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ralphb

Attaching external drive

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I'm trying to add my Lotharek as DSK2 and DSK3 to my PEB with a single Tandon drive. For this I'm using a standard PC floppy cable with TWO floppy connectors, one of which is twisted.


When I connect the Tandon drive only, I can catalog DSK1 just fine. When I connect the Lotharek only, I can catalog DSK2 and DSK3 just fine. (Note that jumpering the Lotharek appropriately will take care of the twisted cable, I think.) If I connect both, though, then cataloging either DSKx yields "DISK NOT INITIALIZED".


I've also tried removing the resistor pack on the drive (I suppose this is "A" in the photo, not "B"?!), but it didn't affect the result at all. (Or are you supposed to plug in something else instead?)


post-35214-0-92586600-1448396960_thumb.jpg


Is my approach misguided? What's the difference between attaching a single cable with two connectors to the main controller plug and attaching two cables with a single connector to both main and rear-facing controller plugs?


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I'm trying to add my Lotharek as DSK2 and DSK3 to my PEB with a single Tandon drive. For this I'm using a standard PC floppy cable with TWO floppy connectors, one of which is twisted.
When I connect the Tandon drive only, I can catalog DSK1 just fine. When I connect the Lotharek only, I can catalog DSK2 and DSK3 just fine. (Note that jumpering the Lotharek appropriately will take care of the twisted cable, I think.) If I connect both, though, then cataloging either DSKx yields "DISK NOT INITIALIZED".
I've also tried removing the resistor pack on the drive (I suppose this is "A" in the photo, not "B"?!), but it didn't affect the result at all. (Or are you supposed to plug in something else instead?)
Is my approach misguided? What's the difference between attaching a single cable with two connectors to the main controller plug and attaching two cables with a single connector to both main and rear-facing controller plugs?

 

It was my understanding that the resistor pack was supposed to go on the last drive in the setup, don't know if you can do that with the Lotharek and Gotek though, haven't gotten my Gotek, TI functional yet, too many irons in the fire at the moment.

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Hi,

 

just UN-twist the cable, and make the DSKx-settings with the referring jumpers or DIP-switches on the devices

No twisted floppy-cables in the TI-environment please.

 

The resitorpack must be applied to the last drive on the internal cable (your Tandon)

 

The drive on the external connector "should" be configured as DSK2, IIRC.

To be sure, set your internal Tandon to DSK1 and the external Lotharek to DSK2 (only) first.

This should run, and if so, then you can start fiddling with 2 DSK-numbers for the Lothare-Drive :)

 

If you have ie the CorpComp CC-9900 FDC, feel free to jumper the headstep for the Lotharek´s DSKx to 3 ms (this is faaaaster) :)

 

 

"What's the difference between attaching a single cable with two connectors to the main controller plug

and attaching two cables with a single connector to both main and rear-facing controller plugs?"

 

The first variant here is a config with internal drives, the second is a config with internal AND external drive.

The number of connectors on the internal cable makes no real difference here (though, more drives could be connected internally,

and dismounting the resistor-pack from the drive next to the controller/middle of the internal cable should be obeyed, of course :) )

 

 

 

Search-tags: TI-99/4A TI99 Texas Instruments

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The reason that the floppy cable, with lines 10-16 flipped for the end connector, will not work is that the motor-on and drive-select lines are defined differently for the TI and PC floppy controllers:

 

post-29677-0-63016200-1448470253_thumb.gif

 

The PC controller only works with two drives and, with lines 10 – 16 mirrored, flipping them routes the motor-on and drve-select lines for drive A (drive 0) to the pins for drive B (drive 1). All drives were jumpered/strapped to drive B (drive 1) from the manufacturer. The flip allowed the end drive to be properly selected as drive A (drive 0), even though the drive itself is set to drive B (drive 1).

 

Obviously, this does not work with the TI controllers because there is only one motor-on line, but four drive-select lines. Using a flipped cable totally botches the connection.

 

...lee

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the resistor pack needs to go on the last drive in the chain and you will need to untwist the cable. You may need to modify your selector on your floppy (chip B) to get it to the right DSK number. If that is the stock one then it's setup for DSK1.

 

You can easily switch it out with a dip switch that will plug into the socket so it's easily changed.

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Thanks to all for their replies, in particular to Lee; I always wondered what the twist actually does! So many wires, so little data ... :)

 

But as far as the drive problems are concerned, this case is not as clear as it might seem.

 

First of all, my wording was inaccurate -- I'm not attaching an external drive, I'm adding an additional internal drive (thanks to Ralf for pointing this out). BUT: The second drive is a Lotharek, which does supported twisted cables simply by jumpering the drive "backwards".

