Digital magnetic core memory with sensing amplifier circuit

Milligan, G. C.

English

NASA Technical Reports Server

REPLY TO 
ATTN OF: G P  
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON. D.C. 20546 
June 30, 1971 
MEMORANDUM 
~ ~ ~ / ~ c i e n t i f i c  & Technical Information ~ i v i s i o n  
Attn: M i s s  Winnie M. Morgan 
FROM : ~ ~ / ~ f f i c e  of Assis tant  General 
Counsel f o r  Patent Matters 
SUBJECT: Announcement of NASA-Owned U.S. Patents  i n  STAR 
I n  accordance with t h e  procedures contained i n  the  Code G P  
t o  Code US1 memorandu,m on t h i s  subject ,  dated June 8, 1970, 
t he  attached NASA-owned U.S. patent  is  being forwarded f o r  
abs t rac t ing  and announcement i n  NASA STAR. 
The following information is provided: 
U.S.  Patent No. 
Corporate Source : California I n s t i t u t e  of Technology 
Supplementary 
Corporate Source : J e t  Propulsion Laboratory 
NASA Patent  Case No.: XNP-01012 
Please note t h a t  t h i s  patent  covers an invention made by an 
employee of a NASA contractor .  Pursuant t o  §305(a) of t he  
NAS Act, t he  name of the  Administrator of NASA appears on the  
f i r s t  page of t h e  patent ;  however, t he  name of the  ac tua l  
inventor (author) appears a t  t he  heading of Column No. 1 of 
t h e  Specif ica t ion,  following the  words ". . . with respect  t o  
an invention of .  . . ." 
~ a y l e  Parker 
Enclosure : 
Copy of Patent  
https://ntrs.nasa.gov/search.jsp?R=19710019449 2020-03-17T03:15:18+00:00Z

2 
The sensing circuit can be comprised of cascaded 3,394,359 
hl;E%lBORJ,Y SESSG RxqpEHIFPF?iG ME.4FbS sfages capable of introducing signal gain. In a P m f ~ r e d  
A d m i ~ i ~ m t o a  of Safb'onal Aero- embodin:ent of the isvention. each Stage hci~d+cs :;S 16- 
and sPwbt ~ ~ ~ g ~ ~ ~ b ~ ~ i ~ ~  reTed to an stable nagrielic core, capabEe of  i ~ t r o d a c i n ~  flux W D -  
of George @. MilEEgaw, Afladena, M i f .  g Thus. the current divefled from the in:erroghlion wind- 
Filed M a p  21. 1954. Ser. No. 3 6 9 3 8  ing of the memory core can be used to zet a first sD@ 
4 Claim (61. 3 6 1 7 4 )  core. Tfie fist  stage core can then be similarly jnterro- 
gated at a 'later time so that current diverted from n ' t ~  
inrenogation winding will set a second stage core. By 
A B S m e  OF TiPE DlSCEOSLW proper use of the winding turns ratios by pro- 
gressively increasing the size af the cores in sucassi7ve 
A magnetic core memory is described in whicic5 sensing stages, an output s ipaI  will be pr Jvided by the Iast sens- 
circuits are connected in parallel with inte&g:rte wind- i7g circuit stage which signal has a considerably greater 
in@ for sensing the slate of memory cores coupled t o  magniiude thajl that normally provided by the nlemom 
the windings. The memory is comprised of a plurality of core. 
magnetic cores respectively arranged in muVs and col- The teachings of the invention are ns equally applicabfc 
umns. Each of the magnetic cores constitutes a multi- to memories using a11 known types of magnetic cores. 
aperture device and is rapable of defining a "I" state, a n u s ,  the sensing technique introducrd herein can h used 
''0" state, and a "prime" state. A plurality of inte~ogate with most single aperture and mulciaperture magnetic 
windings are protided with each being coupled to the 20 core memories. A typical latter type of m e m r y  is dis- 
cores of a difFertnt one of L h  coiumns. A plurality of closed in detail herein. 
sensing circuits are provided wtih each being connected The novel feazures that are considered cha;sc?eristiis: 
in parailel with a different one of the interro_eate wind- of &is invention are set forth with pwticdarity the 
ings. Interrogate means apply s ipais  to the inrerropate zppended .-]aims. m e  invenrion itself both as 10 i t s  Or- 
windings in a direction to switch the cores coupled thereto 05 ganization and nethod of operation, as  wcll as addifiantd 
to a "I" state. Those core elements defining a "prime" objects and advantages thereof, will best be undcrstocPd 
state will present a relatively high impedance so that the from the follou,ing description when read in c~mection 
applied signal %ill be diverted to the Iower impedance with the accompanqing dia~in_cs, in which: 
FIGURE 1 is a diagrammatic view of a typicai mag:- 
20 netic men'lory core illus!rating the various windings con- 
ventionally coupled thereto together with sense amp& 
ORIGIN OF INVEmION fying means in accordance with the invention connected 
The invention descr!'bed herein was made in the per- the sinding; 
formance of work under a NASA contra3 and is subject FIGURE 2 is a diagrammatic illustration showing the 
to *he provisions of section 305 of Aero- 33 various flux states whizh can be assumed by the core of 
nautics and Space A d  of 1958, Public Law 85-568 (72 FIGURE I; -and 
Slat. 435; 42 U.S.C. 2457). FIGURE 3 illustrates a substantially con~entianal 
Tfjs invention relates generally to memory apparatus memory matriv and sense a m p ' i f ~ ~ ~ ~  means in accord- 
capable of storing digital information and nore  p&c- qo ance 'he in'eniion u= 
ufarly to improved sense amplifier means for use wiih Attentics is now calied to FIGURE I of the drawinm 
digi:al memories of tbe magnetic core type. which ii!ustrates a cooventionzl t x o  aperture magne~6: 
laost all digital and data appa- core device 10, often called a transfluxor. The transBuxor 
ratus employ a  memo^ c0mprjse-J of bistable magefic bo& a large and a smdl aperture are: 
cores for storkg digita] information. spaced so as to define three l e g   respective!^ jdeatified 
cores have two s t abk  states of magnetic remanence which 45 as 12,14, and 16. 
can be respectively used to represent "O" a d  "1" binary FIGURE 2(a) diagrammatically illustrates one state 
agits, ~~~h mametic core in a inemory can be switched of Aux orientation in the transduxor I.@. It will be noted 
to a rernanent state by proper that all of the Aux is directed in a counterciock~~se dime- 
tion. FIGURE 2 ( b )  illustrates a second stzte of flux nri- currents thereto. The state of a 
50 entation in tk,e fiux is directed in 3 c!ocl.%ise dirm- magnetic core can be intesrogaied by determining whether 
or not the core switches uhen signals are applied to tion about the small aperture. FIGURE 2(c) ilfusmtes 
ihprero for driving cote to a a third state of Acx cr-Lntation in the transfluzor &O and 
state. Whether or not the core suitches is conventionaIly diiiers from the state shown in RGL'lE Z(b) by ~ ~ i f i e r r ;  
of the fact that the ffux is directed in a cot*nterclwkwise detected by sensing u.he"iber a signs] is indcced in a sense 55 direction around the 
