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Status: Tags: Links: HACK Programming

HACK Registers and Memory

Registers

D: Data Register

• D cannot be directly set, so we have to set D = A
  • But, D can be directly adjusted

A: Address/Data Register

• Be sure to differentiate between setting D and setting M
  • ex) @15 (D) vs @R15 (M) M: The Currently Selected Memory Register (M=RAM[A])

Random

• Whitespace and comments are ignored
• To prevent hackers from exploting code, it’s a good idea to keep things in an infinite loop

Symbols

• R (0..15)
• SCREEN (16384)
• KBD (24576)

Examples of Register Manipulation

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 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

// D=10
@10
D=A

// D++
D=D+1

//D=RAM[17]
@17
D=M

// RAM[17]=0
@17
M=0

// RAM[17]=10
@10
D=A
@17
M=D

// RAM[5]=RAM[3]
@3
D=M
@5
M=D
___
References: