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MFM controller cable

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bettablue

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Feb 21, 2011
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In rebuilding the IBM 5161 expansion unit, I ran into an issue where the wider MFM cable that can connect to 2 drives was too short. I was sondering if there is such a thing as a longer MFM cable, or an extension that I can add onto the one end with the twist for adding in the 2nd MFM drive side by side. (Sorry, I don't know any better way to explain it). When installing the 2nd drive, I had to be very creative in how I ran the cable over to the end of the controller. In the end, I had to run all of the MFM cables from the 2nd drive completely underneath the first drive. The smaller of the cables was OK, it was only the larger cable that gave me any real trouble.

So, is there a cable that can handle both a longer space between the controller and the first drive, AND a longer space between the 1st and 2nd drive? Or is ther an extension I can use between the 2 drives to gain the extra length I need?

Also, I'm still looking for another MFM hard disk to complete outfitting the expansion unit. Please PM me if you have a drive.

Thanks much.
 
I remember years ago having a similar issue with a different system (trs-80 coco external drives). I ended up just pulling off the ends carefully, and buying a spool of ribbon cable at radio shack. Problem is I don't think radio shack sells ribbon cable anymore. :S I still have some, if you can't locate any. At least 30-40 feet.

You will most likely have to make your own cable. Also I have a drive if your interested, st-225, but its missing the bezel. Not sure its working condition, been sitting on a shelf for years... It was parked w/ sit.com before being pulled though. :thumbsup:
 
I was about to say "just fit a single ST225", but if I had 5161 I'd want that badboy loaded out too!

ST-225's are good drives.
For 20Mb drives tho you'd want to check your controller has Type 2 hard drive support, and for any early drive be sure it was parked before being sent.

Another cheeky resource for connectors and cable is old floppy cables - you just need to remove the A-drive-twist and make a new C-drive-twist like the current cable has (or be lazy and set C drive to DS0 instead of DS1, which is what I do). If only I could find the same for 20 pin data connectors :(
 
Thanks for the quick responses. I am in the works to possibly buy a drive and controller combo at a very good price. Someone sent me a PM telling me what they have, so I'm looking at going that rout.

As far as the cable is concerned. It almost sounds like it's a very simple thing to do to remanufacture these cables. Spider, and TwoLazy; I don't know what you mean by "be lazy and set C drive to Ds0 etc. However, if I send you an extra cable I have, do you think you could put together a cable for me? I kind of think I understand what you mean, but I do want to make sure everything is set up properly in the 5161 expansion unit. If all it takes is to remove the connnectors and reattach them after making the "twist", I'm sure I could do that. In theory, I guess you could make a drive ribbon and any desired length, am I correct?

I just had a small problem though. My wife did some housekeeping and she tossed out an entire box of ribbon cables. I can probably make the ones I have work OK, but If there was some way I could just purchase a cable with the length between drives extended by about 4" and the length from the contoller to the first drive also extendsed by 4 ". That would give me a total of 8 inches of expansion on that cable and with that I could run it pretty much anywhere I needed. Let me know if this is something we can set up.

Thanks again.
 
SpidersWeb said:
Another cheeky resource for connectors and cable is old floppy cables - you just need to remove the A-drive-twist and make a new C-drive-twist like the current cable has (or be lazy and set C drive to DS0 instead of DS1, which is what I do). If only I could find the same for 20 pin data connectors :(
Click to expand...
Not quite... that configuration will only work with a ribbon cable with no twist at all. So, he'll still need to tear the ribbon apart to remove the (floppy) twist.
 
BB, I have something very unusual that would no doubt solve your problem with very little effort. This is something I picked up a long time ago when I was running external floppies and hard drives from my 286. Not external floppies and HDs, mind you, but normal, internal drives attached to another power supply, outside the box.

I obviously needed longer than normal cables to get these drives to my controller(s) located inside the box so here's what I did. I picked up a couple of double-sided PCB edge card connectors. This allowed me to connect two ribbon cables together to extend them. It worked like a charm and I used that setup for many years with no problems.

If you're interested I'll dig this little device out of wherever it's hiding. :smile:

Here's a pic... P4200140.jpg
​
 
bettablue said:
I can probably make the ones I have work OK, but If there was some way I could just purchase a cable with the length between drives extended by about 4" and the length from the contoller to the first drive also extendsed by 4 ". That would give me a total of 8 inches of expansion on that cable and with that I could run it pretty much anywhere I needed. Let me know if this is something we can set up.
Click to expand...
Here's another option. How long is the cable you have from the controller to the first drive connector and how long is it between the two drive connectors? I have some NOS 36" floppy ribbon cables and I could convert one to match your needs -- once you confirm the current measurements you're working with.
 
