init

projects/04/fill/Fill.asm

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/04/Fill.asm
+
+// Runs an infinite loop that listens to the keyboard input.
+// When a key is pressed (any key), the program blackens the screen,
+// i.e. writes "black" in every pixel;
+// the screen should remain fully black as long as the key is pressed. 
+// When no key is pressed, the program clears the screen, i.e. writes
+// "white" in every pixel;
+// the screen should remain fully clear as long as no key is pressed.
+
+// Put your code here.
+
+@SCREEN
+D=A
+@PTR
+M=D
+
+(WHITE)
+@KBD
+D=M
+@BLACK
+D;JNE
+
+@SCREEN
+D=A
+@PTR
+M=D
+
+(WLOOP)
+@PTR
+D=M
+@R0
+M=D
+@KBD
+D=A
+@R0
+D=D-M
+@WHITE
+D;JEQ
+
+@PTR
+A=M
+M=0
+
+@PTR
+M=M+1
+
+@WLOOP
+0;JMP
+
+(BLACK)
+@KBD
+D=M
+@WHITE
+D;JEQ
+
+@SCREEN
+D=A
+@PTR
+M=D
+
+(BLOOP)
+@PTR
+D=M
+@R0
+M=D
+@KBD
+D=A
+@R0
+D=D-M
+@BLACK
+D;JEQ
+
+@PTR
+A=M
+M=-1
+
+@PTR
+M=M+1
+
+@BLOOP
+0;JMP

projects/04/fill/Fill.tst

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/04/fill/Fill.tst
+
+load Fill.asm;
+echo "Make sure that 'No Animation' is selected. Then, select the keyboard, press any key for some time, and inspect the screen.";
+
+repeat {
+  ticktock;
+}

projects/04/fill/FillAutomatic.cmp

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+|RAM[16384]|RAM[17648]|RAM[18349]|RAM[19444]|RAM[20771]|RAM[21031]|RAM[22596]|RAM[23754]|RAM[24575]|
+|       0  |       0  |       0  |       0  |       0  |       0  |       0  |       0  |       0  |
+|      -1  |      -1  |      -1  |      -1  |      -1  |      -1  |      -1  |      -1  |      -1  |
+|       0  |       0  |       0  |       0  |       0  |       0  |       0  |       0  |       0  |

projects/04/fill/FillAutomatic.tst

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/04/fill/FillAutomatic
+
+// This script can be used to test the Fill program automatically, 
+// rather than interactively. Specifically, the script sets the keyboard
+// memory map (RAM[24576]) to 0, 1, and then again to 0. This simulates the 
+// acts of leaving the keyboard untouched, pressing some key, and then releasing
+// the key. After each on of these simulated events, the script outputs the values
+// of some selected registers from the screen memory map (RAM[16384]-RAM[24576]).
+// This is done in order to test that these registers are set to 000...0 or 111....1, 
+// as mandated by how the Fill program should react to the keyboard events.
+
+load Fill.asm,
+output-file FillAutomatic.out,
+compare-to FillAutomatic.cmp,
+output-list RAM[16384]%D2.6.2 RAM[17648]%D2.6.2 RAM[18349]%D2.6.2 RAM[19444]%D2.6.2 RAM[20771]%D2.6.2 RAM[21031]%D2.6.2 RAM[22596]%D2.6.2 RAM[23754]%D2.6.2 RAM[24575]%D2.6.2;
+
+set RAM[24576] 0,    // the keyboard is untouched
+repeat 1000000 {
+  ticktock;
+}
+output;              // test that the screen is white
+
+set RAM[24576] 1,    // a keyboard key is pressed
+repeat 1000000 {
+  ticktock;
+}
+output;              // test that the screen is black
+
+set RAM[24576] 0,    // they keyboard in untouched
+repeat 1000000 {
+  ticktock;
+}
+output;              // test that the screen is white
+