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Tandy 2000 hard drive questions

RichCini

RichCini

Veteran Member
Joined
Aug 7, 2005
Messages
547
Location
Long Island, NY
All:

I was *finally* able to get a CM-1 monitor for my T2k system so the only thing hanging out there to fix is the lousy HD system. It almost never boots. I've re-seated the card several times; the hard drive spins so I don't think it's a power problem. It's almost like the card never resets. I've done the usual kinds of things like re-seat chips, spray contacts, etc.

I also would like to get a second floppy drive for it without cannibalizing my other system (which suffers from similar HD problems).

Any ideas of what to look for next?

Thanks!
Rich
 
You don't say if it's an internal or external HD. Both were options.

On an internal one, I'd reformat and re-install the the operating system since component values change over time and the drive may be running a little slower or faster than when it was formatted last.

Adjusting the speed on the hard drive requires a scope, a frequency counter and specialized software. It is also a procedure that took 5 pages of instuctions.

The next thing I'd look at, especially if the HD is internal and was added later was to see if they added in the 38w power supply for the hard drive. A lot of people that added a third party HD didn't use the add-in power supply and just used the main supply eventually damaged the main supply.

As for the floppy drive, well, since they are 5.25" 720K drives, you aren't going to pick one up just anywhere, so, check Digitaldinos.com, he has some stuff available for the T2K.
 
Druid6900 said:
You don't say if it's an internal or external HD. Both were options.

On an internal one, I'd reformat and re-install the the operating system since component values change over time and the drive may be running a little slower or faster than when it was formatted last.

Adjusting the speed on the hard drive requires a scope, a frequency counter and specialized software. It is also a procedure that took 5 pages of instuctions.

The next thing I'd look at, especially if the HD is internal and was added later was to see if they added in the 38w power supply for the hard drive. A lot of people that added a third party HD didn't use the add-in power supply and just used the main supply eventually damaged the main supply.

As for the floppy drive, well, since they are 5.25" 720K drives, you aren't going to pick one up just anywhere, so, check Digitaldinos.com, he has some stuff available for the T2K.
Click to expand...

Yes, I should have indicated location, but it's the 10mb internal hard drive that was factory installed. So, it has the 38w piggy-back power supply. The controller is the model with both internal and external drive connectors.

I would absolutely reformat it if the drive actually responded. I have gotten the drive to boot before so I know it's technically bootable but doesn't boot consistently enough (or at all now). In most instances it hangs after the memory test. If I put in a bootable floppy and reset the unit, it will boot.

Now, one thing I didn't try was trying to reformat the drive using the utilities on the floppy. I do know that if I boot with the floppy and try to access the hard drive, I get the old "Drive not ready" message.

Rich
 
Druid6900 said:
Yes, IIRC, the utilities software invokes the contoller card's built in format routine, so, try that and let us know what the result is.
Click to expand...

I booted with the floppy and changed to C:

A:>C:
C:>dir

Sector not found error reading drive C:
Abort, retry, fail?

Ok, so it looks like the controller might be good enough that DOS recognized that a hard drive was connected but that maybe the drive itself is flaky (it is spinning).

Next, I ran the HFORMAT utility and it essentially bombed out, complaining that it couldn't write to the system sectors.

I have a second T2k with similar symptoms, so I can't even borrow the drive from that one to try it out. I've heard that the 20mb ST-225 MFM hard drive from Seagate has been used by some as an "upgrade" to the 10mb Tandon. Maybe I'll try to locate one of those and see if that works.

Any other ideas besides locating a new drive? I did contact Digitaldinos to see if they had a HD kit left.
 
Well, if you got a C:> prompt, it means it, at least, has some good tracks and it might be just the FAT(s) blown off.

It's been quite a while since I worked on a T2K hard drive sub-system (mine is a dual floppy) so, can you let me know what hard drive contoller they are using? I know some were propietory (or re-stamped 3rd party) and some were WD (in the earliest models) and it may be possible to force a format by going through debug right to the controller's format routine (I've worked on so many Tandy machines when I was manager of one of their repair depots back then that I might be mistaken about what their utility software does).
 
