~on of the circuit in either direction.
Upon approaching the parallel bar section 212, howeverj~ succes-
sive bubbles will become stacked up consecutively on the aligDed
ents of the bars 214. Thus, the channel 208 operates as a
bubble compressor. The nonpropagating elements 200 and 204 in
Fig. 26 may also serve as a bubble compressors.
Fig 28 shows a channel 218 composed of a standard
dog-leg circuit element section 220 and alternate dog-leg sectio
222 arranged in series. Section 220 propagates left~ard under
the control of drive field set 224, and section 222 propagate~
rightward under the control of the drive field set 226.
Fig. 29 illustrates a bubble channel 228 with ad~acent
so~t~ons 230 and 232 compo~ed Or standard crow-root element~
ha~ing parallel symmetry, respectively, such that under the con- !
trol of the same drive field 234, section 230 propagates left-
ward and section 232 propagates rightward. _ .
In Fig. 30 a honeycomb matrix 236 permits propaqation
ln nonparallel directions. The matrix includes six verticai
veins of 60 sawtooth continuous,overlay circuits 238, 240, 242,
244, 246 and 248. Alternate veins are parallel and ~in phase~
for example, veins 238 and 242 and veins 240 and 244. Ad~acent
vein8, for example, 238 and 240 are reversed or 180 out of
pha~e such that if they were sawtooth waveforms they would have
opposite polarity. At-prog~essively staggered intervals between
~uccessive pairs of ad~acent veins, vertical bar elements 250,
252, 254, 256 and 258 are inserted in the matrix 236. Under
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07~ 3
1056948
the control of the sequentially pulsed drive field set 260, any
bubble on the veins 238-248, before encountering one of the bars
250-258, advances downward under the control of field vectors
1 and 2, which are aligned with alternate segments of the veins.
Upon reaching one of the upper ends of the bars 250-258, a
bubble advancing to bubble position 2 on one of the veins will
next be attracted to the adjacent end of the bar at bubble
position 3 corresponding to field vector 3. The next field
voctor 1 completes transfer of the bubble to the~next ad~acent
vein of the matrix. A~ indicated by the numbered bubble poRi-
tlons, this transfer operation will continue until no more
vertical bars are encountered at which time the bubblc wi~l re-
sume downward propagation.
Diagonal movement on the matrix 236 ~s dependent on
the rotational order of the drive field set 260, which in this
caso ls ooudterclockwlse. I~ the order Or the same ~leld orlen-
tations was reversed (e.g.,3, 2, 1), the field vector 1 would
follow the field vector 2 and the bubble would continue down the
~ume veln ignoring the presence of the vertical bar. For the
complementary field set 262 (a,b,c), bubbIe propagation along th~
v ins would normally be in the upward direction by virtue o~ the
field vectors a and b. As indicated by the progress of the
lettered bubble positions, when a bubble propagat~ng upward on
the vein 248, for example, encounters the bar 258, the bubble
~tarts a diagonal propagation pattern analogous to that for the
. bubbles under the control of complementary drive field 260. The
iagonal path through the honeycomb matrix 236 will be ~een upon
~nspection to represent another kind of composite mutually
exclu~ive dog-leg circuit. The bubble matr~x as illustrated in
.
: ~ 27 -
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1056948
Fig. 30 has significance for bubble logic and may also be ~ ,.
applied in the area of bubble "displaysn.
' Those skilled in the art will recognize that many
broad principles are illustrated in this application in the form
of specific embodiments which often contain special features that
are not critical to the principle employed. For example, the
precise angles, lengths, spacing and relative sizes of the
elements shown herein are parameters which may be optimized for'
a particular circuit by conventional methods. In this regard, the
the pole analysis technique discussed in the above-mentioned
coepnding appl~cation by ~ailey and Doerr can be used to
~ advantage.
- The present embodiments are therefore. to be con~idered
- ln all respects as illustrative and not restrictive, the scop-
and principle of the invention being indicated by the claim,
ratper than by .the.foregoing description, and al~ cnange~ wnich
come within the meaning ar.l ~ange of equivalence of the claims
are therefore intended to be embraced therein.
' r
., " , ~ .
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'' ''
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