ADDING MEMORY CHIPS TO MICRO PROCESSORS
here we deal with requirement of memory chip,then build a model and match the requirement with the micro-processor bus concepts;
here the steps
1.A memory chip require address lines to identify the a memory register.The number of address lines required is determined by the number of register in a chip ( 2^n=number of register where n is the number of address line ) the 8085 micro-processors have 16 address line .of these 16 lines , the address lines necessary for the memory for the memory chip must be connected to the memory chip.
2.A memory chip require a chip select ( CS bar) signal to enable the chip . the remaining adderss line of the micro processor can be connected to CS bar signal through an interfacing logic.
3.the address lines connected to CS bar select the chip,and the address lines connected to the the address line of the memory chip select the register. thus the memory address of a register is determined by the logic level of all the address lines .
4. the control signal read ( RD bar) enable the output buffer , and data from the selected register are made available on the out put lines. similarly the control signal write ( WR bar ) enable the
the input buffer, and data on the input lines are written into memory cells. The micro-processor
can use its memory read and memory write control signals to enable the buffer and the data bus to transport the content of the the selected register between the micro processor and memory.
........Labels: Micro-Processors