It is impossible only to set a printer to print a character rotated by 90 degrees.

It is the same as an ink jet or high specification printer. The different sizes of paper in the longitudinal and lateral dimensions make it impossible to rotate a character.

 

Windows driver enable to rotate a character by 90 degrees to select lateral directions on an application.

Windows generates data to make paper rotated and the driver print it. (Rotated characters become graphic.)

 

If an application generates printing data, a character is rotated by 90 degrees with a printer's command. A command which rotates each character by 90 degree causes to disturb the order in the transmission and printing sequence.

 

For example, if you print

ABCDEF

321abc

which are rotated by 90 degree all together, you need each character is rearranged the order as 3A 2B 1C aD bE cF.
It is too difficult to arrange characters appropriately.

 

There is a command rotating all characters together which is called a page mode function. The function makes it easier to arrange data, but more difficult to use the command.

Refer to chapter 5.1 of the command reference for detail.