[CentOS] how can I tell what's on the MBR of /dev/sda?

> I would like to find out if I have anything written on the MBR of a disk 
> in my system /dev/sda, or any other device.
> If there is something there, is it readable, or recognizable to humans?

sudo dd if=/dev/sda bs=512c count=1 | hexdump -C

-- 

rgds
Stephen