US3711839A

US3711839A - High density core memory matrix

Info

Publication number: US3711839A
Application number: US00165477A
Authority: US
Inventors: V Sell; S Alvi
Original assignee: Ampex Corp
Current assignee: Ampex Corp
Priority date: 1971-07-26
Filing date: 1971-07-26
Publication date: 1973-01-16
Anticipated expiration: 1990-01-16
Also published as: GB1347960A; JPS5648909B1; BE786689A; SE371709B; FR2147158A1; IT961652B; DE2236694A1; FR2147158B1; CA931659A; DE2236694B2

Abstract

A high density core memory matrix has cores spaced very close together along longitudinal axes and moderately close along latitudinal axes. The close longitudinal spacing is facilitated by orienting the cores at the maximum acute angle with respect to the longitudinal axis consistent with proper passage of the latitudinal drive lines. Undesirable electrical characteristics and propagation-time delays are minimized by passing the sense and inhibit lines along the extremely compacted longitudinal axis.

Description

United States Patent [1 1 Sell et al.

[ Jan. 16, 1973 [54] HIGH DENSITY CORE MEMORY MATRIX [75] Inventors: Victor L. Sell, Santa Monica; Syed M. S. Alvi, Placentia, both of Calif.

[73] Assignee: Ampex Corporation, Redwood City,

Calif.

[22] Filed: July 26, 1971 21 A pl. No.1 165,477

[52] US. Cl. ..340/l74 M, 340/174 AC, 340/174 CR [51] Int. Cl ..Gllc 5/02,Gllc5/06,Gllc 11/06 [58] Field of Search ...340/174 M, 174 MA, 174 VA,

340/174 CR, 174 BA [56] References Cited UNITED STATES PATENTS 3,085,314 4/l963 Lciching ..340/l 74 M OTHER PUBLICATIONS [BM Technical Disclosure Bulletin Vol. 3, No. 1-

June 1960, pg. 45.

IBM Technical Disclosure Bulletin Vol. 3, No. l0,

Mar. i961, pgs. 105-106.

Primary Examiner--James W. Moffitt Att0rney-Robert G. Clay [57] ABSTRACT A high density core memory matrix has cores spaced very close together along longitudinal axes and moderately close along latitudinal axes. The close longitudinal spacing is facilitated by orienting the cores at the maximum acute angle with respect to the longitudinal axis consistent with proper passage of the latitudinal drive lines. Undesirable electrical characteristics and propagation-time delays are minimized by passing the sense and inhibit lines along the extremely compacted longitudinal axis.

18 Claims, 2 Drawing Figures PATENTEDJANISIBB 4Y6; INVENTORS SYED H.S.ALVI VICTOR L. SELL ATTORNEYS HIGH DENSITY CORE MEMORY MATRIX BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to coincident current magnetic hibiting or separate wires for read half select and write half select on one or both axes. In the 2-wire, 2% D arrangements one of the half select lines is simultaneously used for sensing and no inhibit line is used.

Regardless of which core or wiring arrangement is used the cores are located on centers which are at least spaced one diameter apart in both the longitudinal and latitudinal directions. The cores are located at an angle of 45 to bisectthe angle between the longitudinal and latitudinal axes thus permitting diagonal threading of the sense lines to balance the partial excitation noise signals and obtain mutual cancellation.

SUMMARY OF THE INVENTION An improved high density core arrangement is attained by arranging a matrix of magnetic cores in a double herringbone pattern wherein two adjacent longitudinal rows of cores have the same orientation to form a similarly oriented pair of rows. Adjacent row pairs have opposite orientations. The cores are oriented at a nonbisecting acute angle greater than 45 with respect to the longitudinal axis and are greatly compacted, thereby permitting a sense line located along this longitudinal axis to be much shorter.

In one arrangement the cores are located on centers spaced approximately one-half diameter apart along the longitudinal axis and approximately one diameter apart along the latitudinal axis. The cores are oriented at an angle of 50 with respect to the longitudinal axis to accommodate this spacing.

