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ESDI Question

R

rheffera

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Jan 5, 2014
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Location
Adelaide, South Australia, Australia
I tried searching all over here and google but i have been unable to get solid answers.
Are ESDI drives backwards compatible with ST506 Controllers?
Wikipedia says so, but im not so sure

I have a DCT5150X - 8-bit ST506 controller.

I have 3 drives.
ST-225 - Works flawlessly w/ this controller.
NEC D3661 & D5665 - ESDI drives. Pulled frim single drive systems.

I am trying to verify the functionality of the NEC drives. (Both spin up)
I am unable to get the controller to pick up on them.

1701(20) from the controller bios, but i'd expect this from switching the drive on it.
Debug utility shows drive not present or not ready.

I am not convinced that these drives are dead. Perhaps im Setting up the drives wrong, or as i suspect, i need a ESDI controller.

Drive settings as found: DS2=ON, terminating resistors = all on. Rest are off
 
I believe you will need an ESDI controller to check the NEC drives. I don't know of an 8 bit ESDI controller, but there may have been some made. I had enough trouble getting my hands on a 16 bit controller to check the two ESDI drives I have.
 
Ryan Hefferan said:
I have a DCT5150X - 8-bit ST506 controller.

I have 3 drives.
ST-225 - Works flawlessly w/ this controller.
NEC D3661 & D5665 - ESDI drives. Pulled frim single drive systems.
Click to expand...
Could you possibly mean... DTC5150X for the controller and D5655 for the second drive? If so, you should realize that it's not very helpful to give us incorrect part Nos. when you're looking to resolve a problem. It only complicates the matter. :)

As fatwizard indicated, You need an ESDI controller for an ESDI drive, not an MFM controller which is what you're trying to use.
 
Ryan Hefferan said:
I tried searching all over here and google but i have been unable to get solid answers.
Are ESDI drives backwards compatible with ST506 Controllers?
Wikipedia says so
Click to expand...

Wikipedia is wrong.
ESDI has the read data separator on the drive and not the controller so the read data on the 20 pin connector
is completely incompatible.
I just re-read the ESDI spec, and there was a "step mode" which was compatible with the
ST412 34 pin connector, but I don't know how many drives supported it.

specs at http://bitsavers.org/pdf/cdc/discs/77738076-D2_ESDIspec.pdf
and
http://bitsavers.org/pdf/micropolis/ESDI_spec_X3.170-90.pdf
 
Everybody above is correct. ESDI is whole different protocol and you should not attempt to connect a ST506-interface controller to an ESDI drive. It won't work.

Software-wise, the closest thing to ESDI is IDE--IDE simply moved the controller onto the drive and exposed an AT-bus as the interface.
 
Stone said:
Could you possibly mean... DTC5150X for the controller and D5655 for the second drive? If so, you should realize that it's not very helpful to give us incorrect part Nos. when you're looking to resolve a problem. It only complicates the matter. :)

As fatwizard indicated, You need an ESDI controller for an ESDI drive, not an MFM controller which is what you're trying to use.
Click to expand...

Yeah, sorry about the typos :)

http://en.wikipedia.org/wiki/Hard_disk_drive_interface

In the table it lists ESDI as backwards compatible.

I Didn't believe the two were compatible anyway, i just wasn't sure as back in the day i went from MFM to IDE.

Thank you all for clearing it up. Now to get a hold of a ESDI controller. Im looking at a WD1007a-WA2
 
I think I asked a few years ago if there were an 8-bit ESDI controller. I think the consensus was that there wasn't.

But this tidbit comes from my decaying wetware.
 
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