INTERNAL COMMAND OF DOS

during boot-up computer reads dos system files froms the dos system disk. In this process, internal command are loaded in memory (ram). These command reside in memory as long as computer remains on. When computer power is switched off , these commands vanish from the memory.

When an internal command is executed(i.e. it is issued from the key board at the dos prompt and enter key is pressed), computer reads the command directly from ram to perform the task. Since these commands reside in ram, they are also called ram – resident commands.