This closely packed double herringbone arrangement provides many additional advantages. The bit density is doubled and the signal propagation time is greatly reduced. This is particularly important in large memory planes where it is desirable to have a constant access time regardless of core position. Additional advantages are gained from a decrease in the capacitance between the sense line and the drive lines and a decrease in the self inductance of the sense line. These factors, which are largely dependent upon the length of the sense and drive lines greatly decrease the amount of disturbance on the sense line as well as the amount of drive power that is required. Further, the close positioning of the cores along the longitudinal axes produces a tunneling or magnetic shielding effect. The spacing between cores is so small that the cores overlap and very little magnetic flux is able to escape the tunnel to couple with an adjacent row. Thus inductive coupling between wires in adjacent rows may be reduced as much as to 1.

Another advantage of the close spacing technique is manifested as the wires are threaded through the cores during manufacture. A needle is used to thread the various wires through the cores and it frequently happens that the needle point gouges or chips a piece of core material from one of the cores. This results in a defective core which must be replaced. However, as a result of the close spacing of the cores a needle is more closely constrained to the path through the core centers and needle damage is substantially reduced.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be had from a consideration of the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic representation of a portion of a core memory matrix arranged in accordance with the invention;

FIG. 2 is an enlarged, sectional view of a portion of the core memory matrix shown in FIG. 1, illustrating the preferred angle of orientation and spacing of magnetic cores.

DETAILED DESCRIPTION A high density core memory matrix in accordance with the invention utilizes a double herringbone pattern with cores positioned on centers less than one diameter apart and oriented at an acute angle greater than 45 with respect to longitudinal axes. The core spacing is particularly compressed along the longitudinal axes and the length of a sense line is minimized by running it parallel to the longitudinal axes. Such an arrangement provides substantial manufacturing and operating advantages.

As shown in FIG. 1, a high density core memory matrix in accordance with the invention has a substrate 12 with a matrix of magnetic cores 14 bonded thereto. The matrix in this example forms a memory plane having 16,384 cores with 128 cores in each row and each column. The example of FIG. 1 uses a 3-wire arrangement with an X or longitudinal drive line 16, a Y or latitudinal drive line 18 and a sense-inhibit line 20 inductively coupling each core. However, this high density technique is equally applicable to other wiring arrangements such as those having 2 or 4 wires coupling each core.

Although cores of any size may be used, in this example the cores 14 are standard sized 18 mil cores having an outside diameter of 0.0178-inches, an inside diameter of 0.01 17 inches and a width of 0.0042 inches. They are positioned in a double herringbone pattern in which two adjacent longitudinal rows of cores have a similar orientation to form a row pair and the cores of adjacent row pairs have opposite orientations. Minimal spacing along the longitudinal axis is attained by orienting the cores at the maximum angle consistent with threading of the latitudinal drive wire, 18 in this example. Furthermore, to obtain proper noise cancellation the core orientations may be reversed at selected intervals along each row pair and the sense-inhibit lines, which extend along the rows, may cross from one row in a row pair to the other. Thus, the cores in the lefthand portion of row pair X X which intersect column windings Y Y have an opposite orientation from those in the righthand portion which intersect column windings Y Y It will be appreciated that the number of core orientation reversals or sense-inhibit line crossovers can be increased if desired.

In addition to the longitudinal X drive lines a senseinhibit line 20 passes through each of the cores in the longitudinal direction. This sense-inhibit line 20 has two symmetrical halves labeled S-Ia and S-Ib which are connected at center tap 22. Each core in each row pair is coupled to one of the two halves of the sense-inhibit line 20 while the corresponding cores in the pairing row are inductively coupled to the other half. Thus each core in the matrix is inductively coupled to one of the two halves of the sense line. The symmetrical arrangement of the sense-inhibit line halves, together with the periodic reversal of the core orientations and sense-inhibit line crossovers results in a cancellation of noise disturbances when the switching of a core is being sensed.

The center tap 22 is connected to an inhibit wire 24 which in turn is connected by a switch 26 to a current sink or driver (not shown). During a read operation the sense-inhibit line 20 functions as a single balanced sense line with the switch 26 open and during a write operation the sense-inhibit line functions as two parallel inhibit lines with the switch 26 closed.

