WO2003043005A1

WO2003043005A1 - Coded single reel magnetic tape cartridge

Info

Publication number: WO2003043005A1
Application number: PCT/US2001/043678
Authority: WO
Inventors: William J. Vanderheyden; David Thomas Hoge
Original assignee: Quantum Corporation
Priority date: 2001-11-09
Filing date: 2001-11-09
Publication date: 2003-05-22

Abstract

The present coded magnetic tape cartridge which functions to control the compatibility of the magnetic tape cartridge with a plurality of existing tape drives, some of which are compatible in a transparent manner and others which are compatible in a way that mimic other magnetic tape cartridges. Thus, the present coded magnetic tape cartridge can be loaded into a new generation SDLT tape drive, is compatible with selected old generation tape drives, where the old generation tape drives can take advantage of additional features of the enclosed tape media, but the SDLT tape drive does not mistake this magnetic tape cartridge as an SDLT magnetic tape cartridge.

Description

CODED SINGLE REEL MAGNETIC TAPE CARTRIDGE

Field of the Invention

This invention relates to single reel magnetic tape cartridges and to a method of coding tape cartridges to enable the tape cartridge to be used only in a selected plurality of tape drives.

Problem It is a problem in the field of single reel magnetic tape cartridges to ensure that the magnetic tape cartridge is used in a tape drive that is equipped to handle the media that is stored in the magnetic tape cartridge.

Magnetic tape cartridges are configured to meet certain physical requirements for use in a particular type of tape drive. These tape cartridges are said to have a particular form factor, which is the definition of the peripheral dimensions of the magnetic tape cartridge and the characteristics of the physical interface with the tape drive. It is often desirable to produce a magnetic tape cartridge that has the same form factor as existing magnetic tape cartridges, but has other characteristics that are unique to another tape drive. For example, the length and type of magnetic tape stored on the magnetic tape cartridge may vary, and/or the recording characteristics of the data written on the magnetic tape may vary. If the dimensional and recording characteristics of the magnetic tape differ, this magnetic tape cartridge must be distinguishable from existing magnetic tape cartridges having the same form factor, to enable the tape drives to properly interface with this magnetic tape cartridge.

Modifications in the magnetic tape cartridges have been utilized to prevent one type of magnetic tape cartridge from being used in conjunction with an incompatible tape drive. One such magnetic tape cartridge lockout apparatus described by Johnson, et al., (U.S. Patent No. 6,270,030) provides a tab projecting from a surface of the magnetic tape cartridge housing to prevent insertion of the magnetic tape cartridge into an incompatible tape drive. The tab is positioned to contact the door actuator surface of old models of tape drives but to be compatible with new models of tape drives by defining a cross-sectional area perpendicular to the insertion direction that is smaller than the gap formed in the door actuator of new models of tape drives to permit this magnetic tape cartridge to be inserted only in the new tape drives. Magnetic tape cartridges with the mechanical lockout apparatus just described can only be used with new tape drives. In other words, the new magnetic^" tape cartridge is not backward compatible with existing tape drives. However, while this magnetic tape cartridge type lockout apparatus provides a method for a new generation tape drive to take advantage of new tape media contained in a magnetic tape cartridge, it fails to provide a magnetic tape cartridge that is compatible for use with old generation tape drives, where though these old generation tape drives may not be able to use the new tape media but would not be harmed by the loading of this new tape media.