apsnure. FrGURE Zib)  iilus- winding co'upIed to the core. The signal so induced in the 
sense winding is usualTy of a amplitude aQd traies a fourth slate of fim orientation in which all of the 
consequenuy secsitive end expensjve sense mpli- flux in the transfiuxor is directed in a clockwise dime- 
fiers are usually required to detect the induced signal. tion. 
It is an object of the present invention to provid: im- As will be more readily nnclerstood hereinafter, the. four 
proved sense means suirable for Go flux orientations definable by the transfiuxor I@ permit 
magnetic core digital memories. the transfluxor to be interrogated non-aestmctively. n a t  
Briefly, in accordance with :he eresent invention, ref- i5, whereas the information stored in conventional sh&le 
atively low impedance sensing circuit is ,-bnnccfed in aperture cores is destroyed when the core is intenogated, 
parallel with the in te r ro~t ion  winding of a core such the information is not so destroyed when the trznsBuxor 
that when an interrogation signal is applied to the wind- 85 is interrogated. AS a consequence, the Usc of a transfirnor 
ing, a significant portion of the interrogation signal will memory permits the eiimination of the wrib-alkir-reed 
be steered to the sensing circvit, rather rhan.traverse the phase normally required in the use of single aprtuae 
interrogation winding, if the interrogation winding pre- magnetic core memories. As has been pointed out, 
scnls a rriatively high impedance. The inlkrrogation wind- teachings of the invention herein can be used cquajly 
ing will present a high impelfiance to signal; which fire wcll with ciihcr single o r  multiple aperture mrtgneric 
of a polarity tending to switch the core. cores and it should be understood tba't the Pluli~lathn at 
ity must be applied ta ipindii7gs cor~pled to the n"cns9w.- 5 
or. Thus, driw =led vu'in&ng A connec:ed beween a 
single-pole dochie-~Erciw, supit& 18 and groucd k coupled 
to leg 12. Sa.itch 18 can selectively connect one end of 
winding A to o ssnct~e of either positive or negative poten- 
tial. A prime winding B is connected between a single- 
pole double-throw switch 29 and ground and is inductive- 
ly coupled to leg 3.11. Slmitdy, winding C is connected 
between single-pole singe-throw switch 22 and pound 
and is also inductivezy coupled to leg 14. Interrogate wind- 
ing D is conmxted between single-pole single-&row switch 15 
24 and ground and is inductively coupled to leg 16. 
By connecting switch 18 to the source of posi"te poten- 
tial, a positive current will be developed in winding A 
which will orient the Eux downwardly in leg I2 to there- 
by drive the transfirnor 10 to the flux orientation state 20 
will be referre8 to as the binar] digit "0" state. If switch fluxor ma-meri-ric cores of the type shown in FIGURE 1. 
20 is closed concurrently with witch I5 being connected The rnalrix iljustrated in FIGURE 3 is comprised of three 
to the source of negative potential, the flux in leg 14 will rows and three :olurnns but it of course should be appre- 
be prevented from turning dounwardly and as a conse- 30 ciated that a matrix of any s i z  can be constructed in 
quence the transfluxor will he driven to  he flux orimta- accordaatx with the invention- Eazh matrix row can be 
tion stale illustrated in FIGURE 2 ( h ) .  This state will used to store a different comp'Lter word. Thus, it is de- 
be referred to as the binary digit "1" stzte. It is to be sirable to be able to write infomation into or read in- 
coted that if su<tch 20 is tined uhen saitch 18 is open, formation from all of h e  trms&aors in m y  pzflicuHz;r 
it nil1 have no effect on the flLix orientation in tnnsfiuxor 3 j row, in parallel or sirnultaneody. Each matrix c o l ~  
XQ if the transfluxor defines either the "clear" state or the includes transffuxors \r;hich sfore cmesgonding bits of 
"0" state. If the "clear" state is defined, the signal de- different words. 
veloped in winding 3 will merely lend to further saturate More particularly, the transEnxors of row 1 of the 
tbe flux in leg. 14. If the "O" state is defined, the signal in matrix are  identical!^ threaded by wiridingA1 and wind- 
winding B will tend to re-o~eot  he flux in leg 14 but will 40 ing CP respecrire;:~ corresponding lo winorrrgs A and 62 
be unable to ii:asmuch as it will be insuScient to ye- oi FIGURE 1. The transfluxors of coiurnn P are similady 
%erst the flux in the large 1c.g I2 and ca:, only further coupled to windings BI and Dl  respectively correspond- 
saturate the fiux in the srna!I leg 16. ing to =indings B and D of FiGURE 1. A diEerent sense 
- 
to%ansr";uxors defining a "'1" prime state will present a 
hisb impedance and -ill thus steer current into the sense 
amplifying circuit 26 connected in paml:el therewith. 
The sense srnpiifying circuits 26 can comprise a plu- nal gain. Enasrnnc-fr as sensing in zccordznce 
rality of cascadcc! stages, each stage including a bistable 5 vention herein is a c c o ~ p l i s h d  by apparatw 
.mzgriefrc core. 'Ems. the sense arnpliQing circuit con- 
nected to winding Dl  includes cores 50 and 32 in the first 
and scond stages thereof. Winding 34 is cennected be- 
tween switch 44 associated wiih winding Dl, and ground. 
