Question

Write down the procedure for fetching a word from the memory

Answer 1

Data is generally transferred between registers in the CPU and memory cells. When you want to fetch a word from the memory, it depends on the implementation of that particular process architecture.

When your input is of variable length, then you can fetch one word in every fetch cycle. After your fetch the word you need to decode.

If you are requirement is more than one word, then it is repeated using the execution cycle.

For example when you input is 2 words which is of a fixed length, you can fetch two words from the memory instead of one in a fetch cycle.

Answer 2

Answer:

To fetch a word from memory the processor has to specify the address of the memory

Then the processor has to request a read operation.

After requested data received from memory the data is stored in MDR

Connection of MDR is shown in the figure below:

memory read operation requires three steps:

1. R 1 out, MAR in, Read
2. MDR in E, WMFC
3. MDR out, R2 in

where WMFC wait for memory function to be completed.