SCSI adapter for a computer system having an internal SCSI bus

A SCSI adapter for extending an internal SCSI bus of a computer system having a housing and internal memory storage devices is disclosed herein. The SCSI adapter enables connection of external memory storage devices to the internal SCSI bus. The SCSI adapter includes an adapter plate and a SCSI bus extension. The adapter plate attaches within the housing to the internal SCSI bus and to the SCSI bus extension. The SCSI bus extension extends from the adapter plate and attaches to the housing to enable connection of external memory storage devices with the internal SCSI bus.

FIELD OF THE INVENTION 
This invention relates generally to computer systems. More particularly, 
this invention relates to computer systems having an internal SCSI bus. 
BACKGROUND OF THE INVENTION 
The demand for increased memory storage capacity in computer systems is 
driven by developments in computing such as those relating to multimedia, 
database and communications technology. Desktop computers are now able to 
manage databases, generate and display video images and digitally recorded 
sound. Such applications require much more memory storage capacity than 
many textual documents require. 
With the increased demand for memory storage, there is a need to adapt 
presently existing computer systems with more powerful memory storage 
systems. One way to provide more powerful memory storage systems to 
existing computer systems is to attach additional memory storage devices 
to an existing system. Many systems, however, are limited in the number of 
memory storage devices which can be attached. What is desired is a way to 
expand the number of memory storage devices which can be attached to a 
computer system. 
Small Computer Systems Interface (SCSI) is a known architecture having an 
interface with at least one SCSI bus which links memory storage devices to 
a computer system. A single SCSI bus may attach to numerous (e.g. 8) 
memory storage devices. 
There is at least one computer system on the market which includes an 
internal and an external SCSI bus. An example of such a computer system is 
marketed under the trade name "Indigo 2" by Silicon Graphics, Inc. The 
computer includes a housing which encases a motherboard having a 
processor. The housing has adequate space for three internal memory 
storage devices. The internal SCSI bus interconnects the internal memory 
storage devices to the motherboard. The external SCSI bus extends from the 
motherboard to an external connector which is connectable with external 
memory storage devices which are external to the housing. An example of a 
computer system having an internal and an external SCSI bus is shown in 
FIG. 1. 
Although, there is sufficient space in the computer system housing to house 
up to three internal memory storage devices, the internal SCSI bus has 
sufficient throughput capacity to enable attachment with more than three 
memory storage devices. What is desired is a way of attaching additional 
memory storage devices to the internal SCSI bus to increase the memory 
storage capacity of the computer system. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a way of interconnecting 
external memory storage devices to an internal SCSI bus. 
In accordance with the above objects recited above and those that will 
become apparent below, an adapter plate for interconnecting an internal 
SCSI bus of a computer system with a SCSI bus extension to enable 
electronic attachment of external memory storage devices to the internal 
SCSI bus, comprises: 
a first connector attachable with the internal SCSI bus; 
a second connector attachable with the SCSI bus extension, 
whereby, when the first connector attaches to the internal SCSI bus and the 
second connector attaches with the SCSI bus extension, the adapter plate 
facilitates attachment of external memory storage devices to the internal 
SCSI bus. 
In a preferred embodiment, the adapter plate attaches with the SCSI bus 
extension. The SCSI bus extension has a connector attachable with memory 
storage devices. 
In another preferred embodiment, the adapter plate includes a third 
connector. The adapter plate attaches to a memory storage device carrier 
to facilitate interconnection of the third connector with an internal 
memory storage device. 
In another preferred embodiment, the adapter plate has a width of 
approximately six inches and a height of approximately two inches. The 
adapter plate includes a pair of keyhole mounts, the keyhole mounts being 
approximately 55/8" apart to enable attachment of the adapter plate to a 
memory storage device carrier having pin mounts which are approximately 
55/8" apart. 
In another preferred embodiment, the first connector is an eighty pin type 
connector and the second connector is a fifty pin type connector. The 
adapter plate includes a circuit assembly which attaches between the first 
connector and the second connector. The circuit assembly terminates 
selected pins of the of the first connector to enable electronic 
compatibility between the first connector and the second connector. 
