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Help with ST-11R disk controller

N

nunoalex

Member
Joined
Jun 16, 2023
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38
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Portugal
Hello everyone

I have a Seagate ST-250R hard drive and got the information that this is actually a drive for RLL encoding and not an MFM
So I searched around and came to the knowledge that the best controller for this drive is the ST-11R since this drive uses some special 31 sectors per track or so and many controllers dont support this feature.

I got my hands on a ST-11R but there seems to be a problem since the BIOS utility the card only shows me a handful of MFM type drives as possible choices.. no "R" drive is available.

Using the "debug" command in DOS the ROM BIOS utility gave me 6 possible drive types to use and I ended up formatting the drive as a ST-225 which it did fine ... the drive now boots fine with DOS 5.0 and has 20MB.

My question is.. did I buy the wrong controller ? is this a ST-11 and not an ST-11R ? I thought there existed only one controller
On the card there are two ROM chips one has a saying "ST-11" and the other chip says "ST-11R microcode" so to the best of my knowledge there is some "R" into it

The board has absolutely no jumpers except the ROM start address and that doesn't seem to have any influence

Can someone with knowledge in this type of technology help ?
The controller technical manual from seagate there is around always seem to give the idea that there is only one single type of controller that is called "ST-11M/ST-11R"
I will post a picture of the controller asap

Thank you

Nuno
 
shirsch said:
I suspect you have an ST-11M (mfm) controller rather than ST-11R (rll). Take a look at this document:

Seagate ST11M Installation Guide - Lo-tech Wiki

www.lo-tech.co.uk www.lo-tech.co.uk

If you had the 'R' version then you'd be seeing the ST-250R as a choice. Based on the drive geometry, ST-225 is now the best you can do.
Click to expand...

Thank you for the help

I'm starting to thing that yeah... got the wrong controller... :(

Do you think a more "modern" 16 bit RLL controllers without ROM like those western digital will handle a ST-250R ?

Thank you
 
vwestlife said:
What kind of computer are you using it in?
Click to expand...

At the moment I am testing it on a socket 7 - Pentium 233 MMX :)

But the idea was to put it on an XT machine (when I get an XT motherboard)

Is there a possibility to flash a new ROMs to the controller ?
The strange part is that the second ROM chip says ST-11R microcode V 1.7... so I thought there would be RLL possibility on this card..

thank you for the help

Here are some pictures... two rom chips, one saying ST-11 and the other ST-11R microcode...
 

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vwestlife said:
What kind of computer are you using it in?
Click to expand...

OMG! I was just watching a video on youtube and noticed the logo was the same as your avatar ! LOL small world

I just watched you "Rustbucket 1999 Celeron Book PC resurrected" video :)

awesome channel ! Specially the PC and computer related stuff ;)
 
I don't know about re-flashing the existing firmware, but it may be possible to program a couple of EPROMs with ST-11M code. But, do you really want to go down that path? Another possibility: There may be one (or more) 0-ohm SMD resistors or jumpers that need to be relocated. Let me dig out an ST-11M and get some decent photos for you.
 
shirsch said:
I don't know about re-flashing the existing firmware, but it may be possible to program a couple of EPROMs with ST-11M code. But, do you really want to go down that path? Another possibility: There may be one (or more) 0-ohm SMD resistors or jumpers that need to be relocated. Let me dig out an ST-11M and get some decent photos for you.
Click to expand...

You see here:

www.ebay.com

Seagate ST-11R 8-Bit ISA RLL Controller (1989) | eBay

Find many great new & used options and get the best deals for Seagate ST-11R 8-Bit ISA RLL Controller (1989) at the best online prices at eBay! Free shipping for many products!
www.ebay.com

This guy is advertising exactly the same controller as mine as an RLL ... but it seems it is not RLL at all... :(
 
Well, I'm afraid the news is not good. I could have sworn I had both flavors of the ST-11, but I have only a single ST-11R. Maybe someone else here can help?
 
Oh... Nuts. I didn't have enough coffee when I posted today. Just remembered it's the ST-11R that you actually want. The board and firmware revisions are different (older) than the one you have and mine shows a couple of EC wires in the lower right. One difference that stands out: Yours is missing an SMD resistor between the Cirrus Logic chip and the custom ASIC in the lower right. This very well may be intentional so I'd be careful about charging ahead and installing one.

ST11_front.jpgST11_rear.jpg
 
We have a definite smoking gun! I found this on a Japanese web page. It's the same board revision as yours, but that resistor is installed. If you have the skills, install an 11K ohm resistor across those pads and see if the menu options change. While it's not likely this will hurt anything, I cannot take responsibility if it does.

UPDATE: I just realized that your controller does not have a 15Mhz. crystal either. That's a fairly strong indication that it isn't able to operate at RLL data rates. Maybe the resistor mod is a red herring...

seagate_st11r_dual_rom.jpg
 
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shirsch said:
We have a definite smoking gun! I found this on a Japanese web page. It's the same board revision as yours, but that resistor is installed. If you have the skills, install an 11K ohm resistor across those pads and see if the menu options change. While it's not likely this will hurt anything, I cannot take responsibility if it does.

UPDATE: I just realized that your controller does not have a 15Mhz. crystal either. That's a fairly strong indication that it isn't able to operate at RLL data rates. Maybe the resistor mod is a red herring...

View attachment 1264175
Click to expand...


OMG ! Thank you so much for the help !

What a mess !
You are telling me that Seagate made two exactly identical controllers and only bothered switching from one to the other by installing some passive components?
That is EVIL !
Why not just install a jumper and have people have more options to choose a hard disk from.... ?

I dont know if I want to go through that rabbit hole... my soldering skills are not exactly legendary... maybe I will search for a "real" RLL controller armed with this knowledge and sell or use this one on a compatible MFM drive.
 
Chuck(G) said:
The ST11R was used on a number of hardcards. I had one with an 80MB drive, which might explain the left-side mounting holes.
Click to expand...

You are right my friend... this kind of controllers were much probably designed for hardcards .. they even have this auxiliary power supply connector
 
nunoalex said:
OMG ! Thank you so much for the help !

What a mess !
You are telling me that Seagate made two exactly identical controllers and only bothered switching from one to the other by installing some passive components?
That is EVIL !
Why not just install a jumper and have people have more options to choose a hard disk from.... ?

I dont know if I want to go through that rabbit hole... my soldering skills are not exactly legendary... maybe I will search for a "real" RLL controller armed with this knowledge and sell or use this one on a compatible MFM drive.
Click to expand...
Well, as I said in my 'UPDATE' your board also lacks the 15 MHz crystal that would be needed to deal with RLL data rates. Raw signaling rate from an MFM drive is 10 MHz, RLL is 15. I should have spotted that earlier. But, yes, I think the differences between the boards is minimal. They may both use the same ROM images.

Getting a proper RLL controller is your best bet.
 
To be fair, these controllers were originally sold paired together with a pre-formatted Seagate hard drive. So the buyer wouldn't need to know what kind of encoding method it used, as long as it worked and delivered the advertised capacity.
 
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