System for selectively controlling slots in an IBM-AT/NEC 9801 dual-compatible computer

• US 5,109,517 A
• Filed: 10/09/1990
• Issued: 04/28/1992
• Est. Priority Date: 10/09/1990
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: AST Research, Inc. (Samsung Electronics Co. Ltd.)
• Inventors: Houda, Pavel, Lau, Yip-Shing
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Treat, William M.
• Application Number:
  US07/594,835
• Time in Patent Office: 567 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 710/104
• CPC Class Codes: G06F 13/4063 Device-to-bus coupling

Abstract

A system for selectively controlling individual expansion slots in an IBM-AT/NEC 9801 dual compatible computer provides automatic control for the individual ISA bus expansion slots in the computer. This facilitates the use of an Industry Standard Architecture (ISA) bus and ISA (AT) type add-on cards in the dual compatible computer. A user configures each slot as containing either a card which may interfere with operations of the computer in the non-IBM-AT compatible mode or a card which will not interfere with computer operations in the non-IBM-AT compatible mode. Thereafter, the computer automatically disables the cards in accordance with the mode of computer operation.

Claims

1. A dual mode computer which selectively functions in an IBM-AT compatible mode and a non-IBM-AT compatible mode, said dual mode computer including an Industry Standard Architecture (ISA) bus having a plurality of slots for receiving circuit boards therein, said ISA bus including a control bus comprising standard memory and I/O read and write signals and other control signals to control the operation of circuit boards in said slots of said ISA bus, said slots further adapted to receive master circuit boards, which can control said ISA bus, said computer including an additional mode indication signal which indicates whether the computer is operating in said IBM-AT compatible mode or said non-IBM-AT compatible mode, comprising:

at least one AT-only circuit board connected to said ISA bus which functions properly in response to signals on said ISA bus when the computer is operating in said IBM-AT compatible mode and which functions improperly and interferes with the operation of the computer if enabled when the computer is operating in said non-IBM-AT compatible mode;

a plurality of switches to configure each of said plurality of slots, each switch providing a respective slot configuration signal indicating whether said AT-only circuit board is connected in that slot; and

slot control logic responsive to said mode indication signal and to said slot configuration signal to automatically enable or disable a slot so that said AT-only circuit board is enabled only when the computer is operating in the IBM-At compatible mode, said slot control logic further responsive to a master signal to further select the direction of propagation of said control signals through said slot control logic so that said master circuit board, if installed, can assume control of said ISA bus.

2. The slot control logic of claim 1, wherein the slot control enables or disables a slot by allowing or preventing propagation of the standard memory and I/O read and write and chip select signals, ordinarily active to each slot on the control bus.

3. The plurality of switches of claim 1, wherein each switch comprises a dip switch assigned to each bus slot and wherein each dip switch is within a dip switch block accessible to the front panel of the computer.

4. The AT-only circuit board of claim 1, wherein the board contains addresses and wherein said addresses conflict with the standard peripherals required by the computer operating in the non-IBM-AT compatible mode.

5. An apparatus that controls a plurality of individual slots on an ISA compatible bus in a dual mode computer that selectively operates in either an IBM-AT compatible mode or a non-IBM-AT compatible mode, wherein the ISA compatible bus comprises a plurality of control signals for the slots, wherein each of said slots can receive a circuit board of a first compatibility type operative in both modes or a circuit board of a second compatibility type which only functions properly in the IBM-AT mode and which interferes with operation of the computer in the non-IBM-AT mode, said slots further adapted to receive master circuit boards of said first and second compatibility types which can control said bus, and wherein the computer has a mode signal which indicates whether the computer is operating in said IBM-AT mode or said non-IBM-AT mode, said apparatus comprising:

a respective configuration switch for each of said slots that generates a respective configuration signal that indicates the compatibility type of a respective circuit board within the slot;

a slot control circuit for each of said slots, said slot control circuit for a slot responsive to said mode signal and to the respective configuration signal for said slot to disable a plurality of bus control signal inputs and outputs to and from said circuit board in said slot in accordance with the compatibility type of said circuit board, said slot control circuit further responsive to a master signal to select a direction of propagation of said control signals through said slot control circuit appropriate to allow said master circuit board to assume control of said ISA bus.

6. The respective configuration switches of claim 5, wherein each switch comprises a dip switch assigned to a particular slot on the ISA bus.

7. An apparatus for automatically disabling each individual ISA bus slot in a dual mode computer that selectively operates in either an IBM-AT compatible mode or a non-IBM-AT operatively mode, wherein the dual computer has a mode signal indicating its mode of operation, said computer adapted to receive master circuit boards which can control said bus, said apparatus comprising:

a configuration signal for each slot that indicates whether the slot contains an ISA compatible circuit board which functions correctly in both modes or contains an ISA compatible circuit board which interferes with the operation of the computer in the non-IBM-AT compatible mode;

a slot controller for each slots responsive to the mode signal and the respective configuration signal to provide a slot control signal, said slot controller further responsive to a master signal to select a direction of propagation of said control signals appropriate to allow said master circuit board to assume control of said bus; and

a gate for each slot responsive to the respective slot control signal to selectively enable or disable propagation of a plurality of control signals to and from the ISA compatible circuit board installed in each slot.

8. The slot controller of claim 7, wherein the controller comprises a programmable logic array.

9. A dual mode computer which selectively functions in an IBM-AT compatible mode and a non-IBM-AT compatible mode, said dual mode computer including an Industry Standard Architecture (ISA) bus having a plurality of slots for receiving circuit boards therein, wherein said slots adapted to receive master circuit boards which can control said bus, said ISA bus including a control bus comprising standard memory and I/O read and write signals and chip select signals to control the operation of circuit boards in said slots of said ISA bus, said computer including an additional mode indication signal which indicates whether the computer is operating in said IBM-AT compatible mode or said non-IBM-AT compatible mode, comprising:

at least one single compatible circuit board connected to said ISA bus which functions properly in response to signals on said ISA bus when the computer is operating in said IBM-AT compatible mode and which functions improperly and interferes with the operation of the computer if enabled when the computer is operating in said non-IBM-AT compatible mode;

at least one dual compatible circuit board connected to said ISA bus which functions properly in response to signals on said ISA bus when the computer is operating in said IBM-AT compatible mode and which does not interfere with the operation of the computer if enabled when the computer is operating in said non-IBM-AT compatible mode;

a plurality of switches to configure each of said plurality of slots for either a single compatible circuit board or a dual compatible circuit board, each switch providing a respective slot configuration signal indicating whether a single compatible board is connected in that slot; and

slot control logic responsive to said mode indication signal and to said slot configuration signal to automatically enable or disable a slot so that said single compatible board is enabled only when the computer is operating in the IBM-At compatible mode and so that said dual compatible board is enabled when the computer is operating in the IBM-AT compatible mode and in the non-IBM-AT compatible mode, said slot control logic further responsive to a master signal to select a direction of propagation of said control signals appropriate to allow said master circuit board to assume control of said bus.