System and method for testing and remapping base memory for memory diagnostics

In a computer system including a microprocessor providing a paging function, a method for testing a first memory bank containing base memory in which resides at least an operating system for the computer system, said method comprising the steps of:

• (i) initiating operation of said operating system out of said base memory in said first memory bank by disabling the paging function of said microprocessor;
• (ii) defining a mapping scheme, by initializing a page directory within microprocessor-controlled memory, which establishes a correspondence between physical addresses in said first memory bank and in a second memory bank, and logical addresses which map to said physical addresses in said first and second memory banks, wherein a defined logical address for said base memory in said first memory bank is mapped to a physical address in said second memory bank;
• (iii) copying the contents of said base memory from said first memory bank to said second memory bank;
• (iv) switching operation of said operating system from said base memory in said first memory bank to said contents of said base memory copied in said second memory bank, by enabling said paging function of the microprocessor and accessing said copied contents of said base memory using said defined logical address;
• (v) performing a memory test on said first memory bank using a memory diagnostic program;
• (vi) re-copying said copied contents of said base memory from said second memory bank back into said first memory bank;
• and
• (vii) switching operation of said operating system from said copied contents of said base memory in said second memory bank to the re-copied base memory in said first memory bank.

In a computer system, a memory test apparatus for on-line testing a first memory bank containing base memory in which resides at least the memory test apparatus and an operating system for the computer system;

• said apparatus comprising a memory diagnostic program including means for:
• (i) initiating operation of said operating system out of said base memory in said first memory bank in a first mode of operation;
• (ii) defining a mapping scheme with a microprocessor in the system which establishes a correspondence between physical addresses in said first memory bank and in a second memory bank, and logical addresses which map to said physical addresses in said first and second memory banks;
• wherein (i) a defined first logical address range for said base memory in said first memory bank is mapped to a first physical address range in said first memory bank in said first mode of operation and is mapped to a second physical address range in said second memory bank in a second mode of operation;
• and (ii) a defined second logical address range in said first memory bank is mapped to said second physical address range in said first mode of operation and is mapped to said first physical address range in said second mode of operation;
• (iii) copying the contents of said base memory from said first physical address range in said first memory bank to said second physical address range in said second memory bank;
• (iv) switching operation of said operating system from said base memory in said first memory bank, in said first mode of operation, to said contents of said base memory copied in said second memory bank, in said second mode of operation, by accessing said copied contents of said base memory using said defined logical address;
• (v) performing a memory test on said first memory bank using the memory diagnostic program;
• (vi) re-copying said copied contents of said base memory from said second memory bank back into said first memory bank;
• and
• (vii) switching operation of said operating system from said copied contents of said base memory in said second memory bank, in said second mode of operation to the re-copied base memory in said first memory bank, in said first mode of operation.