I started to learn assembler for the C64. Assembler for the 650x CPUs is easier to
learn than assembler for the x86 CPUs. They have less registers and instructions. I wouldn’t learn assembler to use it on the PC, that would be a waste of time, but I ordered a video game console and assembler on small systems is a good choice.
Most cross-assemblers just produce a memory dump of the compiled source, so I wrote this conversion programm. Inserting the two bytes everytime before the start of the programm was just too tedious 
.
#include <iostream>
#include <cstdlib>
#include <fcntl.h>
using namespace std;
/*******************************************
*This programm converts the output file of*
*a 650x (cross) assembler *
*to a PRG file suitable for C64 emulators *
*******************************************/
int main(int argc, char *argv[])
{
if (argc!=2){
cout<<argv[0]<<" FILE"<<endl;
exit(1);
}
FILE * pFile;
pFile = fopen (argv[1],"rb");
if (pFile!=NULL){
long lSize;
char * buffer;
// obtain file size.
fseek (pFile , 0 , SEEK_END);
lSize = ftell (pFile);
rewind (pFile);
// allocate memory to contain the whole file.
buffer = (char*) malloc (lSize+2);
if (buffer == NULL) exit (2);
// copy the file into the buffer.
fread (buffer+2,1,lSize,pFile);
fclose (pFile);
char start[2];
char end[2];
start[0]=buffer[2];
start[1]=buffer[3];
end[0]=buffer[lSize];
end[1]=buffer[lSize+1];
if(end[0]&start[0]==end[0]&&end[1]&start[1]==end[1]){
cout<<"File is already in PRG format."<<endl;
exit(1);
}
buffer[0]=end[0];
buffer[1]=end[1];
pFile = fopen (argv[1] , "wb");
fwrite(buffer,1,lSize+2,pFile);
}
return EXIT_SUCCESS;
}
