Hello, and welcome to the forum!
there are two ways to run machine language programs in DragonDOS. The first, using your example of RACER.BIN, is
the second, and perhaps more convenient method, is
Note that for BASIC programs (those with a .BAS extension) there is no need to include the extension and for the first method RUN is used instead of EXEC. For example, for the program RACER.BAS use either
Furthermore, some discs are bootable. For these discs use
(if you get a "?BT ERROR" then you will know that the disc is not bootable and you will have to use one of the above methods).