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\(4.6.\)Working with register and memory

1.Operations towards D

  • Storing value: It turns out that there's no direct way to do it, we have to do it indirectly. For example, if we want to store 10 in register D: 

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    @10
    D = A

  • Incresing value: We can use C instructions directly: 

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    D = D + 1

  • Setting D to RAM value: It's similar to storing value: 

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    @10
    D = M

2.Usage of D register

  D register is of great importance in assignment operations: 

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//set RAM[10] to 5
@5
D = A
@10
M = D

//set RAM[10] to RAM[5]
@ 5
D = M
@10
M = D

3.Built-in symbol