Druid6900 said:
Well, if you got a C:> prompt, it means it, at least, has some good tracks and it might be just the FAT(s) blown off.

It's been quite a while since I worked on a T2K hard drive sub-system (mine is a dual floppy) so, can you let me know what hard drive contoller they are using? I know some were propietary (or re-stamped 3rd party) and some were WD (in the earliest models) and it may be possible to force a format by going through debug right to the controller's format routine (I've worked on so many Tandy machines when I was manager of one of their repair depots back then that I might be mistaken about what their utility software does).
Click to expand...

Yeah, me to. The controller uses a WD chip but the controller has no ROM on it. It's a RS board but not like any other "standard" controllers of the day where you could just go "g c800:5" in Debug and get to the low-level format routine. There is a separate program called HFORMAT which does the formatting for the drive (instead of FORMAT). I have not been able to locate any "low-level" formatting like was provided in the ROMs on early PC add-on drives.

Issuing any commands from the "C:" prompt results in a "Bad unit error on drive C:/Abort, Retry, Ignore?"

I think at this point I'm going to need another MFM HD for testing. Unless someone has low-level formatting or diagnostics programs that can be used on the T2k.

Oh, and I could use a spare floppy drive to make mine a dual-floppy system.
 
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Druid6900 said:
Yeah, that's about the only option I can see at this point, ther than hooking the HD up to another controller in another computer and seeing if it will format.
Click to expand...

I think I have a full-length MFM card for the PC somewhere around here. Do you think that I could stick that in a 90's era PC and it'd work? I guess I should disable the internal IDE controller. It's been so long since I've worked with MFM. What kind of interleave should I use? ISTR an interleave of 5 or 6 depending on the drive speed.
 
Yes, it should work, I've used P2 motherboards to resurrect old hard drives. Make sure the controller has a BIOS and do the debug route.
If the drive doesn't format, then we know what the problem is, if it does, then we have to start looking for another cause.
 
Druid6900 said:
Yes, it should work, I've used P2 motherboards to resurrect old hard drives. Make sure the controller has a BIOS and do the debug route.
If the drive doesn't format, then we know what the problem is, if it does, then we have to start looking for another cause.
Click to expand...

I did some tinkering tonight. I haven't gone to the attic to dig out an MFM card yet but I did pull the other HD and controller from my other Tandy 2000 and swapped things around. I connected both hard drives to each controller. The external drive is connected to the external connector (straight-through pinning) on the controller and is still terminated (which I don't know is correct). There is a jumper on the drive "1-2-3-S" which I take to mean the drive select jumper. I moved it to "2".

Both C: and D: appear active because I can change to each drive, but when I try to access them, I get a "Bad unit error reading drive [drive:]" error. The drives are spinning but obviously not responding to commands. The servo counterweight is exposed on the TM502 drives and it doesn't move at all. If you try to move the counterweight by hand with the drive on, you feel the back EMF. The servo moves freely with the power off.

I did get my hands on an ST-225 drive but that'll take a week to get.
 
Strange that both sub-systems would display the same malfunction, but, I suppose anything is possible.
Ok, let's wait until the 225 arrives and see what happens then.
I used to have a dual drive system with a hard drive but someone offered me more money than I could refuse for it, but, it sure would come in handy with this problem.
 
Druid6900 said:
Strange that both sub-systems would display the same malfunction, but, I suppose anything is possible.
Ok, let's wait until the 225 arrives and see what happens then.
I used to have a dual drive system with a hard drive but someone offered me more money than I could refuse for it, but, it sure would come in handy with this problem.
Click to expand...

It is odd indeed. Several things possibly come to mind. First, the control cable upside-down. This is not likely since the connectors and cables are keyed and I hand-verified pinning.

Second, the failure mode for this system is in the head servo drive system. I'm unsure about this only because I can feel the back EMF on the head motor. So, it would have to be the drive signal to the head servo and not the motor driver itself.

The 225 is coming from Andover, MA, so I should have it by the end of the week.

Does anyone have schematics for the TM502 hard drive? I located the manual on bitsavers.org but no schematics. How about schematics or service manual for the Tandy hard disk controller? I'll have to pull out the Tech Ref manual and see if the controller schematic is in there.