Another type of magnetic tape cartridge, termed the SDLT Magnetic Tape Cartridge, includes a lockout rib formed in the recess of the side face of the housing, where the lockout rib projects distally from the recess and extends along the length of the recess in the magnetic tape cartridge insertion direction. The lockout rib is positioned to prevent insertion of the magnetic tape cartridge into an incompatible tape drive, yet fit in a slot formed in the door actuator of a corresponding SDLT tape drive. This SDLT magnetic tape cartridge is therefore compatible with the above- noted Johnson tape drives but not old generation tape drives. In addition, the SDLT tape drive is equipped with a sensor, located in the slot, for detecting the presence of the rib formed on the SDLT magnetic tape cartridge. This enables the SDLT tape drive to receive the old magnetic tape cartridges, the SDLT magnetic tape cartridges, but not the Johnson magnetic tape cartridges. This sensor mechanism provides a way of distinguishing between the old magnetic tape cartridges and the SDLT magnetic tape cartridge. However, the Johnson magnetic tape cartridge is incompatible with the SDLT tape drive, due to the lockout tab of the Johnson magnetic tape cartridge being of a size to prevent its insertion into the slot formed in the SDLT tape drive. This limits the selection of magnetic tape cartridges that can be used in the SDLT tape drive.

For these reasons, a need exists for a new tape media identification for a magnetic tape cartridge that can be loaded into a new generation SDLT tape drive, is compatible with selected old generation tape drives, where the old generation tape drives can take advantage of additional features of the enclosed tape media, but the SDLT tape drive does not mistake this magnetic tape cartridge as an SDLT magnetic tape cartridge.

Solution The above described problems are solved and a technical advance achieved in the field by the present coded magnetic tape cartridge which functions to control the compatibility of the magnetic tape cartridge with a plurality of existing tape drives, some of which are compatible in a transparent manner and others which are compatible in a way that mimic other magnetic tape cartridges. Thus, the present coded magnetic tape cartridge can be loaded into a new generation SDLT tape drive, is compatible with selected old generation tape drives, where the old generation tape drives can take advantage of additional features of the enclosed tape media, but the SDLT tape drive does not mistake this magnetic tape cartridge as an SDLT magnetic tape cartridge.

The coded magnetic tape cartridge of the present invention is architected to be compatible with both the Johnson (second tape drive) and the SDLT (third tape drive) tape drives, but appears to the SDLT tape drive as an old generation (first) magnetic tape cartridge, since it does not activate the sensor. This is accomplished by forming a coding fin in the recess in the side face of the magnetic tape cartridge housing, aligned to be parallel to the insertion direction, positioned to fit in the gap of the Johnson tape drive and the slot of the SDLT tape drive, but of length to fail to activate the sensor of the SDLT tape drive. Therefore, this coded magnetic tape cartridge can be used in the SDLT tape drive, but the SDLT tape drive does not sense the presence of a rib and presumes it is an old generation magnetic tape cartridge. This enables this magnetic tape cartridge to be compatible with both the Johnson and SDLT tape drives, but to appear to be an old generation magnetic tape cartridge to the SDLT tape drive.

Brief Description of the Drawings Figure 1 illustrates in block diagram form the overall architecture of a typical tape drive; Figure 2 illustrates a perspective view of a prior art old generation magnetic tape cartridge;

Figure 3 illustrates a perspective view of a prior art old generation tape drive receiver;

Figure 4 illustrates a perspective view of a prior art Johnson magnetic tape cartridge;

Figure 5 illustrates a perspective view of a prior art Johnson tape drive receiver;

Figure 6 illustrates a perspective view of a prior art SDLT magnetic tape cartridge; Figure 7 illustrates a perspective view of a prior art SDLT tape drive receiver; Figure 8 illustrates a schematic illustration of the door actuator assembly of Figure 3;

Figure 9 illustrates a schematic illustration of the door actuator assembly of Figure 5;

Figure 10 illustrates a schematic illustration of the door actuator assembly of Figure 7;

Figure 11 illustrates a perspective view of the present coded magnetic tape cartridge; and Figure 12 illustrates a schematic illustration of the door actuator assembly of

Figure 7, used with the present coded magnetic tape cartridge.

