Patent ID: 6601130
Filing Date: 2003-07-29
Classification: G06F,G11C

Abstract:
A memory interface unit for coupling a microprocessor to a memory external to the microprocessor, said memory being provided in the form of a plurality of memory banks, each of the memory banks being provided with address lines and data lines, at least a first memory bank of the plurality of memory banks being of a first type which is directly addressable, which first memory bank has a chip select input for selecting the first memory bank, and a second memory bank of the plurality of memory banks being of a second type, which is addressable by a row address and a column address, the row address being validated by a row address strobe at a row address strobe input of the second memory bank, and the column address being validated by a column address strobe at a column address strobe input of the second memory bank, said memory interface unit comprising:address selection means for receiving a first address corresponding to the first memory bank, a second address corresponding to the second memory bank, and a bus arbitration signal indicating which of the first address and the second address is to be selected; and unique strobes for each of the plurality of memory banks, which unique strobes are programmable in dependence of a type of memory bank to which a particular unique strobe relates, a first strobe of the unique strobes being programmed as a chip select signal which is inputted to the chip select input of the first memory bank, and a second strobe of the unique strobes being programmed as the row address strobe inputted to the row address strobe input of the second memory bank; wherein the first memory bank is of non-volatile type in which executable code is stored including boot up code, and after execution of the boot up code at a microprocessor reset the executable code is moved from the first memory bank to the second memory bank; and wherein after moving the executable code the first and second memory banks are swapped so that the executable code is executable from the same base address as before swapping.