Electrical connectors – With selectable circuit – e.g. – plug board
Reexamination Certificate
2001-02-08
2003-06-03
Bradley, P. Austin (Department: 2833)
Electrical connectors
With selectable circuit, e.g., plug board
C710S104000
Reexamination Certificate
active
06572384
ABSTRACT:
COPYRIGHT NOTICE AND AUTHORIZATION
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
The present invention relates to a motherboard and removable circuit card architecture and interface for use in computer systems.
BACKGROUND OF THE INVENTION
Typically, a computer includes of a motherboard containing components, such as a main processor or central processing unit (“CPU”), memory, disk storage and other devices. These components normally transfer data to the CPU through a local data and address bus.
To provide additional functionality to one's computer, a user may plug a peripheral expansion card into one of a number of connectors or slots into the computer's motherboard. Additionally, one or more peripheral expansion cards may transfer data to the CPU through an external input/output (“I/O”) bus via a connector on the motherboard. As a result, the CPU's external bus permits the computer to be expanded using a modular approach. For example, peripheral expansions of a computer may include adding a sound subsystem, a video subsystem, a communications subsystem, a compact disc (“CD”) device, a storage device or hard drive, an instrumentation interface, or other special function expansions to the PC computer.
Typically, these peripheral expansion cards have pins on the edge of the card interfacing to a connector on the motherboard in order to provide electrical connections between the electronic circuits on the peripheral expansion card and the components, such as the CPU, on the motherboard. Then, the components can access these electrical circuits on the peripheral card via the CPU's external I/O bus. Further, each electrical connection on the external I/O bus typically provides a specific function. For example, one set of connections may provide the voltages required to power the peripheral expansion card (for example, +5, +12, and ground). Another group of connections might enable the data bus to transmit data between the CPU and the electronic circuits. A third group of contacts can provide the address bus in order to permit the device to be addressed through a set of I/O addresses. Finally, there may be contacts for control or other signals such as interrupts requests (“IRQ's”), direct memory access (“DMA”) channels, and clock signals.
One of the earliest PC buses is named the “8-bit bus” (also known as the XT bus) because early PCs often had 8 bit processors like the Intel 8085 and 8088. This 8-bit bus has eight interrupts (of which six could be used by peripheral expansion cards), four DMA channels, a 62 pin connector and a CPU with a clock speed of 4.77 MHz. However, the installation of a peripheral expansion card requires manual configuration to utilize available computer resources such as DMA channels, IRQs, and I/O addresses. Additionally, each peripheral expansion card is separately configured in order to avoid a conflict with another device that utilizes the bus. Each card is configured for a particular computer by using jumpers and dual in-line package switches (“DIP”) to operate with the computer according to instructions defined by the manufacturer.
The introduction of the IBM AT computer resulted in the development of a bus known as the Industry Standard Architecture (“ISA”) bus. However, the ISA bus is a 16-bit bus because the IBM AT computer has a 16-bit processor such as the Intel 8086. The ISA bus is based on the “8-bit bus” connector with the addition of a small bus connector adding several signal lines to widen the data bus to 16-bits. In addition to the extra resources, the ISA bus is backward compatible with the older 8-bit bus. The ISA bus also adds eight more interrupts, additional data and address lines, and four additional DMA channels. Further yet, improvements over the XT bus include an increased clock speed of 8 MHz for the ISA bus with “Turbo” models running near 10 MHz. Additionally, the ISA bus is capable of “bus mastering” allowing a device on a peripheral card to take control of the bus to read or write directly from another device while the CPU is momentarily idled. As a result, bus mastering can greatly improve the data transfer performance of a computer.
Both the XT and AT bus typically operate at the same clock speed as the CPU, namely 4.77 MHz and 8 MHz, respectively. However, when newer CPUs outpaced the 8 MHz bus, such as with the early 12 MHz Intel '286 CPUs, the maximum speed of the bus limited the CPU clock speed. For instance, if the CPU clock is tied to the ISA bus having a clock speed of 8 MHz, then a faster CPU such as the 12 MHz Intel 286 CPU would be forced to operate at an 8 MHz CPU clock speed despite the '286 CPU's increased operating speed. Rather than force the '286 CPU to operate at a slower clock speed, one solution was to separate the '286 CPU clock from the I/O bus clock (i.e. 8 MHz), so that the '286 CPU could run at it's maximum speed (i.e. 12 MHz). Consequently, de-coupling the I/O bus from the 3286 CPU bus allows the I/O bus to operate at 8 MHz while the CPU clock may operate at 12 MHz.
As in the 8-bit bus however, the ISA bus may be configured using the same manual procedures for configuring the 8-bit expansion cards. As a result, resources such as interrupt memory addresses, DMA channels, and I/O ports are manually configured using jumpers and DIP switches. Alternatively, one special method of configuring an ISA bus expansion card is based on an ISA “Plug-and-Play” system. According to the ISA “Plug-and-Play” system, ISA cards may also be configured using an Electronically Erasable Programmable Read Only Memory (“EEPROM”) chip on the card. Essentially, the jumper positions of the manual re-configuration method are programmed into the EEPROM and the settings could be made using a special software configuration program.
To operate properly, the ISA “Plug-and-Play” (“PnP”) system is comprised of a standard ISA bus and a special set of Basic Input/Output System (“BIOS”) extensions. In theory, these BIOS extensions examine the installed “Plug-and-Play” compatible cards at start up and set expansion cards to available resource settings. Despite intentions to make configuring an ISA card easy, the ISA “Plug-and-Play” method failed because the ISA “Plug-and-Play” enumeration algorithm was not widely accepted. As a result, conflicts between the CPU and the expansion card were frequent because the configuration system would not know about the existence of other non-PnP cards. Consequently, “Plug-and-Play” soon earned the nickname in the computer service industry as “Plug and Pray”.
IBM later developed a bus using a higher density connector known as Micro-Channel Architecture (“MCA”). The MCA bus was available in either 16-bit or 32-bit versions and featured multiple bus mastering. Although the MCA bus clock speed was set at 10 MHz, the MCA allowed change configurations under software control rather than with jumpers and DIP switches. Consequently, a user can configure an MCA peripheral card to use available resources such as IRQ, DMA channel, memory address, and I/O ports using a reference disk and an option diskette after installing the physical device in the computer. The reference disk is a special bootable disk containing a program that sends commands to bus devices to configure their parameters. This reference disk is included with the computer and is unique to the particular MCA bus computer. Each MCA peripheral card also comes with an option disk containing the device specific configuration files for the device being installed. Nevertheless, computer systems designers do not extensively use the MCA bus because it is not backward compatible with the ISA bus.
The Extended Industry Standard Architecture (“EISA”) open
3Com Corporation
Bradley P. Austin
León Edwin A.
McDonnell & Boehnen Hulbert & Berghoff
LandOfFree
Method and apparatus for interconnecting circuit cards does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for interconnecting circuit cards, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for interconnecting circuit cards will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3089079