10 Apr
2007
10 Apr
'07
12:10 a.m.
On 9 Apr 2007 at 9:42, Philip Pemberton wrote:
I think I've found the problem though - good
ol' drive select issues. Based on
the pinout I had, I expected that I'd have to activate /MOTEN_A (pin 10) and
/DRVSEL_A (pin 14) to get the drive to spin and output data. That assumption
was wrong - the drive wants pin 16 (/MOTEN_B according to my pinout) low, and
either /DRVSEL_A or /DRVSEL_B low depending on how the drive is jumpered.
I think I know what your problem is. You've been getting your
information off that great propoganda-machine, the World-Wide-Web.
No kidding; it's downright amazing how few sites have real
information and the remainder just parrot them, falsehoods and all.
There is no such signal as MOTEN_B. There is but a single motor
enable pin for all drives and it's pin 16. The web sites seem to get
the PC end of a floppy connector mixed up with the drive end. Here's
an "honest" pinout list for a drive:
2 /DCD Disk Change Detect/Density Select (depends on jumper)
4 /DS3 Device Select 3.
6 NC
8 /INDEX Index
10 /DS0 Device Select 0
12 /DS1 Device Select 1
14 /DS2 Device Select 2
16 /MTRON Motor On
18 /DIR Direction
20 /STEP Step
22 /WDATA Write Data
24 /WGATE Write Gate
26 /TK00 Track 0
28 /WRPT Write Protected
30 /RDATA Read Data
32 /SIDE1 Head Select
34 /RDY Ready or /DCD (depends on jumper)
Odd pins are common GND.
There are some exceptions to the above. Some NEC drives, in
particular, define some signals differently.
If you examine the above drive pinout, you will immediately
understand why IBM went with the "twisted" drive cable. It was not
so every drive could be set to DS1, but rather so that the motor on
each drive could be individually controlled. Some DTC hard disk
controllers flout this convention and allow for 4 drives on a single
"straight through" cable, and run the motors on all drives at the
same time.
Cheers,
Chuck