//=======================================================================
// Copyright Baptiste Wicht 2013-2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================

int main(){
    asm volatile("int 50");

    return 1;
}
//=======================================================================
// Copyright Baptiste Wicht 2013-2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================

typedef unsigned int uint8_t __attribute__((__mode__(__QI__)));
typedef unsigned int uint16_t __attribute__ ((__mode__ (__HI__)));
typedef unsigned int uint32_t __attribute__ ((__mode__ (__SI__)));
typedef unsigned int uint64_t __attribute__ ((__mode__ (__DI__)));

uint8_t make_color(uint8_t fg, uint8_t bg){
    return fg | bg << 4;
}

uint16_t make_vga_entry(char c, uint8_t color){
    uint16_t c16 = c;
    uint16_t color16 = color;
    return c16 | color16 << 8;
}

int main(){
    uint16_t* vga_buffer = reinterpret_cast<uint16_t*>(0x0B8000);

    vga_buffer[10 * 80 + 40] = make_vga_entry('1', make_color(15, 0));

    return 0;
}
--- 
+++ 
@@ -5,25 +5,8 @@
 //  http://www.boost.org/LICENSE_1_0.txt)
 //=======================================================================
 
-typedef unsigned int uint8_t __attribute__((__mode__(__QI__)));
-typedef unsigned int uint16_t __attribute__ ((__mode__ (__HI__)));
-typedef unsigned int uint32_t __attribute__ ((__mode__ (__SI__)));
-typedef unsigned int uint64_t __attribute__ ((__mode__ (__DI__)));
+int main(){
+    asm volatile("int 50");
 
-uint8_t make_color(uint8_t fg, uint8_t bg){
-    return fg | bg << 4;
+    return 1;
 }
-
-uint16_t make_vga_entry(char c, uint8_t color){
-    uint16_t c16 = c;
-    uint16_t color16 = color;
-    return c16 | color16 << 8;
-}
-
-int main(){
-    uint16_t* vga_buffer = reinterpret_cast<uint16_t*>(0x0B8000);
-
-    vga_buffer[10 * 80 + 40] = make_vga_entry('1', make_color(15, 0));
-
-    return 0;
-}
Modify one to use system call
