Correct MFM controller card for miniscribe drive ?

[Hugo Holden]

I'm thinking of attempting to install a MiniScribe 3425-5-25 21MB MFM drive in a 5155 computer. I have both a Western Digital MFM drive card and an ST11M, will either of these work with the miniscribe drive ? or what is the correct controller card ?

 

[NeXT]

Either of them should work but you must perform a Low-Level format before letting DOS partition and format the disk for itself. How to do that is described in a few threads on the forum already.

 

[modem7]

I'm thinking of attempting to install a MiniScribe 3425-5-25 21MB MFM drive in a 5155 computer.

Of course, do not use slot 8.

I have both a Western Digital MFM drive card ...

A model number is required. For all we know, your card is one designed for AT-class computers.

.. and an ST11M, will either of these work with the miniscribe drive ?

Both ST11M and drive are "MFM".
The MiniScribe 3425 has the very common drive geometry of 615 cylinders and 4 heads, rated for 17 Sectors per track.
The "ST11M SUPPORTED DISK PARAMETERS" table shown at [here] has an entry for the above.
So, yes to the ST11M.

Step 1. Cable, terminate and set drive-select jumpers per [here].
Step 2. Low-level format per the "MISCELLANEOUS TECHNICAL NOTES" section at the bottom of [here].
Step 3. Partition and high-level format per [here].

 

[Hugo Holden]

Thanks modem7 for the helpful info.
The Western digital card I have is a WDXT-GEN2 Plus.

 

[modem7]

The Western digital card I have is a WDXT-GEN2 Plus.

The WDXT-GEN2 PLUS will work as well.

Note the general requirement in XT-class systems to redo the low-level format (followed by FDISK/FORMAT) whenever a hard drive is moved to a different controller.

Chapter 3 of the installation guide for the WDXT-GEN2 PLUS contains information on how to perform the low-level format for that controller.

Of the two low-level format options specified in the installation guide, jumper or dynamic configure, I recommend the latter. For that, the type string that you would enter for the MiniScribe 3425 is: 615 4 616 128 11 3

 

[Hugo Holden]

Thanks Modem7. I will set it up with the Western Digital controller first.
What is the reason that you recommend the dynamic configure option vs the jumpers ?
(one reason I'm wanting to try the miniscribe is that I have had intermittent read errors with my original st251 drive, so I bought a couple of other st251's. They were very badly packed for transit, just cardboard wrapped around them and dropped, one developed read errors right away, the other had shorted tant caps unrelated to the trauma, I fixed that, the drive seemed ok initially, low & high level formatted ok and then was suddenly unable to read some files. So hopefully if the minscribe drive arrives in good shape I will be in luck this time)

 

[vwestlife]

the drive seemed ok initially, low & high level formatted ok and then was suddenly unable to read some files.

Keep in mind these old stepper motor hard drives are temperature sensitive, so if you format and write data to the drive when it's cold and then try to read it when it's warm, you may get errors.

When I had a Tandy 2000 HD it came with a big orange sticker on it saying to wait half an hour before low-level formatting the hard drive to let it fully warm up, so I've always followed that advice. Whenever I use a vintage computer with a stepper motor hard drive, I always let it warm up (at least 10 - 15 minutes) before doing any work that involves writing data to the drive.

 

[Hugo Holden]

Thanks vwestlife, that is very interesting. I probably plugged it up and formatted it right away, it could explain why it appeared to malfunction after it had been running for a while and heated up.

 

[modem7]

Thanks Modem7. I will set it up with the Western Digital controller first.
What is the reason that you recommend the dynamic configure option vs the jumpers ?

Table B1 in the installation guide for the WDXT-GEN2 PLUS list the drive geometries that are supported by the jumper option.
Your drive (614 cyls / 4 heads) is there, but nothing about the WPC that will be used, or about what step rate the controller will be used.
We can ignore WPC in a hobby environment, so what remains is an unknown step rate.
Chances are that whatever it is, is probably going to be okay for the MiniScribe 3425.

But I prefer to avoid unknowns, and the dynamic configuration functionality of the WDXT-GEN2 PLUS gives us complete control: cylinders / heads / RWC / WPC / step rate.
That is why I see dynamic configuration (for the WDXT-GEN2 PLUS) as the preferred option.

 

[Hugo Holden]

Thanks modem7, that is very good, I prefer to avoid unknowns too.

 

[modem7]

Thanks modem7, that is very good, I prefer to avoid unknowns too.

BTW. The WD dynamic configure string of "615 4 616 128 11 3" that I quoted for the MiniScribe 3425 is based on the information on pages 1 and 2 (PDF pages 3 and 4) of the MiniScribe manual at [here].

"616" = RWC cylinder [no RWC, so this value is set to "total cyls. + 1" per MiniScribe manual]
"128" = WPC cylinder
"11" = max. correctable error burst length of 11 bits
"3" = CCB option byte of 3

 

[Hugo Holden]

Thanks kindly for the help modem7, I will pay attention to your advice. The vintage computer forum has been of great help to me with my 5155 computer, working through various problems, and you are a credit to the forum.