Computer Package Cabinet And Module System

Abstract

The present invention relates in general to improved modular means for packaging electronic equipment and more particularly to the application of such packaging to the computer. The modular packaging means house a multiplicity of plug-in units, electrical connectors, associated wiring and cooling means and can be arranged in a system of abutting modular package means characterized (a) by the one sided access of each of the plug-in units and their appurtenances, (b) for their easy testing and replacement in the field from outside the package means and without disturbing the position of any of the modular package means, (c) for their space saving characteristics, (d) and by the flexibility of internal electrical connection of the plug-in units from plug-in unit to plug-in unit and from modular package to modular package.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to electronic packaging systems and more particularly to the modular packaging of high density printed circuit cards and other plug-in units and their appurtenances applicable to automatic data processing systems.

2. Description of the Prior Art

Under the impact of the computer explosion and the ever increasing density of electronic component packaging, with their concomittant complexity and economic considerations, a need has arisen for packaging which not only provides for the requisite component density but for system reliability and for ease of maintenance and serviceability in the field. Added to the increase in component density is a further requirement and trend toward greater miniaturization of electronic circuits and components in the nature of integrated circuits. When the above trends are considered in the light of increased computer usage in direct communication from customer terminal units to central processor units performing multiple processing operations simultaneously, it becomes obvious that the packaging means should allow for the expansion of the central processing system in modular steps as the number of users grow.

Under the influence of these expansive forces it becomes economically necessary that packaging systems have provisions for modular expansion of the computer system and that the accessibility and serviceability of each and every module and/or component be readily accessible for replacement in the field with an expenditure of a minimum of time and effort.

Some prior art packaging devices are illustrated in the patents of J.R. Pathmore U.S. Pat. 3,177,404 and H.S. Fall U.S. Pat. No. 2,987,364, which have modularized component construction which pull out in the form of a drawer. This class of devices however requires that successive drawers be pulled out, in order to test the system and replace components, with component becoming inaccessible when all the drawers are simultaneously pulled out.

A more recent class of packaging devices is illustrated in the following patents: L. Mayon et al., U.S. Pat. No. 3,146,047; C. J. Cressman et al., U.S. Pat. No. 3,147,403; R.G. Sinner, U.S. Pat. No. 3,147,404; and F. L. Williams, U.S. Pat. No. 3,188,525. This class of packaging devices is illustrative of the type wherein some components are mounted on swinging-gate arrangements and other components are mounted behind these gates, or in such manner that when more than one gate is swung out of the packaging enclosure some components become inaccessible from outside of the cabinet by virtue of their close proximity to one another. Furthermore, modular expansive systems with one sided accessibility to all components from outside the packaging system falls short of practical achievement in this class of devices because of the arrangement and operation of the components and pages/or gates. Moreover, the requirement of high packaging density necessitates the efficient removal of considerable amounts of heat generated by the electric components. Whereas, patent to C. J. Cressman et al. U.S. Pat. No. 3,147,403 shows a central air cooling system of the gates/pages in a computer system it can readily be appreciated that cooling is not uniform since the lower part of the pages receive air that is cooler than the top part of the pages. (The words "page" and "gate" are here used interchangeably in conformity to the usage of the several prior art patents disclosed.) Also, failure of the central cooling means can cause the system to become inoperative, whereas in the instant invention it is highly improbable that more than one cooling module will fail simultaneously.

Furthermore, the requirements of more efficient and functional use of the space where the modules are to be housed appears not to have been considered since no requirements as to dimensional ratios are disclosed that would allow for a building block structure that can grow in units of a module or multiples thereof, without waste of space.

OBJECTS

It is an object, therefore, of the instant invention to provide an improved low cost high density package and system with one sided exterior access to substantially all packaged components.

It is a further object of the instant invention to provide an improved page assembly with plug-in components mounted thereon having an improved decentralized forced air cooling system.

Still a further object of the present invention is to provide novel power distribution means throughout the system.

Still another object of the present invention is to provide a novel system arrangement of modular cabinets for multiple exterior surface to surface abutment arranged in a novel network providing one sided exterior access to the package component.