It is an advantage of the present invention to provide an apparatus which 
interconnects external memory storage devices with an internal SCSI bus of 
a computer system.

DETAILED DESCRIPTION OF THE INVENTION 
With particular reference to FIG. 1 there is shown a computer system 
generally designated by the reference numeral 10. The computer system 10 
includes a housing 12, a motherboard 14, memory storage device carriers 16 
and 17, an internal SCSI bus 18, an external SCSI bus 20 and memory 
storage devices 22 and 24. 
The memory storage device carrier 16 removeably holds the memory storage 
device 24. The memory storage device carrier 17 removeably holds the 
memory storage devices 22. An example of a memory storage device carrier 
for removeably holding memory storage devices are disclosed in commonly 
assigned U.S. Pat. No. 5,518,412, issued May 21, 1996, the disclosure of 
which is incorporated by reference. 
Each of the memory storage devices 22 include a 31/2 inch hard disk drive. 
The memory storage device 24 includes a 51/4 inch hard disk drive. The 
memory storage devices 22 and 24 electronically connect with the internal 
SCSI bus 18 via the memory storage device carriers 16 and 17, 
respectively. It can be appreciated that each memory storage device need 
not include a hard disk drive and may, for example include a floppy disk 
drive, a tape drive, an optical disk drive, or some other type of memory 
storage device. 
The housing 12 encloses the motherboard 14, a motherboard cooling fan 15, 
the memory storage devices 22 and 24, and the internal SCSI bus 18. The 
internal SCSI bus 18 has eighty pin type SCSI connectors 19 which attach 
to the motherboard 14 and to the memory storage devices 24. The internal 
SCSI bus 18 electronically connects with the memory storage devices 22 via 
the memory storage device carrier 17. 
The internal SCSI bus 18 has a terminal end 32 which terminally connects 
with the memory storage device carrier 16 which holds the 51/4 inch memory 
storage device 24. The term "internal SCSI bus" is defined as a SCSI bus 
which normally interconnects a motherboard with internal memory storage 
devices. The term "internal memory storage device" is defined as a memory 
storage device which is electronically attachable with a computer system 
and housed within the computer system housing. 
The external SCSI bus 20 attaches to the motherboard 14 and includes an 
external connector 26. The external connector 26 attaches with the housing 
12 and enables the connection of external memory storage devices (not 
shown). The term "external SCSI bus" is broadly defined as a SCSI bus 
attached to the motherboard and having a connector which normally enables 
connection of external memory storage devices with the motherboard via 
SCSI architecture. The term "external memory storage device" is defined as 
a memory storage device which is electronically attachable with a computer 
system, but not normally enclosed by the computer system housing 12. 
With particular reference to FIG. 2, there is shown the SCSI adapter of the 
present invention generally designated by the reference numeral 36. The 
SCSI adapter 36 includes an adapter plate 38, a SCSI bus extension 40 and 
an external SCSI connector 42. 
The adapter plate 38 attaches to the memory storage device carrier 16, to 
the internal SCSI bus 18 and to the SCSI bus extension 40 to enable 
additional memory storage devices to attach to the internal SCSI bus 18. 
The SCSI bus extension 40 has one end attached to the adapter plate 38 and 
another end which attaches to the external connector 42. The external 
connector 42 is connectable with external memory storage devices. 
Accordingly, the SCSI adapter 36 enables connection of external memory 
storage devices with the internal SCSI bus 18. 
The SCSI adapter 36 includes a fixed port cover 44. The external connector 
42 inserts within the fixed port cover 44. The fixed port cover 44 
includes a flat plate having threaded holes and bolts which attach the 
external connector 42 and the SCSI bus extension to the housing 12. 
With particular reference to FIG. 3, there is shown the SCSI adapter 36 
having a removeably expansion slot cover 46. The housing 12 includes 
expansion slot openings 48. One end of the SCSI bus extension 40 attaches 
to the adapter plate 38. The other end of the SCSI bus extension 40 
inserts into the expansion slot cover 46. The expansion slot cover 46 
attaches to the housing 12 over one expansion slot opening 48. 
