ST506 Interface "Direction In" Pin # 34 on the 34-pin connector

19 views
Skip to first unread message

Convergent MightyFrame

unread,
Mar 13, 2021, 10:54:14 PMMar 13
to MFM Discuss
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!

Best,
AJ

David Gesswein

unread,
Mar 14, 2021, 8:16:58 AMMar 14
to mfm-d...@googlegroups.com
Dir in is the direction pin. It should be changing state if its seeking
in both directions.

Your previous capture AWS-CM5616 - Boot 3.logicdata shows the signal changing.

Convergent MightyFrame

unread,
Mar 14, 2021, 5:51:00 PMMar 14
to MFM Discuss
David,

Clearly you are right...thanks for straightening out my confusion here!  

Best,
AJ

Reply all
Reply to author
Forward
0 new messages