SUMMARY OF THE INVENTION

The above objects, and other objects which will become apparent to the reader, are achieved by providing a modular cabinet and system housing a plurality of plug-in units, printed circuit cards and their associated wiring and cabling, and an integral decentralized cooling system, said cabinet and system characterized (a) by the one sided accessibility of each of the packaged components for their testing and replacement in the field said testing and replacement being performed by personnel outside of the cabinet and system and without disturbing the position of any of the modular cabinets (b) by the internal electrical interconnection of the plug-in units within each modular cabinet from component to component and from modular cabinet to modular cabinet utilizing flat ribbon cable and (c) by a decentralized air cooling system capable of providing parallel multipaths for more efficient cooling of the components.

Modular box like cabinets of prescribed dimensional ratios for supporting and enclosing plug-in units for multiple exterior surface-to-surface abutment with similar cabinets are provided, each modular cabinet having a prescribed ratio of length to width of at least 2 and having a substantially flat top and bottom surface and four upright sides, three of the sides forming with the top and bottom surface an enclosure for enclosing the plug-in units and other appurtenant devices, and with the fourth side forming an opening with the top and bottom surfaces for access into the interior of the modular cabinet. At least two electrical equipment page frame assemblies, into which a plurality of plug-in units may be mounted, are hinged in the modular cabinet for radial motion about vertical axes into and out of the modular cabinet. Each frame is provided with a plurality of forced air-cooling devices that provide multiple paths of air flow over and about the components mounted in the page frame assembly and cabinet. A plurality of horizontal recessed electrical ducts are provided on each page frame assembly, communicating with a vertical recessed duct disposed on one end of the page frame assembly and extending vertically from top to bottom of the page frame assembly. Upper duct-means are also provided between the top of the cabinet and a horizontal partition in said cabinet. Interconnection between the components on the page assembly of a given cabinet, and also interconnection from cabinet to cabinet is accomplished by flat ribbon cable having a multiplicity of conductive wires embedded in a plastic non-conductive material, said cable being guided along said horizontal ducts into said vertical duct and thence to other similar ducts in other pages, and when necessary through the upper duct, formed by the top and a horizontal partition, into other cabinets.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an exploded view of a modular package including the cabinet assembly plug-in components and the page frame assembly.

FIG. 2 is an exploded view of a modular cabinet assembly.

FIG. 3 is a perspective view of a modular package assembly showing a plurality of forced air cooling units and the air flow paths to the modular package.

FIG. 4 is a perspective view of two page frame assemblies and hinging means.

FIG. 5 is a front elevation of a full back-board/or printed circuit card module.

FIG. 6 is a perspective view of a back-board module connector having a printed circuit board inserted therein.

FIG. 7 is a perspective view of several plug-in printed circuit card modules illustrating the flat ribbon cable distribution system.

FIG. 8 is a section C--C of FIG. 7 of a portion of the page frame assembly illustrating the electrical interconnection of printed circuit cards.

FIG. 9 is a modular cabinet abutting system illustrating a variety of arrangements having one sided access to the cabinets.

FIG. 10 is a perspective view illustrating various connectors and anchor devices of the invention.

FIG. 11 is a perspective view of the interface chassis cable transition from flat ribbon cable to round coaxial cable.

FIG. 12a is a perspective view showing a flat ribbon cable with its terminations and interconnector.

