Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus expansion or extension
Reexamination Certificate
2000-06-30
2004-03-09
Vo, Tim (Department: 2189)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus expansion or extension
C710S300000, C710S301000, C710S304000, C307S140000, C307S147000
Reexamination Certificate
active
06704825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to connecting cards in computer systems. More particularly, the present invention relates to preventing power damage to cards and other peripherals.
2. Description of the Related Art
An interface bus is a path inside a computer system for transferring data between a processor and other computer peripherals. Developed by Intel Corporation and other industry leaders in 1993, the Peripheral Component Interconnect (PCI) local bus has become the standard interface bus for high-speed devices. A conventional PCI bus includes a 64-bit bus. More typically implemented as a 32-bit data path and operating at 33 megahertz (MHz), the PCI bus boasts a maximum data transfer rate of 132 megabytes/second.
The standard PCI bus has attained market dominance, not only because of its performance capabilities, but also because of the flexibility and expandability of the PCI system. Most PCI systems support several peripherals, which may be integrated directly onto the motherboard or be added on a PCI expansion card. These PCI cards, each of which may include peripherals having multimedia, graphics, video, disk drive, or network capabilities, allow a user to customize and re-customize a computer system at any time.
A PCI system also gives a user the flexibility of removing and replacing a damaged or obsolete PCI card without replacing the entire motherboard.
A PCI card may be installed almost effortlessly into a computer system by sliding the PCI card into a PCI slot, after the power to the PCI slot has been disabled. Once a PCI card is properly installed, a “plug and play” feature may then be used to complete integration of the peripheral into the computer system. A PCI card may also be easily uninstalled by first disabling power to the PCI slot and then removing the PCI card. In addition, advances in the server technology have made it possible to replace cards while the system is running by disabling power only to one particular PCI slot (Hot plug). This is important because many high-end servers, such as ones servicing a high volume web portal, cannot tolerate any down time because users are sending large numbers of requests to the server every second of the day.
It is critical that power to the PCI slot be turned off or disabled during installation or removal of a PCI card. If power to the PCI slot is not disabled, then a high transient Is voltage and a high voltage imbalance may occur when the contacts of the PCI card and PCI slot are pulled or pushed together. Unleashing such uncontrolled voltages would be uextremely undesirable, particularly for a high-end server. Electric currents generated by the voltages would likely cause damage not only to the PCI card, but also to other components on the motherboard. Voltage transients can also be induced to the signal bus and create data errors. Because PCI cards are installed and uninstalled by hand, a mechanism must be provided to ensure that power is disabled to a particular PCI slot before installation or uninstallation of a PCI card.
FIG. 1
is an illustration of a conventional hot swap system
10
known in the art that ensures power is disabled to a slot before removal of a card. Hot swap system
10
includes a chassis frame
12
having a slot
14
for receiving a card
16
(such as a PCI card for a hot swap PCI (HSPCI) system). A rocker
18
in a closed state secures card
16
to slot
14
by a rocker
18
(as shown). Rocker
18
includes a hinge
20
and a ridge
22
as well as a lock closed mechanism. Rocker
18
is rotably coupled to chassis frame
12
with hinge
20
. Hot swap system
10
also includes a printed circuit board (PCB)
24
coupled to chassis frame
12
. PCB
24
includes a mechanical switch
26
and may include indicator lights.
To install or uninstall card
16
from slot
14
, a user must unlatch the lock mechanism and rotate rocker
18
about hinge
20
to an open state as shown by an arrow
28
. The rotation of rocker
18
forces ridge
22
to depress mechanical switch
26
. When mechanical switch
26
is actuated, the logic in PCB
24
or the chipset, disables power to slot
14
. Therefore, hot swap system
10
releases card
16
and cuts the power to slot
14
at the same time. By ensuring that the power is disabled before card
16
is installed or uninstalled from slot
14
, hot swap system
10
prevents damage to card
16
and other computer components from transient and imbalanced voltages as described above.
One problem with hot swap system
10
is that mechanical switch
26
has a physical connection to rocker
18
and prone to being unreliable. For example, if a user flips rocker
18
to an open state too quickly, mechanical switch
26
may snap from the excessive friction and pressure applied by ridge
22
. Furthermore, mechanical switch
26
may become prone to breaking over time from being pressed too many times by ridge
22
. Mechanical switch
26
is susceptible to switch intermittence if the computer system experiences any vibrations or shock (e.g., from user loading). Mechanical switch
26
is also susceptible to oxidation over time, which could make mechanical switch
26
more difficult to press down.
While efforts have been taken to improve the quality of mechanical switch
26
, the failure rate of conventional hot swap system
10
is still unacceptable, particularly in high-end applications. If a card is removed from a slot while the power is still turned on, the damage to the computer system could be very costly. Furthermore, in a high-end system, such as a server powering an active commercial web site, any down time for the server is undesirable, especially if it is necessitated simply because of a mechanical switch failure. Therefore, it is desirable to have a method and apparatus that disables power prior to the installation or removal of a card with virtually no failures.
REFERENCES:
patent: 5530302 (1996-06-01), Hamre et al.
patent: 6355991 (2002-03-01), Goff et al.
Anderson Mark W.
Eckblad Michael Z.
Eylon Eryan
Flamm Ron
Gordon Glen P.
Steiner Paul E.
Vo Tim
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