This is more of a general ST506 question, but one I can't find a good answer for anywhere else.
Pin #24 is step, which steps the head position on the drive. But, Direction In never has any signals when I test. How does the head know which direction to "step" without this direction signal?
"The control card translates requests for a particular track and sector
from the host system into a sequence of head positioning commands,
including setting the direction of head movement, in or out, and sending
individual "STEP" commands to move. Four of the control cable pins,
"HD SLCT 0" through "HD SLCT 3", allow the selection among up to 16
heads, although only four are available on the two-platter ST506."
This makes it sound like somehow the head select lines determine the step direction, instead of the "Direction In" pin.
Can anyone help clarify this for me?
Thanks again to all!