Electrical computers and digital data processing systems: input/ – Intrasystem connection – System configuring
Reexamination Certificate
1999-03-10
2001-09-11
Auve, Glenn A. (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
System configuring
C710S008000
Reexamination Certificate
active
06289405
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of computer systems, and in particular, to compatibility and related issues, for example, between a computer slot and a candidate device intended to be plugged into that slot.
2. Background Information
Recently it has become common to configure computer systems sing motherboards and/or backplanes having a number of slot connectors (or simply “slots” herein) for receiving a variety of add-on adapter card devices. In many computer systems, input/output (I/O) interfacing and various special purpose circuitry is provided using these add-on adapter cards which conveniently and simply plug-in to standard bus connectors on the main processor motherboard or backplane.
The cards typically have edge connectors with a number of relatively closely spaced metal contacts, on one or both sides of the card edge, and the corresponding slots similarly have a like number of closely spaced metal contacts therein. When the card edge connector is inserted in the slot connector, the corresponding contacts make electrical connection. Through these contacts and their electrical connection, the card device and the board system, e.g., a personal computer, communicate data, address and control signals, for example. The card device also generally obtains electrical energy from the personal computer system through two or more of the contacts.
A variety of adapter/connector/bus types and standards are known, and one of these is the peripheral component interconnect (PCI) standard. The PCI bus is a synchronous, processor independent, 32- or 64-bit bus that functions similarly to a processor local bus. The PCI bus can be thought of as a buffered intermediate or so-called mezzanine bus, that is, an extension of the processor local bus. It is coupled to the personal computer processor local bus by so-called “bridge” circuitry, but maintains its own separate set of circuits. The original PCI bus specification provided for a clock speed of 33 MHz, which provided a data transfer rate of 80-120 Mbs (million bytes per second) in a 32-bit environment (32-bit data bus width), and up to a 264 Mbs transfer rate in a 64-bit environment. The PCI bus operates on 5 volts, 3.3 volts, or both.
Other standard types include ISA (Industry Standard Architecture—8/16 bits) and EISA (Expanded ISA—32 bits), SCSI (Small Computer System Interconnect), MCA (Micro Channel Architecture), VLB (VESA—Video Electronics Standard Association—Local Bus), AGP (Accelerated Graphics Port), and USB (Universal System Bus), to name just a few of
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the more prominent. The newer bus types generally have higher bus speeds. For comparison purposes, the bus speeds can be referenced by the quantity of data transferred per second. The original IBM PC (IBM is a registered trademark of International Business Machine Corporation) had a bus speed of about 1 megabyte per second, the IBM AT about 4 megabytes per second, a typical ISA bus about 8 megabytes to a maximum of 16 megabytes per second, the EISA bus has 32 megabytes per second, the MCA bus 20-40 megabytes per second, the VESA VL-1 has 20-132 megabytes per second, the VESA VL-2 up to 264 megabytes per second, the 33 MHz PCI version 1.0 (32-bit) has 80-120 megabytes per second and the PCI version 2.0 (64-bit) up to 264 megabytes per second, as noted earlier.
Bus speeds are alternatively quantified by their clock frequency, e.g., in mega-Hertz (MHz). The trend is for bus speeds to increase. PCI bus speeds, for example, are now available at an operating speed of 66 MHz. Even higher bus speeds, e.g., 133 MHz, and bit widths, e.g., 128 bits, are inevitable. Motherboards with 100 MHz processor bus speeds are currently available in high-end personal computers (PC's), such as those using 450 MHz Pentium II processors. As processor and motherboard speeds increase, increased performance demands will be put on peripheral devices and their buses.
However, not withstanding standardization efforts, due in large part to technological advances, there are currently a variety of systems in use having different specifications, such as bus type and bus speed. An office network installation may have brand new PC's operating with 100 MHz processor bus speeds along side systems only a year or two old operating with 33 MHz or 66 MHz processor bus speeds. Similar differences in peripheral devices and their busses naturally also exist.
There may be older, so-called legacy devices, which use older interface technology, but which still have a considerable amount of useful life remaining. These legacy devices may represent a considerable capital and labor investment. For this reason, systems are sometimes designed to incorporate two or more peripheral bus standards on a single motherboard, e.g., PCI and EISA. It would not be unusual to encounter a system having a primarily PCI-based motherboard with an embedded PCI based video driver, PCI slots with network interface and/or modem cards, a parallel/serial interface card for mouse and printer, an on-board keyboard interface, an embedded USB bus interface, an embedded IDE bus for connecting to IDE based hard drives, an embedded floppy drive bus, one or more EISA slots with a legacy sound card, and having an SCSI interface card plugged-in for interfacing with an SCSI based scanner, for example.
Of course, there may be other reasons why slower bus speed systems and devices are still being configured, such as tradeoffs between cost and speed, for example.
Besides bus type and bus speed mentioned above, variations in the operating voltage levels provided, e.g., 3.3 volts versus 5 volts and/or 12 volts, also raise compatibility issues. Systems may be further differentiated by their bus/slot bit-width, e.g., 8-bit, 16-bit, 32-bit or 64-bit. For example, PCI busses include both 32-bit and 64-bit versions. Also, on some PCI motherboards, some of the PCI bus slots may be designated for bus master devices and some for bus slave devices.
There can also be differences in the available width, length or height clearance for card-slot electrical devices among the various available peripheral connectors and computer systems, depending on board layout, etc.
For example, the PCI standard supports both a long card form factor and a short card form factor. However, a particular system configuration may only permit a short card in a particular slot because of a lack of clearance with other installed system devices. That is, the may not be enough room for a long card in a particular slot. There may also be height clearances to consider for card devices that exceed the standard card device height. Cooling requirements may also be a factor in determining where a particular card device is or can be located in a particular system, as could electromagnetic field or other electrical interference issues, e.g., RFI (radio frequency interference). The preceding parameters are examples of what is referred to herein as “parametrics.” Information about these parameters is referred to herein as “parametric data.” (A parameter could be represented simply as a bit whose state indicates the parameter's value, such as in the long/short card form factor parameter mentioned above.)
It is further noted that some systems may have chassis slots for power supplies or cooling systems, for example, in addition to the backplane/motherboard slot connectors, whose parameters may affect system compatibility. Some power or cooling subsystems may be packaged in drawers which are designed to be inserted into and removed from a chassis slot as a unit, for example.
One the one hand, all the variety described above provides user choice and flexibility. On the other hand, when the various technologies need to be integrated, significant compatibility issues may frequently be presented.
It should be apparent that, even in systems which use “standard” PCI slots, for example, there are any number of situations where “compatibility” questions between a computer slot and a candidate device can arise. Examples of some of the more common situati
Movall Paul Edward
Osten Thomas James
Auve Glenn A.
International Business Machines - Corporation
Lynt Christopher H.
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