It will be appreciated by those skilled in the art that other patterns, spacings and orientations may be employed in accordance with the invention. For instance, similarly oriented groups of rows may contain four rather than two rows and different sizes of drive and sense wires may be used. The use of smaller latitudinal drive lines may permit a somewhat greater angle of orientation, thereby decreasing the threading aperture," but also enabling a closer spacing along the longitudinal axes.

Some important factors which affect the spacing of magnetic cores are illustrated in FIG. 2 which shows several cores 14 from the example shown in FIG. 1 at the intersection of the drive line pair X X with latitudinal drive lines Y Y and Y It can be seen that as the two drive wires and the sense-inhibit wire intersect at a core 14 the Y drive line passes between the X drive line and the sense-inhibit line. This affords a Y drive line an optimum aperture" as it passes through the cores in a column.

As shown in FIG. 1, the 18 mil cores 14 used in this example are located on center points which are spaced a distance A 0.0167 inch apart along the latitudinal axes between rows which are similar oriented and form a row pair. Between rows which are oppositely oriented the spacing is B 0.0181 inch. The longitudinal spacing between the center points is C 0.010 inch between cores which are similarly oriented and 0.0181 inch at the crossover point of the sense-inhibit line between drive lines Y. and Y In this example the X and Y lines have diameters of 0.0027 inch and the sense-inhibit line has a diameter of 0.0029 inch.

For 18 mil cores care must be taken when determining core spacing to maintain a clearance of about 0.0018 inch between cores and between cores and wires. Otherwise vibrational forces might cause destructive contacts which chip or otherwise damage the cores. Particularly critical are the distances between the outside diameters of adjacent cores and between a core and an adjacent Y drive line as illustrated in FIG. 2 by

distances

32 and 34 respectively.

As a result of the close core spacing of this arrangement the magnetic cores provide a tunneling or shielding effect which greatly reduces magnetic coupling between wires in adjacent rows. For instance, in trying to visualize vertical paths connecting drive line X with a portion of the sense-inhibit line in row X it can be seen that these vertical paths are substantially limited to the apertures through which the Y drive lines pass. This shielding reduces inductive coupling between rows by a factor of 10 or more.

The constraints which apply to the orientation of a magnetic core are illustrated in conjunction with the core which appears at the intersection of drive lines X and Y in FIG. 2. As shown therein the core is oriented at an angle a with respect to its longitudinal axis and has a vertical opening or aperture 40 with a width D for receiving drive line Y The core has an outside diameter D an inside diameter D,- and a width W.

From the standpoint of increasing core density along the longitudinal axis and decreasing the length of the sense-inhibit line it is desirable to orient the cores as nearly vertically as possible. This is illustrated by the spacing distance 34, as the core at the intersection of drive lines X and Y is rotated clockwise to a slightly more vertical orientation distance 34 increases. thus permitting a closer spacing. However, manufacturing considerations require that cores be able to receive a Y drive line without bending the line or the needle used to thread it. If there is not a straight path or aperture through a column of cores there will be needle damage as the cores are threaded. To provide adequate clearance the width D of the aperture 40 should be nearly double the diameter of the latitudinal drive line Y By extending the line of the lower edge of the inside diameter 42 of the core 14 to meet the righthand edge of the window 40, a right

triangle having vertices

44, 45, 46 is formed. It can be seen that the angle at vertex 45 is the angle at vertex 44 is 0 90 a and the angle at vertex 46 is a. It can be further seen from this arrangement that:

Applying this formula to the dimensions used in the example shown in FIG. 1 where W=0.0042, D,= 0.0117, and a 50, it can be determined that D 0.00428 inch. This is slightly less than twice the 0.0027 inch diameter of the drive line Y as required. In contrast, the 45 orientation for presently known arrangements would result in unnecessarily large windows and much less dense core spacings.