FIGS. 12b and 12c are schematic wiring diagrams of element 43 of FIG. 12a, and the ribbon cable.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Referring to FIGS. 1 and 2, there is shown an exploded view of a modular package assembly comprising a basic frame assembly 5 of the modular cabinet 500; the frame assembly 5 may be constructed of any structural material such as sheet steel or structural steel frame members such as U-bars, rods or beams. In a typical embodiment, the frame assembly comprises horizontal top and bottom support members 503 and 502 respectively that are spatially disposed in lateral, substantially parallel arrangement and are supported by upright vertical metal structural members 510 rigidly attached at the corners of the horizontal support members 503 and 502, and at additional positions where necessary, to provide structural rigidity as required. The upright structural members 510 protrude above the horizontal support member 503 and act as a support for a removable top dress panel 1. It can readily be appreciated that when dress panel 1 is in support position it forms together with horizontal support member 503 a passage-way or upper duct for housing auxiliary equipment and/or electrical wiring cables. Channelled integrally into the frame assembly 5 on either side are members 509 providing structural rigidity to the frame assembly. The vertical structural members 509 are recessed relative to the sides 501 so that side dress panels 4 and 8 are in flush engagement with structural frame members 510, and the edges of horizontal support members 503 and 502. The entire frame assembly 5 is generally fastened together by welding, although any other means of fastening may be utilized. When rear dress panel 2 and left door assemblies 6 and 7 respectively are placed in engaging position together with dress panel assemblies 1, 4 and 8 a cabinet 500 is formed that houses various electrical components and sub-components. Any or all of the dress panels are removable in order to form a modular system as shown in FIG. 9. For example, when side dress panels 4 and 8 are removed and other similar cabinets are abutted in side to side engagement it is readily appreciated that a top space or upper duct is formed between top dress panel 1 and horizontal support member 503 which has continuity of communication throughout the system with no obstructions between cabinet to cabinet and can be utilized as a large conduit carrying a variety of electrical cables for interconnecting to various modules of the system. Opening 504 on horizontal support member 503 serves as an access to this upper duct for communication between upper duct and the cabinet 500 housing the various components and sub-components. On the bottom horizontal support member 502 there is also an opening 505 which is generally utilized as an air intake for drawing air therethrough utilized for cooling the electrical components housed within the system.

Referring once again to FIG. 1, an exploded view of the various components and sub-components housed within the cabinet are seen. A plurality of page-frame assemblies 100 integrally supporting printed circuit module assemblies 21 and 22 (to be later described with FIG. 5) and cooling modules 23, are hinged onto top and bottom horizontal support members 503 and 502 respectively for circular motion into and out of the cabinet assembly. The page frame assembly 100 comprises typically a page frame 20 into which may be mounted a full printed circuit card module assembly 21 (also known as a backboard module) which is shown in greater detail in back elevation on FIG. 5. The full printed circuit card module 21 typically holds 108 printed circuit cards 32 which are inserted horizontally into printed circuit connectors 31 shown on FIG. 6, and FIG. 10; these connectors 31, have slots 310 on one face of the connector into which printed circuit cards 32 may be inserted and terminal pins 311 on the other face of the connector 310, again shown on FIG. 6. The printed circuit cards 32 horizontally mounted into the printed circuit connectors 31 are in turn combined into a module 21 comprising four vertical columns and 27 horizontal rows for a full module 21 which holds one hundred and eight printed circuit cards. The page frame assembly holds and supports three of these modules 21. Half-modules of printed circuit cards 22, may also be supported in the page frame 20.

A fan frame 24 is rigidly attached to one of the vertical sides of the page frame 20 and provides the structure for the mounting of fan modules 23, comprising a fan and housing, and utilized to direct air over the electrical components within the system for cooling purposes. Typically six fan modules 23 are mounted on the fan frame 24 and are operative to provide multiple cooling paths as shown on FIG. 3, when the page frame assembly is either within the cabinet or outside of the cabinet; furthermore, failure of one of the fan modules does not seriously impair the cooling functions of the remainder of the system. A vertical page frame cable race-way 15 is attached to the side opposite the side supporting the fan modules, and communicating together with upper, middle, and lower horizontal page cable race ways 16, 17, and 18 respectively, provide the flat cable passage way for the flat ribbon cable (to be later described), and forms a power distribution system shown in FIG. 7. Page frames air-baffles 12 and 13 are movably hinged on the front face of the page frame assembly 100 utilizing a hinge-plate 14 and may be opened or closed, gate-fashion, in order to obtain access to printed circuit boards. Top and bottom hinges 19 are rigidly attached to one end of the page frame 20 at the top and bottom of the page frame. The page frame assemblies 100 are then movably attached to the frame assembly 5 by means shown on FIG. 4 which operatively engage top and bottom hinges 19 for rotational motion into and out of the cabinet 500 about the lugs 409 on FIG. 4.