 

post-35214-0-89524200-1448560824_thumb.png

 

In fact, if I disconnect the main Tandon drive, the Lotharek, setup as DSK2 and DSK3, works just fine, despite the twisted cable:

 

post-35214-0-80251100-1448560049_thumb.jpg

 

Similarly, the Tandon, connected to the untwisted part of the cable and with the resistor pack installed, works fine if I disconnect the Lotharek.

 

Only if I put everything together I won't get any data on the TI. You can see from the photo that I removed the resistor pack from the Tandon, and that the "motor" turns on on all drives (that's the middle LED on the Lotharek).

 

post-35214-0-84099000-1448560198_thumb.jpg

 

But attempting to catalog either DSKx in DM2 will stall for a few seconds, then "DISK NOT INITIALIZED" is displayed. Same result if I re-install the resistor pack (although that should be wrong anyway).

 

Strictly speaking I should terminate the Lotharek, but there's no place to do this on the drive, so I doubt that the design requires it. Another observation: If I disconnect the Lotharek, but don't terminate the Tandon, then cataloging yields "ERROR 16" immediately.

 

So, twisted or not, I'm stymied on this one ... :???:

 

(In the meantime I'll see if I can get hold of an external cable to try to attach the Lotharek to the external controller interface ...)

 

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Or you could just untwist the cable, connect the Lotharek as Drives 2 and 3, and connect the Tandon as drive 1. The twist is the problem, as the signals are interpreted differently by the two connected drives. Kill the twist and your problem will go away (and the Lotharek may already have internal termination, which is why you don't see an option to set it).

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Exactly. NO twisted floppycables, as mentioned before. You have a twisted cable here in the picture. This will not run.

What the Lotharek is able to do does not matter for the TI-Controller.

 

So just connect the Lotharek at the middle of the internal cable, and the Tandon - with the resistorpack set - at the end of this cable.

In a first try jumper DSK1 for the Tandon and DSK3 for the Lotharek. This should work, check it, and then you can jumper

the Lotharek as DSK1 and the Tandon as DSK3 (no changes to the cables!). All as mentioned in my first post.

 

The only change now is to jumper the second drive to DSK3 instead of DSK2.

Let DSK2 free maybe for a later external drive.

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Well, let's the rest the twisted cable for a moment. :)

 

I found another floppy cable in the basement that fits the external controller plug, so I now connected the Tandon to the internal connector, and the Lotharek to the external connector (jumpers reset to non-twisted). Tandon is DSK1, Lotharek is DSK2. No twist anywhere.

 

post-35214-0-99066800-1448565632_thumb.jpg

 

And yet, the result is the same: DISK NOT INITIALIZED, motor LED works. (If I twist the Lotharek connector by 180 degrees so that it is wrong I get ERROR 16 instead.)

 

So I have no twist but this external setup won't run either, no matter if I install the resistor pack on the Tandon or not. :?

 

That's the best I can do right now, as I don't have floppy cables that are untwisted for both connectors and have exactly one "slit plug".

 

EDIT: Now that I look at the PHP1250 manual ... Page 13 depicts a "special cable" for connecting external drives, and yes, the cable I have (but that I did not use here) is a weird contraption involving twists (?) and a small adapter board, just like in the manual picture. Would a standard untwisted PC floppy cable even work for external drives?

 

EDIT 2: How can I jumper the Tandon to be DSK2? Would I have to move the "shunt pack" (B)? The manual doesn't tell.

Edited by ralphb

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The resistor at the Tandon MUST be set, as it is at the outer end of the internal cable

 

Is it set ? (I cannot recko on the pic, and don´t know this drive)

 

Maybe try as I mentioned before, and not external.

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Maybe the Tandon´s resistor-pack is damaged ? Maybe an issue with the controller ?

you could leave the resistor off from the Tandon, for a test, normally this "works"

 

Jumpering the old drive is like the old TI-drive (90/180KB):

You have to break or close(solder) these "weird" contacts.

 

 

This should be the DSKx-referring shunt-pack, means "jumpers-pack"

 

post-41141-0-76202900-1448567117_thumb.jpg

 

 

 

 

 

Classic shunt-pack, pre-jumper-technic:

 

/EDIT/ ...and as Ksarul mentioned (later :) ) please find the Resistor-Pack here next to the left from the shunt-pack

 

post-41141-0-68607900-1448567512_thumb.jpg

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Jumpering the old drive is like the old TI-drive (90/180KB):

You have to break or close(solder) these "weird" contacts.

 

Yep, but I don't know what the pins mean ... I've looked at an external drive, which I suppose is configured to be DSK2 or DSK3, and this has a bunch of open contacts, but the entire jumper pack is one pin less than the one in my Tandon, so I cannot even swap them as-is. :roll:

 

Which pins do I need to open for DSK2?

 

EDIT: That's what my external drive looks like, but the Tandon has one additional pin ... I guess I could try all 2^8 possibilities. :)

Edited by ralphb

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You can run the Tandon alone, and just try with the diskmanager on which DSK it works/runs. Then watch the shunts.