Detailed Description

Figure 1 illustrates in block diagram form the overall architecture of a typical tape drive 10 that is used to read and write data from the magnetic tape 20 that is loaded in a single reel magnetic tape cartridge 22. The tape drive 10 includes a read/write head 12, a take-up reel 14 driven by a take-up reel motor 15, and a tape cartridge receiver 16. The magnetic tape 20 is loaded in the magnetic tape cartridge

22 that is loaded into the tape cartridge receiver 16. The tape cartridge receiver 16 includes a supply drive motor 25 that engages and drives the supply reel 24 when the magnetic tape cartridge 22 is loaded into the tape cartridge receiver 16. A buckling mechanism is used by the tape drive 10 to attach to magnetic tape 20 to draw the magnetic tape 20 from the magnetic tape cartridge 22 though a tape path. in the tape drive 10 and wound on the take-up reel 14.

The standard form factor of the magnetic tape cartridge includes a housing that encloses a single reel on which is stored a length of magnetic tape and optionally a length of cleaning tape. The magnetic tape cartridge housing has an access door extending across a portion of the front face thereof, and is equipped with a recess along a portion of a side face, with a door latch mounted on a pivot axis that is positioned at the juncture of the front face and the recess. The tape drives all have a door actuator assembly positioned in a cartridge interface, termed a '•'receiver". Each of the door actuator assemblies includes a ramp to unlock the access door latch on the magnetic tape cartridge, and an access door actuator surface top open the access doors as the magnetic tape cartridge is inserted into the tape drive along an insertion direction. There are a plurality of types of magnetic tape cartridges of substantially identical form factor that are used with this type of tape drive, with each successive magnetic tape cartridge being reverse compatible with all of the older generation tape drives, in a manner that the tape drive is unaware of the type of magnetic tape cartridge that is inserted therein. Thus, newer generations of tape drives can use all prior and existing magnetic tape cartridges, but new magnetic tape cartridges are incompatible with older generation tape drives and therefore must include a lockout mechanism to prevent the use of these magnetic tape cartridges therein.

The access door actuator assembly on the Johnson tape drive, noted above, is equipped with a gap extending along the insertion direction and between the ramp and the door actuator assembly. The corresponding Johnson (second) magnetic tape cartridge includes a tab formed in the recess of the side face of the housing, where the tab projects distally from the recess. The tab is positioned to contact the door actuator surface of the old generation tape drive by defining a cross-sectional area perpendicular to the insertion direction where the tab is also smaller than the gap formed in the Johnson tape drive to permit the Johnson magnetic tape cartridge to be inserted only in the Johnson tape drive.

The access door actuator assembly on the SDLT tape drive, noted above, is equipped with a slot extending along the insertion direction and between the ramp and the door actuator assembly, which slot is smaller in dimension than the gap on the Johnson tap drive. The corresponding SDLT (third) magnetic tape cartridge includes a rib formed in the recess of the side face of the housing, where the rib projects distally from the recess. The rib is positioned to contact the door actuator surface of the old generation tape drive by defining a cross-sectional area perpendicular to the insertion direction that is smaller than the gap formed in the Johnson tape drive and of a size to fit in the slot of the SDLT tape drive, to permit the SDLT magnetic tape cartridge to be inserted in the Johnson and SDLT tape drives, while the old generation (first) magnetic tape cartridge is compatible with the old generation, Johnson, and SDLT tape drives and the Johnson magnetic tape cartridge is only compatible with the Johnson tape drive. In addition, the SDLT tape drive is equipped with a sensor, located in the slot, for detecting the presence of the rib formed on the corresponding SDLT magnetic tape cartridge. This enables the SDLT tape drive to receive both the old generation magnetic tape cartridges and the SDLT magnetic tape cartridges, but also provides a way of identifying the particular type of magnetic tape cartridge that is inserted into the SDLT tape drive. However, the Johnson magnetic tape cartridge is incompatible with the SDLT tape drive, due to the tab being of a size to prevent its insertion into the slot formed in the SDLT tape drive. Figure 2 illustrates a perspective view of a prior art old generation magnetic tape cartridge 30 while Figure 3 illustrates a perspective view of a prior art old generation tape drive receiver 50 for a old generation tape drive 80. The old generation magnetic tape cartridge 30 consists of a housing 32 that encloses a single reel on which is wound a predetermined length of magnetic tape. The housing 32 is manufactured from molded plastic and includes an access door 34 that rotates about an axis 36 in the direction 38 when the old generation magnetic tape cartridge 30 is inserted into the old generation tape drive receiver 50. The access door 34 includes a door latch 40 having a cut out 42. Side surface 44 of the old generation magnetic tape cartridge 30 includes a recess 46 that cooperatively engages with the old generation access door actuator assembly 48 located in the old generation tape drive receiver 50.