When current is diberted into winding 3.1 the 9ux in core 
3BD will FA switched in a clockwise direction. A winding 
36, having a greater number of turns rhan winding 34. is achieved if serial a 
also provided on core 30 a.nd is connected between ground 
and single-pole double-throw switch 38 adapted to engage 
a source of positive po:en,ial. Connected in pal-allel with 15 
winding 36 is a series circuit including winding 40 and 
diode 42. Winding .30 is inductively coupled to core 32 
which has a winding 44 also coupled thereto. Winding 44 I. A digital memory system comprisirrg: 
has a grearer number of turns than wind.ing a. a pturii!ity of mzziietic cores respectively arranged in 
In the opera:ion of the sense ampEfying circuit 26, 20 rows and columns; 
w h n  the transfluxor memory core is interrogated, core each of %.id magnetic cores being capable ai defining 
30 will be switched to a set state if the trans3uxor memory at least three different states of magnetic caenance 
core associated therewith defines a "1" prime state. As respectively identifiable as a "1'" state, "0" state, 
noted, the current diverted from interrogation winding Dl and a "prime" state; 
into winding 34 can be significantly greater than the cur- 23 
rent normally derived from a sense winding coupled di- 
rectly to the trzilsRuxor memory core. After the inter- 
rogation signal has been applisd througl switch 24 to the 
interrogation winding Dl, the switch 38 is closed to ap- 
ply a current to uinding 36 to reset the czrc 30. If the 30 
core 30 had been set. Core winding 36 will present a high 
impedance to the current applied thereto and thus, the 
current applied through switch 38 %ill be diverted into 
winding 40 through diode 42.  The curreal through wind- 
ing 40 will set core 32. If on the other hand core 30 had 33 
not been initially set, ~iipding 36 ui!l not present a high 
impdaace and core 32 ail1 not be set. The ieiting of the 
core 32 by the current diverted in:o winding 40 will in- 
duce an output sig2al in winding 44 shich has an ampli- 
tude considerably greater than the signzl derivable from 40 
a sense winding coupled to the transfloxor menory core. 
The sense amplifying circuit 26 provides a significantly 
larger output s i ~ c a l  than the input signal provided thereto ings, each of said sensing circuit means presenting an because of the fiux gain introduced therein. That is, in 
each succeeding stage of the sense a~nlif ier  26, a greater 46 impedance to said interrogate means which is Jess 
arnount of Bux is swilched to thereby ~rovicie a. !arger than said high impedance and more than said low in- 
signal at the output uinding of the last wnse anplifying pedance presented by said cores. 
c i rc~ i t  stage. The amount of flux switched in each of the 2. The combinaiion of claixn 1 wherein said sensing 
is determined by ;he ampere circuit includes at least one signal amplifying stage. 
turns microsccon~s thereto a9itfi the limit of 50 3. The combination of daim 2 wherein said signal i i a ~  
course being defined by the core and dimen- p!ifling SQge includes a sensing magnetic GOr:: responsive 
sions. Thtrs, a relaiively small m o u n t  of fm can be to current diverted into said sensing circuir for switching 
snitched in core 30 by winding 34. The applicetion, to a first state; an interrogation winding coupled to said 
through switch 36 of a large current to windings 36 and sensing magnetic core; and one or more dux ampl i fyb  
40 will enable winding 40 lo  switch a greater amount of 55 circuit stzges connected to said sensi~g magnetic core in- 
fiux in core 32. The amount of fim and rapidity with terrogation winding. 
which ir is switched of course determines the amplitude 4. The combination of claim 3 .wherein each of said 
of the induced output signal. 
From the foregoing, it shouId be appreciated that a 
improved app.2ratus has been disclosed herein for sens- 
ing signals provided by magnetic memory cores when in- 
terrogated. By steering a signal applied to ah interroga- 
tion winding into a sense amplifying circuit connected in 
parallel therewith, and by constructing a sense amplifying 
circuit of cascaded stages, the complexity and expense of 
sezse amplifying circuits is considerably reduced. It is 
recognized however that a lime penalty is paid for the 
reduction in cost and coIliplexity inasmrrch as the signal 
gain introduced by the zrnpIifying circuits is developed 
sequentially or progressively in the cascaded stages. 
Althou~h each of the sense am~lifvinn s t a m  has becn 
flux ampliiying circuit stages incIudes a magnetic core 
having a i ~  interzqpation winding coupled thereto and 
wherein a drive winding mupled to the core in a scbse: 
quent stage is connected in parallel with each inlemm- 
tion winding. 
References @it& 
UNITED STATES PAT 
2,947,977 8/1950 Bloch ,-,,--,,,-,-,, 3 
3,041,582 6/1962 Cray ---,,,-,,,,,, 34 
3,125,743 3/1964 Pohm et al. -,-,,,,,, 34 
3,192,510 6/2965 Ffaherty ,,,,,,,,,,,, 34 
disclosed a s  being comprised. of ak&n&c &re with sig- STkI4LEY M. URWOWICZ, JR., Pr%mary Enami~cr, 


Digital memory sense amplifying means Patent

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