Mounted within the cabinet assembly 500 are typical plug-in units such as the power control assembly 9 which provides the facilities for turning the system power on and off, remote position maintenance panel units 11, and a column of power supplies 101. An AC input cord (not shown) enters the cabinet 500 through the base and connects to the power control assembly 9; the AC power is then distributed to the column of power supplies 101 which output DC power.

The completed page frame assemblies 100 are shown on FIG. 4 assembled and movably hinged by hinging means typically comprised of hinges 19 and pins 409 and further illustrate how the page frame assemblies are assembled for independent rotary motion about their hinging means. The page frame assemblies may be individually turned about vertical axes AA and BB like the pages of a book.

The vertical axes AA and BB are vertical projections through the center of the hinges 19. The hinges 19 are offset relative to each other to provide hinging the front page assembly (the one nearest the cabinet opening) near its back face (or face which is nearest the backside of the cabinet when the page frame is inside the cabinet); and to provide hinging the back page assembly near its front face or the face nearest the opening when the back page is inside the cabinet. This arrangement insures that the page frame assemblies will have a substantially parallel face to face spaced relationship when both page frame assemblies are totally within the modular cabinet, and will also be capable of independent angular motion in and out of the modular cabinet.

Furthermore the axes AA and BB are positioned, via their respective hinges, within the cabinet substantially between equal and opposite turning moments where one turning moment is formed by the product of the out-of-cabinet distance of the c.g. (center of gravity) of said page frame assemblies from said axes, and the c.g. of said page frame assemblies, and the other tuning moment is formed by the product of the c.g. of appurtenant apparatus from said axes, and the c.g. of said appurtenant apparatus so that when the page frame assemblies are rotated to be in a position substantially wholly outside the cabinet, the overturning moments formed by the page frame assemblies are counterbalanced by the opposite turning moments formed by the appurtenant apparatus.

The general air distribution system utilized for cooling the electrical components is shown in FIG. 3. Air is drawn into the cabinet through a filter opening 505 at the bottom of the cabinet and directed over the page-assembly printed-circuit cards 32 (FIG. 6) and the power supplies 101 (FIG. 1) by means of the individual cooling modules 23. The left front door 7 (FIG. 2) provides the final exhaust of the air through louvres 511 shown on FIGS. 1 and 2. It will be observed that the air flow travels across the short dimension of the page assembly in multiple paths; consequently, cooling is more efficient since the air in its path is traveling through a shorter distance of heat generating components than it would be if the airflow was directed vertically across the long dimension of the page frame. This provides cooler air for the last board in each row since the air passes over only four heat generating cards as opposed to a large number if the cards and cooling were oriented vertically. This provides for a cooler, more efficient and more trouble-free operation for the system when the page assembly is either within or outside of the cabinet 500.

The page cabling system is shown on FIG. 7, wherein a flat 43-conductor cable as shown on FIG. 12 A, is utilized to effect the electrical connections from page to page and from cabinet to cabinet. FIG. 8 on the other hand is a cross section C--C looking in toward a portion of a page assembly from the fan module end. Referring to FIG. 8, a three-slot flat cable connector, also shown on FIGS. 6 and 10, has three vertically spaced horizontal slots for receiving three full-size circuit boards one of which 32 is shown on FIGS. 6 and 8, or three foreshortened circuit boards, a typical one 310 shown on FIGS. 8 and 10 together with rear edge connector 30, also shown on FIGS. 8 and 10, or the connector 31, may receive six cable connectors 40 some of which are shown on FIG. 10. On the other face of the flat cable slot connector 31 are the pin connectors 311. Upper, middle and lower horizontal cable raceways 16, 17, and 18 (FIG. 8) respectively are provided spanning the full width of the page frame-assembly at horizontal locations 120, 130, and 140 respectively. As seen in FIG. 8 the lower horizontal raceway 18 houses the short inter module jumper cables. The middle raceway 17 collects all cables from modules below and above. The upper raceway is a cover used to contain the cables 17 the middle raceway. The flat ribbon cable collected in the horizontal cable raceways at positions 120, 130, and 140 are routed horizontally into the vertical page cable raceways 15 where they are routed vertically up and down the edge of the page for routing to other modules as shown on position 150. The general routing of the cables then is from the rear edge connector on a printed circuit board through the horizontal page raceways to the vertical page raceways and onto other horizontal upper ducts on the top portion of the cabinet for interconnection with other cabinets or for connection to the outside world.

