Method and apparatus for isolating circuit boards in a computer system

• US 5,692,189 A
• Filed: 07/05/1994
• Issued: 11/25/1997
• Est. Priority Date: 07/05/1994
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lipe, Ralph A.
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): PARK, ALICE
• Application Number:
  US08/270,670
• Time in Patent Office: 1,239 Days
• Field of Search: 395/700, 395/280-280.3, 395/285-285.3, 395/829, 395/401, 395/403, 395/830, 395/651-653, 364/280, 364/280.2, 364/280.3, 364/285, 364/285.3
• US Class Current: 713/1
• CPC Class Codes: G06F 12/0684 with feedback, e.g. presence or absence of unit detected by addressing, overflow detection
• CPC Class Codes: G06F 13/4068 Electrical coupling

Abstract

A method of individually isolating a circuit board that has been added to an expansion slot of a computer system. If a conflict exists between the circuit board and other resources of the computer system, the present invention isolates the memory resource requirements of the circuit board from the computer system. The memory resources requirements of the circuit board may be isolated from the computer system by disabling access to the memory of the computer system which is generally designated for circuit board use. Access to this memory may be disabled by disabling an address line of the expansion slot in which the circuit board has been added. In a computer system utilizing an industry standard bus system the present invention disables address A19 of the expansion slot. A latch is typically coupled to the address line corresponding to the memory range generally designated for circuit board use for selectively disabling the address line so that memory resources requirements of the circuit board is isolated from the computer system. The present invention also may isolate the input and output resource requirements of the circuit board from the computer system while the memory resources are isolated. The input and output resource requirements of the circuit board may be isolated by selecting a control line that prevents the circuit board from communicating with input and output lines of computer system.

Claims

1. An apparatus for resolving resource conflicts within a computer system and having computer system resources interfaced via a computer system bus, said resource conflicts associated with the installation of a circuit board to said computer system, comprising:

a central processing unit connected to said computer system bus;

a memory unit connected to said computer system bus;

a slot connected to said computer system bus and coupling said circuit board to said computer system bus;

a latch connected to the address line of said slot that is operative for addressing the portion of said memory corresponding to default memory assignments for said circuit board, the output of said latch being connected to said address line of said slot and the inputs lines of said latch being connected to said computer system bus and said input lines operative to receive input signals from said central processing unit;

said central processing unit operative to generate an activating input signal, via said computer system bus, to said latch upon detection of a resource conflict; and

said latch responsive to said activating input signal to provide an output signal to said address line to selectively disable access by said circuit board to said memory unit.

2. The apparatus of claim 1 wherein said latch is connected to address line A19 of said slot.

3. The apparatus of claim 2 further comprising a control line of said computer system bus connected to said slot for disabling communications via said input and output ports.

4. The apparatus of claim 3 wherein said control line is the address enable line.

5. A computer system characterized by resources including a central processing unit, a memory, input and output ports and expansion slots for receiving circuit boards, and an address bus, a data bus and a control bus connected to said resources, said circuit boards being initially configured to operate in a certain memory range, comprising:

means for beginning start-up procedures for said computer system, said start-up procedures beginning initialization of said circuit boards of said computer system; and

means for continuing said start-up procedures, while said circuit boards remain in said expansion slots, when said certain memory range is assigned for use by another resource of said computer system, thereby causing a memory conflict, and when said computer system would normally be interrupted due to said memory conflict.

6. A general purpose computer system characterized by resources including a central processing unit, a memory, input and output ports and expansion slots for receiving circuit boards and an address bus, a data bus and a control bus connected to said resources for preventing resource conflicts within a computer system when a circuit board is added to said system, comprising:

a central processing unit for determining when a resource conflict occurs and for providing an output signal indicative of a resource conflict; and

a latch, connected to a certain address line of said address bus of one of said expansion slots, for controlling access to a portion of said memory by said circuit board, said latch being responsive to said output signal for selectively disabling access to said portion of said memory via said certain address line.

7. The system of claim 6 wherein said address line is address line A19.

8. In a general purpose computer system characterized by resources including a central processing unit, a memory, expansion slots for receiving circuit boards, input and output ports and a computer system bus including an address bus, a data bus and a control bus connected to said resources, a computer-implemented method of preventing memory conflicts within said computer system when a certain one of said circuit boards is added to an expansion slot of said computer system, comprising the steps of:

beginning start-up procedures for said computer system;

determining whether a memory conflict exists within said computer system when said certain circuit board is added to said expansion slot;

in response to determining said memory conflict, activating an address enable (AEN) control line operative to control input and output operations of said certain circuit board with said computer system, thereby preventing said certain circuit board from communicating via said input and output ports of said computer system;

in response to determining a memory conflict, providing a control signal from said central processing unit to a latch, said latch being connected to said central processing unit and to an address line A19 of the expansion slot containing said certain circuit board, said address line A19 operative for addressing the portion of said memory corresponding to default memory assignments for said certain circuit board; and

in response to said control signal, said latch disabling said address line A19 while said certain circuit board remains in said expansion slot.

9. A computer-readable medium on which is stored a program module for preventing conflicts within memory of a computer system when a certain circuit board is added to an expansion slot of said computer system, comprising instructions which, when executed by said computer system, perform the steps of:

determining whether a memory conflict exists within said computer system when said certain circuit board is added to said expansion slot;

in response to determining said memory conflict, activating an address enable (AEN) control line operative to control input and output operations of said certain circuit board with said computer system, thereby preventing said certain circuit board from communicating via said input and output ports of said computer system;

in response to determining a memory conflict, providing a control signal to a latch, said latch being connected to a central processing unit (CPU) and to an address line A19 of the expansion slot containing said certain circuit board, said address line A19 operative for addressing the portion of said memory corresponding to default memory assignments for said circuit board; and

in response to said control signal, said latch operative to disable said address line A19 while said certain circuit board remains in said expansion slot.