In addition to the advantages of increased bit density and decreased needle damage, there are substantial electrical advantages to be gained from arrangements in accordance with this inventiOn. The capacitive coupling between the parallel sense-inhibit and X drive lines is given the formula 1rE1 cash- (d/a) 4 where CAP capacitance, E permittivity of the dielectric between the two lines, 1 length of the parallel line in meters, d separation between the two lines in meters and a diameter of the wires in meters.

where N is the number of cores in a longitudinal, row, N,,,,, is the number of cores in a latitudinal column, A is the latitudinal spacing between core center points in similarly oriented rows, B is the latitudinal spacing between core center points in oppositely oriented rows, and C is the longitudinal spacing between cores. Because (N l) (C) is normally much greater than A+B the first portion of equation (5) predominates. Thus the length of the sense line is nearly proportional to C, the spacing between cores. For this reason the length of the sense line is nearly halved as compared with previously known double herringbone arrangements. As compared to previously. known arrangements using a diagonally oriented sense line the reduction in sense line length is even greater. The sense line length for these arrangements has an additional factor of V2 because it connects diagonali rather than adjacent cores. This results in a shortening of the sense line length by approximately 2 V2as com-; pared to diagonal sense lines. It can thus be seen from equation (4) that the present arrangement reducesi capacitive coupling by nearly 2 and 2 V2 over previ-i ously known arrangements.

Furthermore, signal delay, 7 is proportional to V L(CAP)l where L is the inductance of the line in hen ties/meter and equals [.L/IT cosh (d/a)1, and where p. is

i the permeability of the dielectric medium. For the arrangement of FIG. 1 as compared to a similar double herringbone pattern but with cores located on centers spaced one diameter apart, it has been shown that capacitance can be reduced by a factor of 2.75, in-. ductance by a factor of 1.46, and signal delay by a factor of 2.0.

Although there has been described above a specific arrangement of a high density core memory matrix in accordance with the invention for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention. What is claimed is: 1. A core memory comprising: a plurality of magnetic cores disposed along a lon-' gitudinal axis to form a row of cores similarly oriented at an acute angle substantially greater. than 45 with respect to the longitudinal axis, said cores being positioned about center points having a spacing between them less than the outside diameter of core;

means for selectively switching the magnetic state of a core; and

means for detecting the switching of a core.

2. The invention as set forth in claim 1 above, wherein said detecting means is a sense wire extending along the longitudinal axis and inductively coupling all; of the cores in the row.

3. The invention as set forth H6551 i above; wherein the center points have a spacing of substantially less than the outside diameter of a core along the longitudinal axis.

4. The invention as set forth in claim 1 above, wherein the cores have an outside diameter of approximately 0.018 inch and the center points have a spacing of approximately 0.010 inch along the longitudinal axis.

5. A core memory matrix comprising:

a plurality of magnetic cores having two stable states and arranged in rows along longitudinal axes and columns along latitudinal axes, each row having at least one group of a plurality of adjacent cores which are similarly oriented at an acute angle greater than 45 with respect to the longitudinal axis of the row and which are spaced about center points separated by substantially less than outside diameter of a core along the longitudinal axis of the row;

means for switching a selected core from one stable state to another; and

means for detecting the switching of a core.

6. The invention as set forth in claim 5 above, wherein the switching means includes a plurality of column drive lines, each inductively coupling all of the cores in a column and a plurality of row drive lines, each inductively coupling all of the cores in a row; and wherein the detecting means includes at least one. sense line positioned parallel to the row drive lines and inductively coupling at least a portion of the cores in at least one row.

7. A core memory matrix comprising a plurality of magnetic cores arranged in a double herringbone pattern having latitudinal and longitudinal axes, said cores being positioned about center points having a spacing of substantially less than an outside core diameter between them along the longitudinal axes.

8. The invention as set forth in claim 7 above, further comprising latitudinal drive means inductively coupling each core along a latitudinal axis, longitudinal drive means inductively coupling each core along a longitudinal axis and sense means inductively coupling at least a plurality of the cores along a longitudinal axis.

9. A magnetic core memory matrix comprising:

a plurality of cores having X and Y axis positions, each of said cores being disposed at an acute angle substantially greater than 45 with respect to the X axis; and

X and Y drive wires disposed orthogonally through said matrix with one X and Y wire coupling each different one of said cores, said cores having different spacings along the X and Y axes and having greater density along the X axis.

10. The invention as set forth in claim 9 above further including a sense wire disposed parallel to the X-axis and coupling said cores.

1 l. A high density core memory matrix comprising:

a substrate;

a plurality of magnetic cores positioned on the substrate in a double herringbone pattern with rows of cores defining longitudinal axes and columns of cores defining latitudinal axes, the cores being oriented at an acute angle greater than 45 with respect to the longitudinal axes and positioned about centers having a spacing of substantially less than the outside diameter of a core between them along the longitudinal axis;

latitudinal drive means inductively coupled to each core for providing each core in a selected column a partial select current;

longitudinal drive means inductively coupled to each core for providing each core in a selected row a partial select current, the combined column and row partial select currents being sufficient to.

switch a core common to the selected row and column; and

means for sensing the switching of a core.

12. The invention as set forth in claim 11 above, wherein said cores are positioned on centers spaced substantially one-half outside diameter apart along the longitudinal axes and one diameter apart along the latitudinal axes.

13. The invention as set forth in claim 12 above, wherein said cores are oriented at an angle of 50 and have an outside diameter of 0.0178 inch.

14. The invention as set forth in claim 11 above, wherein said latitudinal drive means comprises one wire for each column of cores having a diameter approximately D, wherein the cores have an inside diameter D, and a width W and wherein the approximate orientation angle, a, of the cores is defined by the equation w a? We a=8.lsm

W2 TH 15. A core memory comprising:

a plurality of magnetic cores disposed along a plurality of pairs of longitudinal axes to form row pairs, said cores being oriented at an acute angle substantially greater than 45 with respect to the longitudinal axes with all cores in a row pair being similarly oriented and cores in adjacent row pairs being oppositely oriented;

a plurality of longitudinal row drive lines, each extending along the longitudinal axis of one row and inductively coupling each core in the row;

a plurality of latitudinal drive lines extending perpendicular to the longitudinal drive lines, each inductively coupling at least one core in each row; and

' means extending along the longitudinal axis of at least one row and inductively coupling all of the cores in the row for selectively sensing and inhibiting the switching of inductively coupled cores.

16. A core memory plane comprising:

a substrate;

a plurality of magnetic cores disposed on one side of the substrate and arranged in rows defining longitudinal axes and columns defining latitudinal axes, each row having at least one group of cores similarly oriented at an acute angle substantially greater than 45 with respect to its longitudinal axis, the rows being grouped into pairs of adjacent rows having cores similarly oriented, the cores of adjacent pairs being oppositely oriented;

latitudinal drive means inductively coupling a half select current to all of the cores of a selected column;

longitudinal drive means inductively coupling a half select current to all of the cores of a selected row;

a sense line extending along the rows of cores and inductively coupling each core in the plane.

17. A core memory comprising: a plurality of magnetlc cores disposed along a longitudinal axis to form a row of cores similarly oriented at an acute angle greater than 47 with respect to the longitudinal axis, said cores being positioned about center points having a spacing between them less than the outside diameter of a core;

means for selectively switching the magnetic state of a core; and

means for detecting the switching of a core.

18. A core memory matrix comprising:

a plurality of magnetic cores having two stable states and arranged in rows along longitudinal axes and columns along latitudinal axes, each row having at least one group of a plurality of adjacent cores which are similarly oriented and which are spaced about center points separated by less than percent of the outside diameter of a core along the longitudinal axis of the row;

means for switching a selected core from one stable state to another; and

means for detecting the switching of a core.

Disclaimer 3,711,839.-V0t01" L. Sell, Santa Monica, and Syed M. 5. Alan, Placentia, Calif. HIGH DENSITY CORE MEMORY MATRIX. Patent dated J an. 16, 1973. Disclaimer filed Nov. 7 197 3, by the assignee, Ampew [Official Gazette Februawy 5, 1.974]

Claims

1. A core memory comprising: a plurality of magnetic cores disposed along a longitudinal axis to form a row of cores similarly oriented at an acute angle substantially greater than 45* with respect to the longitudinal axis, said cores being positioned about center points having a spacing between them less than the outside diameter of core; means for selectively switching the magnetic state of a core; and means for detecting the switching of a core.

2. The invention as set forth in claim 1 above, wherein said detecting means is a sense wire extending along the longitudinal axis and inductively coupling all of the cores in the row.

3. The invention as set forth in claim 1 above, wherein the center points have a spacing of substantially less than the outside diameter of a core along the longitudinal axis.