I also checked my stock of controllers and I only have ESDI controllers. Off to eBay I go...
 
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Tell you what, I have lots of controller cards from the period and a known good TM502, so, you just pack up one of those suckers and ship it to me and I'll figure out what's wrong with it, fix it, tell you how to correct the problem in the other one and, possibly, send the working one back. LOL
 
Druid6900 said:
Tell you what, I have lots of controller cards from the period and a known good TM502, so, you just pack up one of those suckers and ship it to me and I'll figure out what's wrong with it, fix it, tell you how to correct the problem in the other one and, possibly, send the working one back. LOL
Click to expand...

I may take you up on that! I found an MFM card on eBay (makes sense to have one in stock anyway) and I have the two TM502s and an ST225. Let me play around with it and I may send you one of the TM502s for experimentation.

PM me your address.
 
Druid6900 said:
I meant the WHOLE T2K :)

Ok, let's see the results of the new controller/hard drive combo and go from there.
Click to expand...

I do have a spare :) It would be minus a working HD and floppy, though (I want to stick the spare floppy in mine to make a dual-drive 2000HD). As an offset, I have two VM-1s and an Atari ST1224 monitor which is supposed to work as a sub for the CM-1 with the proper connector.

I connected the ST225 to the external port on the controller and jumpered it for ID=1. Running HFORMAT worked this time, and the access light on the drive went on. It appears that both of the Tandon drives have failed, but everything else seems OK.

It also appears that at least the external port on one of the controllers is shot. HFORMAT produces a drive of 10mb. I read somewhere that there were hidden parameters for HFORMAT to enable up to 15mb or 20mb but I can't find a reference anywhere for how that's accomplished. I may try low-level formatting it on the PC and then moving it to the T2k and just doing SYS D: to make it bootable.
 
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Rich:
Did you buy the MFM controller yet for your XT/AT. I have several you're welcome to for the price of shipping. I'm located in Nothern NJ. Do you want 8-bit or 16-bit controllers.

Low level formatting with one controller may not produce a usable drive on another controller. There was lots or proprietary stuff going on in the various MFM/RLL controllers.

Did you try a hex dump of HFORMAT? You may be able to find the various options hidden in the text/data portion of the program.

Kelly

I just found this in the comp.sys.tandy group:

There are two options that might be of use on the Tandy 2000 HFORMAT program.

HFORMAT /p < will cause the program to ask for number of heads & cyls.
DO NOT go over 32 megabytes!


HFORMAT /b < prompts for the 'bad track' data


These can be used in combination with each other & the /s option. I am told
this is buried somewhere deep in the owners manual.
 
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kb2syd said:
Rich:
Did you buy the MFM controller yet for your XT/AT. I have several you're welcome to for the price of shipping. I'm located in Nothern NJ. Do you want 8-bit or 16-bit controllers.

Low level formatting with one controller may not produce a usable drive on another controller. There was lots or proprietary stuff going on in the various MFM/RLL controllers.

Did you try a hex dump of HFORMAT? You may be able to find the various options hidden in the text/data portion of the program.

Kelly

I just found this in the comp.sys.tandy group:

There are two options that might be of use on the Tandy 2000 HFORMAT program.

HFORMAT /p < will cause the program to ask for number of heads & cyls.
DO NOT go over 32 megabytes!


HFORMAT /b < prompts for the 'bad track' data


These can be used in combination with each other & the /s option. I am told
this is buried somewhere deep in the owners manual.
Click to expand...

Kelly:

Thanks for this info! I just tried the following "HFORMAT d: /s /p" and it worked. It prompted for interleave, heads and cylinders. It formatted it and transferred the system with no problem. Now I have to remove the old Tandon drive and reassemble the whole thing. Then I can start reinstalling the software that I got with it (Lotus 1-2-3, Wordpro, pfs:file, etc.)
 
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I still find it hard to believe that both drives failed at the same time in the same way.

I'd suggest sticking the new controller and the TM-502s in another type of machine, one at a time, as drive C: and trying to format them, just to see. I can give you all the jumpers on the drive for use in a non-T2K environment.
 
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