The use of flat ribbon cable as shown on FIG. 12A allows the packaging of this cabinet assembly in a way that no other cabling could have done because of its compactness and flat arrangement. The standard flat ribbon cable 42 is a flat 43-conductor cable, terminating in a printed wiring board 40 with fourteen signals and 29 ground wires. The cable itself comprises 43 single conductor wires that are bonded and embedded in a plastic material such as Teflon..sup.1 (.sup.1. Teflon - A trademark of E. I. dePont deNemours & Company) A cable protective hood 41 forms a protective shroud around the printed circuit board connection 40. For interconnecting or linking one flat cable connector with another flat cable connector, a feed through connector 43 is provided. The schematic of the feed through connector 43 is shown on FIGS. 12B and 12C. Note that wires embedded on face A1 are cross connected through the feed-through or link connector 43 to form a continuous circuit with wires embedded in face A2, and similarily for wires embedded in face B1 and B2. The reason for this is that the cable is usually bent U-shape along the arrow D shown on FIG. 12B in order to interconnect printed-circuit cards located in different rows. In this U-shape position, it will be noted that the left leg of the U as shown on FIG. 12C has wire A1 to the left of wire B1; also in the right leg of the U, wire A2 which is a continuation of wire A1, is also to the left of wire B2 which is a continuation of wire B1; therefore relative positions for inserting the flat ribbon cable connector into a printed circuit board and connector can always be identified. Without the cross over feature, great confusion results when interconnecting units in different rows because the positions of the wires are altered in the different legs, unless a cross-over link connection is provided. This cross over feature permits the color coding of face A1 with one color, such as for example red, and the color coding of the face B1, with another color such as for example black, and specifying the insertion of the connector into its slot with a given color always in the same position irrespective of which end, left or right, of the cable is plugged into the slot connector. i.e., specifying the connector 41 is always to be inserted into the slot connector with the red side up or to the left as the case may be.

The termination 40 of the flat cable 42 of FIG. 12A can also insert into a feed-through or back-link connector 43, or it may insert into the slots 310 of a flat cable connector 31 of FIG. 10, or it can insert into the slot of rear edge connector 30 also shown in FIG. 10. To retain the flat cable connector 40 firmly within the rear edge connectors 30, or within the flat cable-connector 31, a resilient cable-connector retainer 44 is forced-fitted into the connector slots 310, which retainer may be deflected up and down to provide insertion of the flat cable-connector into the slots 310, and retention of the cable connector firmly within the slot in its normal non-deflected position.

At the end of a line of cabinets the flat ribbon cable enters a bulk head 49, FIG. 11. It is through this bulk head 49 that the internal connections which is accomplished by a flat ribbon cable must be transformed into "Underwriter Laboratory Approved" coaxial cable for connecting equipment external to the system. The bulk head 49 has cut-outs which provide for the attachment of cable transformation assembly 103. The cable transformation assembly 103 is comprised of a printed circuit connector 45, with its protective cover 46 surrounding the external cable 47 which is electrically connected to the printed circuit connector 45. A flat cable cap 48 adapts the small size of the flat cable connector assembly 41 and 49 to the relatively large size of the external connector assembly 103.

The individual cabinets 500 heretofore described may be arranged into a large system of cabinets housing electrical components, subcomponents and printed circuit card modules as shown on FIG. 9. Many combinations and sub-combinations are possible. In FIG. 9, for example the cabinets have a left side L, a right side R, a front side F and a back side B; when facing the front side and looking toward the back side then the following abutting sub-combinations are possible for one sided access to the system:

1. L and R,

2. b and B,

3. l and B,

4. r and B.

The dotted lines further illustrate the compact "squared-off" arrangement possible with further module additions.

It will be apparent from the foregoing disclosure of the invention that numerous modifications, changes and equivalents will now occur to those skilled in the art. All of which fall in the true spirit and scope contemplated by the invention.

