Abstract:
A method and system for resolving or preventing bus address conflicts between interface cards of a personal computer involves using a register instead of a switch to allow a user to select an address based on programming. When a conflict occurs between addresses of two interface cards, one of the interface cards may be re-addressed by re-programming the card with no need for manually setting a switch.

Description:
This application is a continuation of application Ser. No. 08/009,934, filed Jan. 27, 1993, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a method and system for resolving or preventing bus address conflicts between interface cards of a personal computer, by using a register instead of a switch for the purpose of address setting, thereby allowing a user to select an address based on programming such that when conflicts occur between addresses of two interface cards, the cards may be re-addressed by programming. In addition, a temporary register is provided to allow for verification and prevent writing of incorrect information in the address register or unintended resetting of other interface cards which could cause a malfunction and system crash. 
     DESCRIPTION OF THE PRIOR ART 
     Ordinary conventional bus interface cards of personal computers have their addresses set by a number of switches, but there are several drawbacks to such cards. 
     First, there are different ways used to set the address and a user can only understand its manner of setting by referring to a user&#39;s manual. 
     Second, when two interface cards have the same address setting, aa user must open the case of the personal computer and take out interface cards to reset them. 
     The aforementioned procedure is not only troublesome, but also offsets the advantages of convenience and time-saving which are the principal reasons for using a computer. Thus, the conventional method and system are in need of research and improvement. 
     It is accordingly the objective of the invention to overcome the drawbacks and inconvenience caused by the above described methods and apparatus for setting the bus addresses of interface cards for presently available personal computers. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a method and system for resolving or preventing but address conflicts between interface cards of a personal computer, by using a register instead of a switch setting to set the bus address, the address setting being stored in the register; and by controlling the content of the register using programming to enable a user to clearly select the address required according to a more user-friendly programming interface. 
     Further, the invention provides a method and system for resolving or preventing bus address conflicts between interface cards of a personal computer in which, when an address conflict occurs between two interface cards, a program can be used to alter the contents of a register by a serial read-out and shift the address of the interface card to a new address the necessity for manual switch setting. 
     Moreover, the invention provides a method and system for resolving or preventing bus address between interface cards of a personal computer which, instead of altering the contents of a register by directly writing the new address therein, checks whether the new address is intended for the address card to prevent writing an unintended address to the interface cards resulting in a system malfunction or crash. 
     The present invention will be understood more fully from the detailed description given below and from the accompanying drawings of the preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow chart showing the process steps for resolving or preventing bus address conflicts between interface cards of a personal computer according to the present invention. 
     FIG. 2 shows a system for resolving or preventing bus address conflicts between interface cards of a personal computer according to the present invention. 
     FIG. 3 shows simulated experimental results of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a flow chart showing process steps for resolving or preventing bus address conflicts between interface cards of a personal computer according to the present invention, in which there is no need to alter the content of a register by direct input, but rather involves first reading the contents of the register while storing the new address temporarily, as follows: 
     Step 1 involves, preferably, reading the register continuously for 5 times. If there is any other intervening action (such as, e.g., reading other registers or any write-in operation), the procedure is repeated from the beginning. 
     In step 2, the new address is read once and stored temporarily in the second register. 
     In step 3, the second register is successively read for 4 times. As in step 1, if any other actions intervene, the reset procedure is re-started. 
     In step 4, the old address is re-read and compared with the new address, and then the new address is stored in the address register to complete the operation of address alteration. 
     As depicted in FIG. 2, a system for resolving or preventing bus address conflicts between interface cards of a personal computer required to complete the above-described steps includes: 
     a normal signal source S, that provides a usual read or write instruction signal; 
     an address register AR, for temporarily storing a signal from signal source S and another signal from a register A; 
     a multiplexer M., which acts as a selectable switch for selectively allowing the passage of signals from address register AR and register A; 
     an address bus PA, which carries the address signal from personal computer; 
     register A, for temporarily storing an address signal received from address bus PA and transmitting it to multiplexer M or address register AR; 
     a comparator CMP, for receiving a data signal from multiplexer M, comparing it with the signal on the address bus PA and then outputting a signal indicating the comparison results to the counter CNT; and 
     a counter CNT, which connects to the output node of comparator CMP and is driven by the signal resulting from the comparison. 
     At the start of the operation of the system, the multiplexer M transmits a signal from the address register AR to the comparator CMP to compare it with the signal from the address bus PA, which should both be in the form of the current address. If they are alike, a pulse signal is sent to the counter CNT. If not, the counter CNT is cleared. When 5 successive pulse signals are counted by the counter CNT, the multiplexer M is switched to register A and then, at the time of next pulse, the data of the address bus PA is stored in the register A for comparison, the data on the address bus having been switched to the new address. Thereafter, when the comparator CMP operates 4 times upon detecting a match and the counter CNT counts to 4, the multiplexer M is switched back to the address register AR for the last comparison of the old (current) address with the old address again present on the address bus. Provided all comparisons are successful, the new address stored at the sixth cycle in the register A is written to the address register AR to replace the &#34;old&#34; or &#34;current&#34; address with the new address and thus the procedure for resetting the bus address of the card is completed. 
     It should be noted that a channel available for direct storage of an address in the address register AR is also conserved in the above said system and procedure. 
     FIG. 3 shows the results of a computer simulation of the invention, in which the abbreviations have the following meanings: 
     PA: an address bus 
     PIORB: a computer read-out signal 
     PIOWB: a computer write-in signal 
     PDL: a data bus 
     PROT. CNT.: a counting signal 
     PROT. LP: a signal for writing in a register A 
     PROT. SL: a multiplexer switching signal 
     Counter. 1: a counter 
     WRIAR: a signal written-in an address register. 
     In this example, when the address on bus PA is switched to 280, the bus address of the interface card of a personal computer is still set at the old address. After reading-out from the address register consecutively for 5 times, the switch signal PROT.SL is triggered. Then, when reading-out for the sixth time, the storing signal is activated and the signal is stored in the temporary register A. Thereafter, upon reading out for the eleventh time, the write signal WRIAR of the address register is triggered whereupon the address stored in register A is written to address register AR. 
     Although the present invention has been fully described by way of example, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention as defined by the appended claims, they should be construed as included therein.