With particular reference to FIG. 4, there is shown the SCSI adapter 36. 
The adapter plate 38 has a front side 52 and a rear side 54. Connectors 50 
and 56 attach to the front side 52. A connector 51 attaches to the rear 
side 54. The connectors 50 and 51 are eighty pin type SCSI connectors. The 
connector 56 is a fifty pin type SCSI connector. 
The connector 51 is attachable to a memory storage device having an eighty 
pin type connector. The connector 50 is attachable with the internal SCSI 
bus 18 (FIG. 2). The connector 56 is attachable with the SCSI extension 
40. 
The adapter plate 38 includes numerous vents 58, keyhole mounts 60, 
fastener holes 62, and a circuit assembly 64. The circuit assembly 64 is 
formed integral with the adapter plate 38 to electronically interconnect 
the connectors 50, 51 and 56. The circuit assembly 64 serially connects 
the connector 50, the connector 51 and the connector 56 to establish 
electronic communication between the connectors. 
Each connector 50, 51 and 56 includes contact pins 65 which extend from 
each connector 50, 51 and 56 to the circuit assembly to electronically 
connect with the circuit assembly 64. The circuit assembly 64 
electronically disables (terminates) current from selected contact pins 65 
of the connector 51 to form a compatible electronic connection between the 
connector 56 and the internal SCSI bus 18 (FIG. 2) when the SCSI bus 18 
attaches to the connector 50. Accordingly, the adapter plate 54 enables a 
fifty pin type connection with the internal SCSI bus 18 which has eighty 
pin type connectors. 
The SCSI bus extension 40 has two ends. A connector 66 attaches to one end, 
the external connector 42 attaches to the other end of the SCSI bus 
extension 40. In one embodiment each connector 66 and 42 are fifty pin 
type connectors. 
The expansion slot cover 46 is generally "L" shaped having one end with a 
fastener slot 70 and a flat side having an opening 72. The external 
connector 42 inserts through the opening 72 and attaches to the expansion 
slot cover to hold the external connector 42 and to enable attachment of 
external memory storage devices to the internal SCSI bus 18 (FIG. 2) via 
the external connector 42. 
With particular reference to FIG. 5, there is shown the adapter plate 38 
and the memory storage device carrier 16. The carrier 16 includes a pair 
of pins 74. Each pin 74 has a flat head 76. The adapter plate 38 includes 
the keyhole mounts 60. The keyhole mounts 60 slidably attach over the pins 
74 when the adapter plate 38 attaches to the memory storage device carrier 
16. The adapter plate 38 includes fasteners 78 which fasten the adapter 
plate 38 to the memory storage device carrier 16. 
The memory storage device carrier 16 has a face plate 82 with an opening 80 
for receiving a SCSI connection. The eighty pin connector 51 mounts on the 
rear side 54 of the adapter plate 38 and extends through the opening 80 to 
enable interconnection of the connector 51 with the memory storage device 
24 (FIG. 2). 
The adapter plate 38 has a width "w" of approximately six inches and a 
height "h" of approximately two inches. "Approximately" as used in this 
document denotes a value +.backslash.-10% of the value. 
The keyhole mounts 60 are separated a distance d.sub.1 when measured on 
center. The adapter plate 38 has four sides including a top side 86. The 
keyhole mounts 60 are positioned a distance d.sub.2 from the top side 86. 
Each keyhole mount 60 has a center 84. In one embodiment, d.sub.2 is 
approximately 3/4 of an inch and d.sub.1 is approximately 55/8 inches when 
measured from the center 84 of each keyhole opening 20. 
While the foregoing detailed description has described several embodiments 
of the platter in accordance with this invention, it is to be understood 
that the above description merely illustrative and does not limit the 
scope of the claimed invention. Particularly, the adapter plate may have 
many shapes and configurations which enable connection of the SCSI bus 
extension to an internal SCSI bus. Additionally the SCSI bus extension may 
be adapted to connect with memory storage devices without requiring 
attachment to the housing. Further, the present invention is useful for 
expanding memory storage capacity of any of a variety of computer systems. 
The invention is to be limited only by the claims as set forth below.