I have saved every cable over the years and have a LOT, including 16-pin, 20-pin, 34-pin, 40-pin, 50 pin, ribbon cables, Centronics, DB-9, DB-25 and some others. Everybody should become expert at removing connectors and reinstalling them as needed.
 
Stone: I'll take you up on that. Just for S&G, do you happen to have an edge connector for the smaller MFM cable too? If possible, I want to lengthen both cables so there is no stress anywhere in the cabling or on the controller card or drives. Hmm. Did the expansion unit come with a special, longer cable set? Just let me know what I owe you for the cable you're making and the edge connector for the smaller cable if you have one. I'll send payment through Paypal.

I also have someone else putting together a cable for me too. But I want to keep both options available. Besides, if a cable is too long, I can work with that. When a cable is too short that causes problems.

The primary cable that needs to be lengthened is the larger of the two. So, IF you can add about 4 inches to each section, one to allow more room to rout to the first drive, then the other section to allow connecg the same cable to the 2nd hard drive. We're talking about 8 inches total, if possible.

Thanks again.

Stone said:
Here's another option. How long is the cable you have from the controller to the first drive connector and how long is it between the two drive connectors? I have some NOS 36" floppy ribbon cables and I could convert one to match your needs -- once you confirm the current measurements you're working with.
Click to expand...
 
barryp said:
I have saved every cable over the years and have a LOT, including 16-pin, 20-pin, 34-pin, 40-pin, 50 pin, ribbon cables, Centronics, DB-9, DB-25 and some others. Everybody should become expert at removing connectors and reinstalling them as needed.
Click to expand...

I agree. That's why I'm going to look for an old ribbon cable I can play around with. As I see it, that is something I can learn. The bad part for me is that I am a polio survivor and only have one arm that works. So manipulating smaller things like that is much more difficult for me. I appreciate the assistance of those two gentlemen immensly.
 
I keep a few spools of ribbon cable around--that way, I can make any length of cable that suits me, including some 6 and 8 foot cables for tape drives. Having 50 and 34 conductor bulk ribbon is a good way to go--with some searching, sometimes you can find it as surplus. I prefer Spectra-strip type--I don't have to count conductors when I'm looking to single out one.
 
bettablue said:
The primary cable that needs to be lengthened is the larger of the two. So, IF you can add about 4 inches to each section, one to allow more room to rout to the first drive, then the other section to allow connecg the same cable to the 2nd hard drive. We're talking about 8 inches total, if possible.
Click to expand...
Yes, but the reason I asked for your exact measurements before is that floppy/hard ribbons come in many sizes and simce I'm not there I don't want to send you something that might not fit. So, take the measurements and then I can be sure of what I'm doing. :) You can either give me the two measurements I asked for above or the total length and the length between the two drive connectors, either way. Just make sure you specify what measurements you're giving me. You don't even need to be too precise. The nearest half inch will suffice.
 
Hard disk Compatability question

Hard disk Compatability question

In addition to the cable issues we have been discussing in this thread, I have an opportunity to purchase a Control Data 20mb Full-height + Paired controller from a member who replied to this thread. The price is perfect for me, but is this combination compatible with my miniscribe 2012 11 Meg hard drive? Or is the Xebec controller compatible with the Control Data 20 Meg drive? I'm including information on the Xebec controller that Chuck supplied in another of my threads.

From Chuck (G)

"very close to "Variation #2". It's assy. 104836-Rev C-04-06. It has the option jumpers installed (4 of them) and a 28-pin socket for a 2764 BIOS ROM. Currently, there's an SMS/OMTI 5520 ROM installed (giving 16 drive types)"

If either combination will work, I'm going to purchase the drive and controller.

Thanks again everyone.
 
Gotcha. The reason I gave you the measurements I did was because the system is currently assembled. However, from what I can tell, the connection from the controller to the first drive is 9 1/2 inches, and the distance between the two drive connectors is 10 inches, but there will need to be additional room for the cable to be routed and bent into place. Because of the way ribbon cables have to be kind of folded into place to change direction, adding let's say, another 2 to 2.5 inches between the drives will be fantastic. That way I can run the ribbon under the drives and up to their connectors.