5. A core memory matrix comprising: a plurality of magnetic cores having two stable states and arranged in rows along longitudinal axes and columns along latitudinal axes, each row having at least one group of a plurality of adjacent cores which are similarly oriented at an acute angle greater than 45* with respect to the longitudinal axis of the row and which are spaced about center points separated by substantially less than outside diameter of a core along the longitudinal axis of the row; means for switching a selected core from one stable state to another; and means for detecting the switching of a core.

6. The invention as set forth in claim 5 above, wherein the switching means includes a plurality of column drive lines, each inductively coupling all of the cores in a column and a plurality of row drive lines, each inductively coupling all of the cores in a row; and wherein the detecting means includes at least one sense line positioned parallel to the row drive lines and inductively coupling at least a portion of the cores in at least one row.

9. A magnetic core memory matrix comprising: a plurality of cores having X and Y axis positions, each of said cores being disposed at an acute angle substantially greater than 45* with respect to the X axis; and X and Y drive wires disposed orthogonally through said matrix with one X and Y wire coupling each different one of said cores, said cores having different spacings along the X and Y axes and having greater density along the X axis.

11. A high density core memory matrix comprising: a substrate; a plurality of magnetic cores positioned on the substrate in a double herringbone pattern with rows of cores defining longitudinal axes and columns of cores defining latitudinal axes, the cores being oriented at an acute angle greater than 45* with respect to the longitudinal axes and positioned about centers having a spacing of substantially less than the outside diameter of a core between them along the longitudinal axis; latitudinal drive means inductively coupled to each core for providing each core in a selected column a partial select current; longitudinal drive means inductively coupled to each core for providing each core in a selected row a partial select current, the combined column and row partial select currents being sufficient to switch a core common to the selected row and column; and means for sensing the switching of a core.

13. The invention as set forth in claim 12 above, wherein said cores are oriented at an angle of 50* and have an outside diameter of 0.0178 inch.

14. The invention as set forth in claim 11 above, wherein said latitudinal drive means comprises one wire for each column of cores having a diameter approximately 1/2 D, wherein the cores have an inside diameter Di and a width W and wherein the approximate orientation angle, Alpha , of the cores is defined by the equation

15. A core memory comprising: a plurality of magnetic cores disposed along a plurality of pairs of longitudinal axes to form row pairs, said cores being oriented at an acute angle substantially greater than 45* with respect to the longitudinal axes with all cores in a row pair being similarly oriented and cores in adjacent row pairs being oppositely oriented; a plurality of longitudinal row drive lines, each extending along the longitudinal axis of one row and inductively coupling each core in the row; a plurality of latitudinal drive lines extending perpendicular to the longitudinal drive lines, each inductively coupling at least one core in each row; and means extending along the longitudinal axis of at least one row and inductively coupling all of the cores in the row for selectively sensing and inhibiting the switching of inductively coupled cores.

16. A core memory plane comprising: a substrate; a plurality of magnetic cores disposed on one side of the substrate and arranged in rows defining longitudinal axes and columns defining latitudinal axes, each row having at least one group of cores similarly oriented at an acute angle substantially greater than 45* with respect to its longitudinal axis, the rows being grouped into pairs of adjacent rows having cores similarly oriented, the cores of adjacent pairs being oppositely oriented; latitudinal drive means indUctively coupling a half select current to all of the cores of a selected column; longitudinal drive means inductively coupling a half select current to all of the cores of a selected row; a sense line extending along the rows of cores and inductively coupling each core in the plane.

17. A core memory comprising: a plurality of magnetic cores disposed along a longitudinal axis to form a row of cores similarly oriented at an acute angle greater than 47* with respect to the longitudinal axis, said cores being positioned about center points having a spacing between them less than the outside diameter of a core; means for selectively switching the magnetic state of a core; and means for detecting the switching of a core.

18. A core memory matrix comprising: a plurality of magnetic cores having two stable states and arranged in rows along longitudinal axes and columns along latitudinal axes, each row having at least one group of a plurality of adjacent cores which are similarly oriented and which are spaced about center points separated by less than 90 percent of the outside diameter of a core along the longitudinal axis of the row; means for switching a selected core from one stable state to another; and means for detecting the switching of a core.