Hi,
I'm working through some questions in a textbook on memory systems, and the question asks: "A memory system made of 4 64k by 16-bit memory blocks is connected to a 24-bit address. Make a design for a full address decode circuit, so the memories are arranged at consecutive addresses, starting at 0".
The problem is, as I understand it, that you need 18 address bits (A0-A17) common to each chip, and then you need 2 address lines into a 2-4 line decoder to select the right row (A22-A23).
That leaves A18-A21 unconnected. I emailed my lecturer and he said that this wasn't acceptable as a range of address values would activate the memory, and the unconnected bits must be connected into the decode logic to make sure that unique address values will activate the memory.
Any help is much appreciated.
I'm working through some questions in a textbook on memory systems, and the question asks: "A memory system made of 4 64k by 16-bit memory blocks is connected to a 24-bit address. Make a design for a full address decode circuit, so the memories are arranged at consecutive addresses, starting at 0".
The problem is, as I understand it, that you need 18 address bits (A0-A17) common to each chip, and then you need 2 address lines into a 2-4 line decoder to select the right row (A22-A23).
That leaves A18-A21 unconnected. I emailed my lecturer and he said that this wasn't acceptable as a range of address values would activate the memory, and the unconnected bits must be connected into the decode logic to make sure that unique address values will activate the memory.
Any help is much appreciated.