Since you're doing that. I'll tell the other guy to hold off.

Thanks again stone.

Stone said:
Yes, but the reason I asked for your exact measurements before is that floppy/hard ribbons come in many sizes and simce I'm not there I don't want to send you something that might not fit. So, take the measurements and then I can be sure of what I'm doing. :) You can either give me the two measurements I asked for above or the total length and the length between the two drive connectors, either way. Just make sure you specify what measurements you're giving me. You don't even need to be too precise. The nearest half inch will suffice.
Click to expand...
 
I'll make it roughly 20" - 21" from controller to the first drive and 15" - 16" between the two drives.

That brings up one more question. You're going to use this on the Xebec controller, right? IIRC, that has a 34 pin header to connect to the ribbon cable, right? Not some 34 connector card edge like on the old floppy controllers, right? Just wanna be sure. :smile:

BTW, I don't have that data cable (20 connector) double card edge adapter you asked about but I do have some longer data cables. How long is yours and how long does it need to be?
 
Hi
A 90 degree bend add the width of the cable
to the length.
Run a string from connector to bend to
connector.
That should get it right
Dwight
 
bettablue said:
In addition to the cable issues we have been discussing in this thread, I have an opportunity to purchase a Control Data 20mb Full-height + Paired controller from a member who replied to this thread. The price is perfect for me, but is this combination compatible with my miniscribe 2012 11 Meg hard drive? Or is the Xebec controller compatible with the Control Data 20 Meg drive?
Click to expand...
Take a look at the following link to gain an understanding of how to answer those two questions.
http://www.minuszerodegrees.net/5160/hdd/hdd_question.htm
The link is not comprehensive (e.g. doesn't cover autoconfigure controllers) - its aim is to provide a basic understanding, which should be enough for you to answer the questions.

The Xebec controller Chuck supplied has a "SMS/OMTI 5520 ROM". That ROM will define the drive types. Maybe Chuck can tell you what those types are. Otherwise, SpeedStor software may be able to list the types via its /romlist option (done via A:\>sstor /romlist)
 
After I learned that Thomas was getting a Miniscribe, I re-installed the original Xebec ROM.

I believe it has the following 4 selections for each drive:

306/4/17 off-off
612/4/17 off-on
615/4/17 on-off
306/8/17 on-on

At any rate, it's one of the IBM ROMs, so I think that's the one I put in.

You can check by using debug to look at C800:0. You should see:

Code: 
55 AA 08 EB 35 35 39 58-37 32 39 31 20 28 43 29   U...559X7291 (C)
20 43 4F 50 59 52 49 47-48 54 20 49 42 4D 20 20    COPYRIGHT IBM
43 4F 52 50 2E 2C 31 39-38 32 20 2C 31 39 38 35   CORP.,1982 ,1985
2E 20 31 30 2F 32 38 2F-38 35 2B C0 8E D8 FA A1   . 10/28/85+.....

If you don't see that, let me know what you do see and I'll look it up. Too many ROMs, too little time.
 
OK, so what am I doing wrong? When I run the Debug command the computer accepts that, but it doesn't accept the address you provided. I tried C800:0 C80:00.0. and multiple other variations, all come up with the same ^error

I would like to try doing this without taking the system down just now. It took me forever to get it set up the last time and my best friend won't be here for another week.

Chuck(G) said:
After I learned that Thomas was getting a Miniscribe, I re-installed the original Xebec ROM.

I believe it has the following 4 selections for each drive:

306/4/17 off-off
612/4/17 off-on
615/4/17 on-off
306/8/17 on-on

At any rate, it's one of the IBM ROMs, so I think that's the one I put in.

You can check by using debug to look at C800:0. You should see:

Code: 
55 AA 08 EB 35 35 39 58-37 32 39 31 20 28 43 29   U...559X7291 (C)
20 43 4F 50 59 52 49 47-48 54 20 49 42 4D 20 20    COPYRIGHT IBM
43 4F 52 50 2E 2C 31 39-38 32 20 2C 31 39 38 35   CORP.,1982 ,1985
2E 20 31 30 2F 32 38 2F-38 35 2B C0 8E D8 FA A1   . 10/28/85+.....

If you don't see that, let me know what you do see and I'll look it up. Too many ROMs, too little time.
Click to expand...
 
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