Claims

What is claimed is:

1. A modular cabinet for supporting and enclosing plug-in units, said cabinet capable of one sided access to the plug-in units from the exterior of the cabinet and said cabinet also capable of multiple exterior surface to surface abutment in a prescribed manner with similar cabinets comprising in combination:

a. a modular cabinet having a prescribed ratio of length to width of at least 2 and having a substantially flat top and bottom surface and three upright side surfaces, forming with the top and bottom surface an enclosure for enclosing the plug-in units, the fourth side position being unenclosed and forming an opening with the top and bottom surfaces for access into the interior of said modular cabinets;

b. at least two electrical equipment page frame assemblies into which a plurality of plug-in units may be inserted;

c. a plurality of discrete individually powered self-contained cooling fans rigidly attached to said electrical equipment page frame assemblies for cooling the plug-in units when they are inserted in said page frame assemblies;

d. and a plurality of fixed hinging means independently hinging said electrical equipment page frame assemblies in said modular cabinet for independent angular movement about vertical axes of one of said page frame assemblies relative to the other of said page frame assemblies on said hinging means into and out of said modular cabinet.

2. A modular cabinet as recited in claim 1 including appurtenant apparatus and wherein the axis of one set of said hinging means is offset relative to the axis of another set and said page frame assemblies are rotationally mounted on said offset hinging means for independent relative motion into and out of said cabinet, and said page frame assemblies have the back face of one page frame assembly in substantially parallel spaced relationship with the front face of another page frame assembly when said page frame assemblies are substantially within said cabinet.

3. A modular cabinet as recited in claim 2 including means for providing stability to said modular cabinet when said page frame assemblies are rotated to a position substantially outside said modular cabinet.

4. A modular cabinet as recited in claim 2 wherein said hinging means are positioned within said modular cabinet substantially between equal and opposite turning moments where one turning moment is formed by the product of the out-of-cabinet distance of the c.g. (center of gravity) of said page frame assemblies from said axes, and the c.g. of said page frame assemblies, and the other turning moment is formed by the product of the distance of the c.g. of appurtenant apparatus from said axes, and the c.g. of said appurtenant apparatus.

5. A modular cabinet as recited in claim 2 wherein said appurtenant apparatus comprise power supplies, structural frame assemblies, and electrical cabling.

6. A modular cabinet for supporting and enclosing plug-in units, said cabinet capable of one sided access to the plug-in units from the exterior of the cabinet and said cabinet also capable of multiple exterior surface to surface abutment in a prescribed manner with similar cabinets comprising in combination:

a. a modular cabinet having a prescribed ratio of length to width of at least 2 and having a substantially flat top and bottom surface and three upright side surfaces, forming with the top and bottom surface an enclosure for enclosing the plug-in units, the fourth side position being unenclosed and forming an opening with the top and bottom surfaces for access into the interior of said modular cabinet;

b. at least two electrical equipment page frame assemblies into which a plurality of plug-in units may be inserted;

c. a plurality of cooling means rigidly attached to said electrical equipment page frame assemblies for cooling the plug-in units when they are inserted in said page frame assembly, said plurality of cooling means comprising self contained power fan modules rigidly attached to one of the long edges of said page frame assemblies and having the fan outlets perpendicular to said long edges for forcing multiple paths of air to travel parallel to the short edges of said page frame assemblies;

d. and a plurality of hinging means hinging said electrical equipment page frame assemblies in said modular cabinet for independent angular movement of one of said page frame assemblies relative to the other of said page frame assemblies on said hinging means into and out of said modular cabinet.

7. A system of at least two abutting modular box-like cabinets, each cabinet enclosing a plurality of modular sub-units, said system characterized by the one sided accessibility of each of the modular sub-units for their testing or re-placement, in the field, without disturbing the position of any of the modular box-like cabinets comprising:

a. a plurality of modular rectangular box-like cabinets of uniform height each of said modular cabinets having a ratio of length to width of 2 and having a substantially flat top and bottom surface and four upright sides designated F, B, L and R with sides F and B being the front and back sides respectively, and sides L and R being the left and right sides respectively;

b. the sides B, L and R forming with a top and bottom surface an enclosure for supporting and enclosing the modular sub-units and with side F forming an access opening to the interior of said box-like structure, said access opening being protected by at least one door;

c. said plurality of modular box-like cabinets being arranged into an abutting system wherein a side of one cabinet abuts a side of another cabinet in accordance with the following pattern;

B with B,

and wherein the L side of one B and B pattern abuts the R side of another B and B pattern and wherein said system of abutting cabinets has a rectangular shape having a length l and a width w and wherein l is substantially an even multiple of w.

