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memorycpu-architecture

is the address bus indicate the size of the address in ram?

I'm sorry for such simple question but this question borders me. so as exp we have the address bus 20 bits.

Does this imply that the address in ram should have 20 bit as size and if the data bus has 16 bits the value in ram are code 16 bit?

Solution

  • The address bus indicates the size of addressable items, including ram, bios, video ram, any I/O mapped devices, ... . The data bus indicates how many bits can be transferred at a time.

    20 bits would be 1 MB of address space. However, an external chip to support extended memory could be used to allow more ram. I recall an embedded device (tape drive from the 1980's) that used an 80186, with a custom extended memory interface to support more than 1MB of ram.