Backward compatibility for plug and play systems
First Claim
1. A backward compatible plug and play device for adaptive use with a computer of either a PNP or a legacy non-PNP type having system data and address busses, said device being coupled to said computer system data and address busses, said device comprising:
- first storage means, coupled to said computer system data bus, for storing an I/O address for the device, wherein said first storage means outputs a default I/O address upon power-up;
a DMA channel register, coupled to said computer system data bus, for storing a DMA channel value for the device, wherein said DMA channel register outputs a default DMA channel value upon power-up;
an interrupt level register, coupled to said computer system data bus, for storing an interrupt level value for the device, wherein said interrupt level register outputs a default interrupt level value upon power-up; and
control logic, coupled to said first storage means, said computer system address bus and said computer system data bus, wherein said control logic;
upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign I/O addresses to a device, disables said device and allowes a computer system to write to said first storage means an I/O address;
upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign DMA channel value to a device, allows a computer system to write to said DMA channel register a DMA channel value; and
upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign interrupt level value to a device, allows a computer system to write to said interrupt level register an interrupt level value.
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Accused Products
Abstract
A device for use in a computer system, particularly a personal computer (PC) which provides compatibility for a proposed ISA plug and play (PNP) standard. The device of the present invention is also backward compatible with non-PNP (legacy) PCs. Upon power-up, a device may initialize using default traditional or specification (ISA) values for I/O address, IRQ and DMA channels. If PNP activity by the host PC is detected by the device, the device is disabled, and awaits activation and I/O address, IRQ and DMA channel assignments from a host PC. If no PNP activity by a host PC is detected, the device continues to operate using default traditional or specification (ISA) I/O address, IRQ and DMA channels. The device of the present invention may be installed in PNP or legacy type PCs without reconfiguring hardware (e.g., DIP switches, jumpers or the like) in the device or installing new firmware, operating system, or applications software in a host PC.
56 Citations
13 Claims
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1. A backward compatible plug and play device for adaptive use with a computer of either a PNP or a legacy non-PNP type having system data and address busses, said device being coupled to said computer system data and address busses, said device comprising:
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first storage means, coupled to said computer system data bus, for storing an I/O address for the device, wherein said first storage means outputs a default I/O address upon power-up; a DMA channel register, coupled to said computer system data bus, for storing a DMA channel value for the device, wherein said DMA channel register outputs a default DMA channel value upon power-up; an interrupt level register, coupled to said computer system data bus, for storing an interrupt level value for the device, wherein said interrupt level register outputs a default interrupt level value upon power-up; and control logic, coupled to said first storage means, said computer system address bus and said computer system data bus, wherein said control logic; upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign I/O addresses to a device, disables said device and allowes a computer system to write to said first storage means an I/O address; upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign DMA channel value to a device, allows a computer system to write to said DMA channel register a DMA channel value; and upon detecting activity on said computer system data bus characteristic of a computer system attempting to assign interrupt level value to a device, allows a computer system to write to said interrupt level register an interrupt level value. - View Dependent Claims (2, 3, 4, 5)
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6. A method for adaptively operating a backward compatible plug and play device with a computer of either a PNP or a legacy non-pNP type having system data and address busses, said device being coupled to said computer system data and address busses, said method comprising the steps of:
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storing, in a first storage means coupled to said computer system data bus, a default I/O address upon power-up; storing, in a DMA channel register coupled to said computer system data bus, a default DMA channel value upon power-up; storing, in an interrupt level register coupled to said computer system data bus, a default interrupt level value upon power-up; detecting activity on said computer system data bus characteristic of a computer system attempting to assign I/O addresses to devices; and allowing a computer system to write to said first storage means an I/O address upon detection of said activity. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification