He starts by writing dozens of bytes to check if the written bytes are correct or not (along with other side effects for bootstrapping), and some more to see th

He starts by writing dozens of bytes to check if the written bytes are correct or not (along with other side effects for bootstrapping), and some more to see the exact bytes to be written before applying them. And then finally 300+ actual bytes are written. Not as difficult overall, but initial steps would still require extreme patience.