var
Letra: Char;
OldErrorMode: word;
begin
OldErrorMode:= SetErrorMode(SEM_FAILCRITICALERRORS);
try
for Letra:= 'C' to 'J' do
begin
if GetDriveType(Pchar(Letra+':\')) = DRIVE_REMOVABLE then
begin
If FileExists(Letra+':\prueba.txt') then
ShowMessage('Tengo la SD, ahora sincronizo');
end;
end;
finally
SetErrorMode(OldErrorMode);
end;
end;