Does a Seagate ST-225 require a data separator ?

[retrogear]

I'm trying to get a hard drive running on my ADC Super Six setup. I have a Monitor Dynamics HDC-1013 controller trying to interface with a Seagate ST-225 drive. The MD card has a data separator piggybacked on it. I assembled a test program provided by MD and get correct responses from the controller but when I attempt a format it goes thru the motions and the drive
makes the correct sounds but after a few minutes when it finishes and starts to verify basically nothing was written and it errors out. There is directions in the MD manual how to remove the
data separator and bypass it. How do you tell if a hard drive needs the separator ?

Larry G

 

[Chuck(G)]

Yes, it's a standard ST506/ST412 interface drive. Do check JP7, pins 5 and 6 to make sure there's no jumper there.

 

[Oldcoder]

That depends upon which ST225 you are referring to. Seagate produced 2 variants of the 225: ST225N which is a SCSI drive and includes the controller and data separator and the standard MFM ST506/ST412 i/f version that requires an external controller and data separator.

Peter

 

[Chuck(G)]

Somehow, I don't think that the S100 HDC-1013 supported SCSI drives...

 

[retrogear]

Interestingly one of my Seagate ST-225's has a piggyback card with a 50 pin cable but it's model shows 225 not 225N. Also my MD HDC1013 S100 card has a place for a 50 pin header but it wasn't ever soldered in. My understanding is that would be SASI ? Right now I'm just trying to prove I have a good hard drive using an IBM PC but I'm waiting for a controller for that. My IBM 5150 has an original IBM 10MB only controller and hard drive which works great. I also have an 8bit ISA WD controller which doesn't seem to work. I am getting another ST-225 and ISA controller today. I also just bought an XT-IDE with a 64MB CF which is on it's way. I'm determined to make something happen even though I'm spending too much money. I threw too much away many years ago in a house move. Damn, I even bought an IBM AT motherboard and a 16 bit ISA IBM MFM controller. Ebay is lovin' me, I need professional help about now ...

Larry G

 

[Chuck(G)]

Probably not SASI, given the time period. Early drives like the 8" Shugart SA-1000 used a 50 conductor control cable in addition to the regular 20 conductor differential signal cable.
If you look at the 14" SA-4000 you have not only the 50 pin cable, but the option for on-board data separator (hence the option on your controller).

 

[retrogear]

Just to follow up on this, I proved I had a functional ST-225 by using an MFM controller on my IBM 5150 so I moved it to my ADC Super Six S100 contraption attached to the Micro Dynamics HDC-1013 Winchester S100 card with it's data separator and assembled their test utility MDTEST to format it 32 sectors/track 256 bytes/sector, then used it to calculate and write a disk parameter block (DPB) to one of the 1st sectors for TurboDOS (it offered the option for CP/M as well). I gen'd an OSMASTER.SYS for my 8" floppy with an MDTURBO driver for C: and damn, it worked !! I now have a 20MB TurboDOS drive for my Super Six !! Time to celebrate ...

Larry G

 

[Chuck(G)]

Congratulations!

It's really a shame that the information about pre-PC "small" hard disks is being forgotten by the collective memory. I guess it goes along with the thinking that anything with a 50 pin connector must be SCSI. I remember this being a legendary eBay failure when identifying QIC-02 or QIC-36 tape interface boards.

My first 5150 hard disk was a Shugart SA-1000; all 4 MB of it. I still have a big SA-4004 drive sitting in my shop. Haven't powered it in ages--it draws quite a bit of AC current to get those platters spinning...

 

[Al Kossow]

all of the manuals are there on bitsavers, all that is required is for people to connect the dots

 

[retrogear]

Here's a youtube demo of the system in action. I have 8" floppies A and B, 5.25 floppies C 96tpi and D 48tpi with hard drive E. Floppy D is 48 tpi so I can transfer files in from a pc running 22disk with definition ADV5.

https://youtu.be/hU10bZ3igVM

Larry G

 

[retrogear]

I bought an ST225 controller card on ebay from the Czech Republic for $20 and it showed up today. I installed it on a 2nd hard drive that had refused to format and it works now and low level formatted with no media errors !! I'm beginning to think problems with old hard drives are just as likely to be electronic and not with the heads or platters. I'm on a roll !!!

Larry G