To load the old generation magnetic tape cartridge 30 in the old generation tape drive 80, the front face 58 of the old generation magnetic tape cartridge 30 is inserted into the old generation tape drive receiver 50 along an insertion direction 58. Side guide surface 60 and top guide surface 62 of the old generation tape drive receiver 50 engage with side surface 44 and top surface 64 of the old generation magnetic tape cartridge 40, respectively. As the old generation magnetic tape cartridge 30 progresses along the insertion direction 58, ramp 70 penetrates cutout 42. Further insertion of the old generation magnetic tape cartridge 30 causes the ramp 70 to lift the door latch 40. Surface 72 of the access door 34 engages with the door actuator surface 74 of the old generation tape drive receiver 50 to rotate the access door 34 in direction 38, thereby exposing the magnetic tape stored in the housing 32.

Figure 4 illustrates a perspective view of a prior art Johnson magnetic tape cartridge 130 while Figure 5 illustrates a perspective view of a prior art Johnson tape drive receiver 150 for a old generation tape drive 180. Housing 132 includes an access door 134 that rotates about an axis 136 in the direction 138 when the Johnson magnetic tape cartridge 130 is inserted into the Johnson tape drive receiver 150. The access door 134 includes a door latch 140 having a cut out 142. Side surface 144 of the Johnson magnetic tape cartridge 130 includes a recess 146 that cooperatively engages with the Johnson access door actuator assembly 148 in the Johnson tape drive receiver 150. The Johnson magnetic tape cartridge 130 has substantially the same form factor as the old generation magnetic tape cartridge 30, except that the recess 146 includes a tab 110. The tab 110 may be integrally formed with the recess 146 or attached thereto with an adhesive. The Johnson tape drive receiver 150 includes an access door actuator assembly 148 having a ramp 170 and a door actuator surface 174. A gap 112 is formed between ramp 170 and the door actuator surface 174 to enable the tab 110 to pass through this gap 112. The tab 110 is positioned to contact the door actuator surface 74 of the old generation tape drive 80 by defining a cross-sectional area perpendicular to the insertion direction 58 that is smaller than the gap 112 formed in the Johnson tape drive 180 between ramp 170 and the door actuator surface 174 to permit the Johnson magnetic tape cartridge 130 to be inserted only in the Johnson tape drive 180, whereby the Johnson magnetic tape cartridge 130 is only compatible with the Johnson tape drive 180 while the old generation magnetic tape cartridge 30 is compatible with both the old generation 80 and the Johnson 180 tape drives.

Figure 6 illustrates a perspective view of a prior art SDLT magnetic tape cartridge 230 while Figure 7 illustrates a perspective view of a prior art SDLT tape drive receiver 250 for a SDLT tape drive 280. Housing 232 includes an access door 234 that rotates about an axis 236 in the direction 238 when the SDLT magnetic tape cartridge 230 is inserted into the SDLT tape drive receiver 250. The access door 234 includes a door latch 240 having a cut out 242. Side surface 244 of the SDLT magnetic tape cartridge 230 includes a recess 246 that cooperatively engages with the SDLT access door actuator assembly 248 in the SDLT tape drive receiver 250. The SDLT magnetic tape cartridge 230 has substantially the same form factor as the old generation magnetic tape cartridge 30 and the Johnson magnetic tape cartridge 130, except that the recess 246 includes a longitudinal rib 210. The rib 210 may be integrally formed with the recess 246 or attached thereto with an adhesive. The SDLT tape drive receiver 250 includes an access door actuator assembly 248 having a ramp 270 and a door actuator surface 274. A slot 212 is formed between ramp 270 and the door actuator surface 274 to enable the rib 210 to pass through this slot 212.

Figure 8 illustrates a schematic illustration of the door actuator assembly 48 of Figure 3, Figure 9 illustrates a schematic illustration of the door actuator assembly 148 of Figure 5, and Figure 10 illustrates a schematic illustration of the door actuator assembly 248 of Figure 7. Johnson magnetic tape cartridge 130 is shown in Figure 8 engaging the door actuator assembly 48 of Figure 3. As the Johnson magnetic tape cartridge 130 slides along the old generation tape drive receiver 50, the tab 110 engages the door actuator surface 74 to block complete insertion of the Johnson magnetic tape cartridge 130 into the old generation tape drive 80. Therefore, the Johnson tape cartridge cannot be used with the old generation tape drive 80. Johnson magnetic tape cartridge 130 is shown in Figure 9 engaging the door actuator assembly 148 of Figure 5. As the Johnson magnetic tape cartridge 130 slides along the Johnson tape drive receiver 150, the tab 110 passes through the gap 112 between the ramp 170 and the door actuator surface 174 to enable complete insertion of the Johnson magnetic tape cartridge 130 into the Johnson tape drive 180. Therefore, the Johnson tape cartridge can be used with the Johnson tape drive 180. SDLT magnetic tape cartridge 230 is shown in Figure 9 engaging the door actuator assembly 248 of Figure 7. As the SDLT magnetic tape cartridge 230 slides along the SDLT tape drive receiver 250, the rib 210 passes into the slot 212 between the ramp 270 and the door actuator surface 274 to enable complete insertion of the SDLT magnetic tape cartridge 230 into the SDLT tape drive 280. The sensor 260, located in slot 212, senses the presence of rib 210 in slot 212 thereby providing a positive indication that a SDLT magnetic tape cartridge 210 is loaded in the SDLT tape drive 280. Therefore, the SDLT tape cartridge can be used with the SDLT tape drive 280 and the SDLT tape drive 280 receives a positive indication of the type of magnetic tape cartridge loaded therein. It is also obvious that the slot 212 is too small to enable the tab 110 of the Johnson magnetic tape cartridge 130 to pass through, thereby preventing the Johnson magnetic tape cartridge 130 from being used with the SDLT tape drive 280. However, this restricts the users of the SDLT tape drive 280 to the use of the SDLT magnetic tape cartridges 230 or the old generation magnetic tape cartridges 30. Figure 11 illustrates a perspective view of the present coded magnetic tape cartridge 430 and Figure 12 illustrates a schematic illustration of the door actuator assembly 248 of Figure 7, used with the present coded magnetic tape cartridge 430. Housing 232 includes an access door 234 that rotates about an axis 236 in the direction 238 when the present coded magnetic tape cartridge 430 is inserted into the SDLT tape drive receiver 250. The access door 434 includes a door latch 440 having a cut out 442. Side surface 444 of the present coded magnetic tape cartridge 430 includes a recess 446 that cooperatively engages with the SDLT access door actuator assembly 248 in the SDLT tape drive receiver 250. The present coded magnetic tape cartridge 430 has substantially the same form factor as the old generation, Johnson and SDLT magnetic tape cartridges 30, 130, 230, respectively except that the recess 446 includes a coding fin 410. The coding fin 410 may be integrally formed with the recess 446 or attached thereto with an adhesive. The SDLT tape drive receiver 250 includes an access door actuator assembly 248 having a ramp 270 and a door actuator surface 274. A slot 212 is formed between ramp 270 and the door actuator surface 274 to enable a rib 210, such as that formed on the SDLT magnetic tape cartridge 230 to pass through this slot 212. The sensor 260, located in slot 212, senses the presence of rib 210 in slot 212 thereby providing a positive indication that a SDLT magnetic tape cartridge 210 is loaded in the SDLT tape drive 280. Therefore, the SDLT tape cartridge can be used with the SDLT tape drive 280 and the SDLT tape drive 280 receives a positive indication of the type of magnetic tape cartridge loaded therein. It is also obvious that the slot 212 is too small to enable the tab 110 of the Johnson magnetic tape cartridge 130 to pass through, thereby preventing the Johnson magnetic tape cartridge 130 from being used with the SDLT tape drive 280. However the coding fin 440 of the coded magnetic tape cartridge 430 is of dimensions to pass through slot 212, yet of length smaller than rib 210, to thereby fail to activate sensor 260. Summary

