Inserted provided code to 01_gdb kernal.c

Part2/A4/01_gdb/kernel/kernel.c

@@ -5,4 +5,25 @@ void dummy_test_entrypoint() {
 void _start() {
 	char* video_memory = (char*) 0xb8000;
 	*video_memory = 'X';
+    unsigned char a;
+    unsigned char b;
+    a = 0;
+    b = 0;
+    for( int i = 1; i < 24; ++i) {
+            for( int j = 0; j < 80; ++j) {
+            *(video_memory + i*160 + j*2) = '.';
+            }
+    }
+
+    *video_memory = 'Z';
+    for( int i = 10; i < 20; ++i) {
+            for( int j = 50; j < 60; ++j) {
+            *(video_memory + i*160 + j*2) = 'X';
+            }
+    }
+    while( 1) {
+            *(video_memory+0) = b;
+            *(video_memory+1) = ++a;
+            b = b + a/255;
+    }
 }