@ECHO OFF
REM DRVLIST.BAT - lists available drive letters
IF NOT '%1'=='' GOTO TEST_DRIVE
SET Drives=
ECHO Checking for drives a: through z:...
FOR %%v IN (a b c d e f g h i j k l m n o p q r s t u v w x y z) DO CALL %0 %%v
ECHO Available disk drives: %Drives%
GOTO End

:TEST_DRIVE
  REM>$$TEST$$.$$$
  %COMSPEC% NUL /F /C IF EXIST %1:\NUL DEL $$TEST$$.$$$
  IF NOT EXIST $$TEST$$.$$$ SET Drives=%Drives% %1:
  IF EXIST $$TEST$$.$$$ DEL $$TEST$$.$$$
:End