The coded magnetic tape cartridge functions to control the compatibility of the magnetic tape cartridge with a plurality of existing tape drives, some of which are compatible in a transparent manner and others which are compatible in a way that mimic other magnetic tape cartridges.

Claims

What is Claimed:

1. A coded single reel magnetic tape cartridge that encloses a reel of magnetic tape, the reel consisting of a cylindrical-shaped hub and two flanges, one mounted respectively on the top and the bottom of the hub, the coded single reel magnetic tape cartridge being mountable in selected ones of a plurality of tape drives, where said plurality of tape drives includes: a first tape drive that includes a first receiver that accepts only a first type of single reel magnetic tape cartridge that has a side face that is devoid of features that extend outwardly from the surface of the side face in the upper half thereof, a second tape drive that includes a second receiver that accepts both said first type of single reel magnetic tape cartridge and a second type of single reel magnetic tape cartridge that has a lockout tab that comprises a feature that extends outwardly from the surface of the side face in the upper half thereof and perpendicular in direction to a direction of insertion of said magnetic tape cartridge into said first receiver, said feature preventing said second type of single reel magnetic tape cartridge from being inserted into said first receiver, a third tape drive that includes a third receiver that accepts only said first type of single reel magnetic tape cartridge and a third type of single reel magnetic tape cartridge that has a lockout rib feature that extends outwardly from the surface of the side in the upper half thereof and extends along a side of a single reel magnetic tape cartridge at a predetermined distance above a bottom of said single reel magnetic tape cartridge, said lockout rib feature preventing said third type of single reel magnetic tape cartridge from being inserted into said first receiver, such that a sensor located in the third tape drive detects the presence of said lockout rib feature only when said third type of single reel magnetic tape cartridge is inserted into said third tape drive, the present coded single reel magnetic tape cartridge being capable of loading in said second and said third type of tape drives, comprising: a reel consisting of a cylindrical-shaped hub and two flanges, one mounted respectively on the top and the bottom of the hub; a housing for enclosing said reel and comprising: a top and a bottom, coplanar with said two flanges and located above and below a respective one of said two flanges; a front including an access door to enable a tape drive to access said magnetic tape wound on said reel; a side face having mounted thereon a coding fin for enabling said second and said third types of tape drives to accept said coded single reel magnetic tape cartridge, said coding fin comprising a feature aligned to be parallel to the insertion direction, positioned to fit in the gap of the second tape drive and the slot of the third tape drive, but of length to fail to activate the sensor of the third tape drive.

2. The coded single reel magnetic tape cartridge of claim 1 wherein said coding fin is molded as part of said side face.

3. The coded single reel magnetic tape cartridge of claim 1 wherein said coding fin defines a type of magnetic tape housed therein.

