Rom Builder. by C.J.Richardson. C.J.Richardson. for Use the cursors to scroll up and down. Rom Builder is a program designed to enable you to insert machine code routines into ROM. To test the program Just run it, then press CONTROL and BREAK. Now type *BEEP. You should hear the equivalent of VDU 7. Now type MODE 0. Then type *MODE.You should now be in mode 7. These are the two routines already in the rom program. To see them, look at line 230 of the program. These are the commands that you enter. Line 250 contains the name of the routine associated with the command. The routines start at 260. It is only a simple matter to add to or alter the existing commands to insert your own routines.