Also would be nice to know the drives manufacturer-number. Should be printed on it. To have a looo for the manual.

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..but normally shunt-pack and jumper-bank are indentically, DS0, DS1, DS2......

BUT the jumper/shunt on position "DS0" sometimes means "DS1" !! so you have to try it.

(As mentioned before, set a jumper/shunt-config, and check the drives reaction with the diskmanager)

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Here an example for a Tandon-drive, but I need the correct number:

**********************************************************************                      J   U   M   P   E   R   S**********************************************************************TANDON   TM252  USER'S MANUAL P/N 179050-001B, 1984 Jumper Setting ============== Drive Address and Option Selection ---------------------------------- The drive address and option selection is determined by the programmable jumper blocks located on the logic circuit board. If jumper configurations are changed, power shoulf be cycled off and on, so that the microprocessor can recognize the new configuration. +------+----------------+------------+-----------------------------+ |Option|Function        |Factory     | Usage                       | |Jumper|                |Programmed, |                             | |      |                |User Access.|                             | +------+----------------+------------+-----------------------------+ |W15   |Drive Select    |      I     |Omit W15 for drive-to-       | |      |                |            |controller lines, enabled    | |      |                |            |when drive not selected      | +------+----------------+------------+-----------------------------+ |W16   |Index           |      I     |Omit W16 for index-to-       | |      |                |            |controller line, enabled when| |      |                |            |drive not selected.          | +------+----------------+------------+-----------------------------+ |RTW7  |Read Terminator |      I     |Install only at the end drive| |WTW8  |Write Terminator|      I     |for daisy chain data. Install| |      |                |            |in all drives for radial data| +------+----------------+------------+-----------------------------+ |S4W9  |Drive Select 4  |      O     |Install one of four plugs    | |S3W10 |Drive Select 3  |      O     |only. Plug corresponds to    | |S2W11 |Drive Select 2  |      O     |drive address.               | |S1W12 |Drive Select 1  |      I     |                             | +------+----------------+------------+-----------------------------+ |U19   |Terminator Pack |      I     |Install at the end drive only| |      |                |            |for daisy chain control lines| +------+----------------+------------+-----------------------------+ O = Omit I = Install
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I had a final go at it. First I noticed that the first floppy cable actually has TWO untwisted connectors, just very close together. :dunce:

So I hooked up Tandon and Lotharek to the internal connector using two untwisted connections, installed the terminator in the Tandon, configured the Lotharek as DSK1 and the Tandon as DSK2, unplugged the power from the Lotharek, and verified that the Tandon was working as DSK2. Then I powered on the Lotharek, and -- back to square one, DISK NOT INITIALIZED. I even tried a different controller card, but same error.

 

So I'm out of ideas for today ... People, if we don't get this going I swear I'll bring it to Birkenau next year! :lolblue:

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Here an example for a Tandon-drive, but I need the correct number

 

Oh, this is more sophisticated than I thought. Maybe you're on to something ... In any case, my model is a TM100-2A. Didn't think to look for the Tandon manual instead of the PHP1250 one!

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I'm off to eat right now, but I'll add a whole lot to the shunt pack and terminating resistor discussion when I get back, as this information keeps disappearing from the user base. . .

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...and maybe we can see the problem here ha ha :)

 

EDIT: No, this just seems to be the "controller-side" of the drive or so ) :)

 

 

(from the 1983er manual)

 

post-41141-0-95317200-1448570505_thumb.jpg

Edited by schmitzi

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this seems to be the needed schematic.

Looks familiar to other drives:

 

I think if you set/short the first shunt "DS0" here, that you get DSK1 on the TI-controller.

But you have to check that (DiskMan)

 

post-41141-0-59505900-1448570689_thumb.jpg

Edited by schmitzi

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Good find on that last diagram, Schmitzi, as that was one of the things I was referring to. You can replace the weird chip frame with the contacts with a set of DIP switches. Then just make sure you set the same control lines ON as the metal shunts had (and put the rest to OFF, with the exception of the DS Line you plan to use). Most drive manufacturers numbered them from "0" to "3", with "0" being drive "1" for the TI. If they used the DS starting at "1" (as opposed to "0"), then that is drive "1" on the TI too.

 

Lastly, there is that resistor shunt pack thing. Note that it is a separate object--and for your TI, each chain of devices needs to have the LAST device in the chain with an installed resistive shunt pack. If you have devices on the internal connector AND on the external connector, the last one on each connector needs the shunt.

 

The chip titled 314B151 is the resistive shunt in Schmitzi's picture above. The part number breaks down as follows:

 

3 = .300 inch wide package

14 = 14-pin package

B = I don't remember off the top of my head

151 = 151 Ohms

 

The rating can be as much as 330 Ohms and as low as 151. We used everything in that range BITD.

Edited by Ksarul
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