4. A coded single reel magnetic tape cartridge that encloses a reel of magnetic tape, the reel consisting of a cylindrical-shaped hub and two flanges, one mounted respectively on the top and the bottom of the hub, the coded single reel magnetic tape cartridge being mountable in selected ones of a plurality of tape drives, where said coded single reel magnetic tape cartridge has the same form factor as each of a plurality of single reel magnetic tape cartridges, each of the housings of the plurality of single reel magnetic tape cartridges each including an access door that extends across a portion of a front face of said housing, and a recess formed in a side face of said housing, wherein a door latch is mounted on a pivot axis positioned adjacent to the recess, the housing of said coded single reel magnetic tape cartridge comprising: a coding fin projecting distally from said recess, said coding fin being positioned to contact a door actuator assembly in a first tape drive to prevent insertion of said coded single reel magnetic tape cartridge into a first tape drive in an insertion direction, the coding fin being formed to be parallel to said insertion direction and of dimensions smaller than a gap in a second type of tape drive to enable insertion of said coded single reel magnetic tape cartridge into said second type of tape drive in an insertion direction and of dimensions to pass through a slot formed in a third type of tape drive to enable insertion of said coded single reel magnetic tape cartridge into said third type of tape drive in an insertion direction.

5. The coded single reel magnetic tape cartridge of claim 4 wherein said coding fin is of dimensions to fail to activate a sensor located in said slot formed in said third of said plurality of single reel magnetic tape cartridges.

6. The coded single reel magnetic tape cartridge of claim 4 wherein said coding fin is molded as part of said side face.

7. The coded single reel magnetic tape cartridge of claim 4 wherein said coding fin defines a type of magnetic tape housed therein.

8. A coded single reel magnetic tape cartridge that encloses a reel of magnetic tape, the coded single reel magnetic tape cartridge being mountable in selected ones of a plurality of tape drives, where said plurality of tape drives includes: a first tape drive that includes a first receiver that accepts only a first type of single reel magnetic tape cartridge that has a side face that is devoid of features that extend outwardly from the surface of the side face in the upper half thereof, a second tape drive that includes a second receiver that accepts both said first type of single reel magnetic tape cartridge and a second type of single reel magnetic tape cartridge that has a lockout tab that comprises a feature that extends outwardly from the surface of the side face in the upper half thereof and perpendicular in direction to a direction of insertion of said magnetic tape cartridge into said first receiver and of dimensions smaller than a gap in a second receiver in said second of said type of tape drives to enable insertion of said coded single reel magnetic tape cartridge into said second tape drive in an insertion direction said feature preventing said second type of single reel magnetic tape cartridge from being inserted into said first receiver, a third tape drive that includes a third receiver that accepts only said first type of single reel magnetic tape cartridge and a third type of single reel magnetic tape cartridge that has a lockout rib feature that extends outwardly from the surface of the side in the upper half thereof and extends along a side of a single reel magnetic tape cartridge at a predetermined distance above a bottom of said single reel magnetic tape cartridge, said lockout rib feature preventing said third type of single reel magnetic tape cartridge from being inserted into said first receiver, and of dimensions to pass through a slot formed in a third type of tape drive to enable insertion of said coded single reel magnetic tape cartridge into said third type of tape drive in an insertion direction such that a sensor located in the third tape drive detects the presence of said lockout rib feature only when said third type of single reel magnetic tape cartridge is inserted into said third tape drive, the present coded single reel magnetic tape cartridge being capable of loading in said second and said third type of tape drives, comprising a housing for enclosing said reel comprising: a front including an access door to enable a tape drive to access said magnetic tape wound on said reel; a side face having mounted thereon a coding fin for enabling said second and said third types of tape drives to accept said coded single reel magnetic tape cartridge, said coding fin comprising a feature aligned to be parallel to the insertion direction, positioned to fit in the gap of the second tape drive and the slot of the third tape drive.

9. The coded single reel magnetic tape cartridge of claim 8 wherein said coding fin is molded as part of said side face.

10. The coded single reel magnetic tape cartridge of claim 8 wherein said coding fin defines a type of magnetic tape housed therein.