8. A system of at least two abutting modular box-like cabinets, each cabinet enclosing a multiplicity of modular sub-units, said system characterized by the one sided accessibility of each of the modular sub-units for testing or replacement, in the field, without disturbing the position of any of the modular cabinets comprising in combination:

a. a plurality of rectangular modular box-like cabinets of uniform height each of said modular cabinets having a prescribed ratio of length to width and having a substantially flat top and bottom surface and four upright sides F, B, L and R with sides F and B being the front and back sides respective, and sides L and R being the right sides respective;

b. the sides B, L and R forming with the top and bottom surface an enclosure for supporting and enclosing the modular sub-units and with side F forming an access opening to the interior of said box-like structure, said access opening being protected by at least one access door;

c. said plurality of modular box-like cabinets being arranged into a system of abutting modular cabinets wherein a side of one cabinet abuts a side of another cabinet in surface-to-surface contact and such that the boundaries of the surface of the side of one cabinet substantially align and make contact with the boundaries of the surface of the side of another cabinet, and wherein said abutting system assumes the following pattern;

B of one cabinet with B of another cabinet making a B and B combination,

and wherein the L side of one B and B combination abuts the R side of another B and B combination and wherein said system of abutting cabinets has a substantially rectangular shape having a length l and a width w and wherein l is substantially an odd multiple of w.

9. A system of at least three abutting modular box-like cabinets, each cabinet enclosing a plurality of modular subunits, said system characterized by the one sided accessibility of each of the modular sub-units for their testing or replacement, in the field, without disturbing the position of any of the modular cabinets comprising in combination:

a. a plurality of substantially rectangular modular box-like cabinets of uniform height each of said modular cabinets having a prescribed ratio of length to width of 2 and having a substantially flat top and bottom surface and four upright sides F, B, L and R, with sides F and B being the front and back sides respective, and sides L and R being the left and right sides respectively;

b. the sides B, L and R forming with the top and bottom surface an enclosure for supporting and enclosing the modular sub-units and with side F forming an access opening to the interior of said box-like structure, said access opening being protected by at least one access door;

c. said plurality of modular box-like cabinets arranged into a substantially rectangular system of abutting modular cabinets wherein at least a first and a second cabinet are aligned in back-to-back surface contact with each other and wherein a third cabinet has its back surface in aligned surface-to-surface contact with a side surface of each of said first and second cabinets, and wherein said aligned abutting surface contacts assume the following pattern;

B of the third cabinet with L of the first cabinet and R of the second cabinet.

10. A system of at least three abutting modular box-like cabinets, each cabinet enclosing a plurality of modular sub-units, said system characterized by the one sided accessibility of each of the modular sub-units for the testing or replacement, in the field, without disturbing the position of any of the modular cabinets comprising in combination:

a. a plurality of substantially rectangular modular box-like cabinets of uniform height, each of said modular cabinets having a prescribed ratio of length to width of 2 and having substantially flat top and bottom surfaces and four upright sides F, B, L and R, with sides F and B being the front and back sides respective, and sides L and R being the left and right sides respectively;

b. the sides B, L and R forming with the top and bottom surface an enclosure for supporting and enclosing the modular sub-units and with side F forming an access opening to the interior of said box-like structure, said access opening being protected by at least one access door;

c. said plurality of modular box-like cabinets arranged into a substantially rectangular system of abutting modular cabinets wherein at least a first and second cabinet are aligned in back-to-back surface contact with each other and wherein a third cabinet has its back surface in aligned surface-to-surface contact with the side surface of each of said first and second cabinets, and wherein said aligned abutting surface contacts assume the following pattern;

B of the third cabinet with R of the first cabinet and L of the second cabinet.