I think Undies~ has it?

BUT.. in some the Horizontal is a blank or no connection.. in other words a nice way of keeping the jumpers in a safe place..
With some of the older drives there were more options as I recall............I am talking 52Mb to 512Mb drives here

The sideways position I have only seen as being "blank" which was for a drive that was the master and ONLY drive on the system. There were other settings for master in a master slave situation and so on. I have even got some that have two jumpers. You used the sideways setting to keep the redundant one safe.





EDIT: Just had a "flashback"..................this was a source of problems back then. Western Digital used to use this sideways setting for "single", as in one drive that is the master by definition. Their drives shipped for a while with this as the default. Everyone else tended to use cable select. If you just installed the WD drive in a system that was cable select, it would not work.

Something along those lines anyways..............I havent seen the problem for years now