Texas DS990/1 Dump

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pieroandreini
Posts: 32
Joined: Mon Apr 27, 2015 8:45 pm

Texas DS990/1 Dump

Post by pieroandreini »

Hello,

I'm trying to make copies of several 8 "floppy disks that contain the Texas Instruments DS990 Model 1 operating system. They are very rare floppies, this system is almost impossible to find and I want to be sure to make right dumps.
I connected the original disk drive to kryoflux by Dbit FDADAP as recommended in other posts.
I dumped a couple of disk in "preservation mode" but I wanted to know if it was better to set some known parameters and if I can write the dumps back on other floppies to try to boot from the copies.
Attachments
fd1000_format.jpeg

SomeGuy
Posts: 272
Joined: Wed Feb 18, 2015 8:18 pm

Re: Texas DS990/1 Dump

Post by SomeGuy »

The specs you posted seem to suggest standard FM/MFM soft sectored encoding. So, if your originals were in very good condition, you could probably could just write the preservation stream back to a new disk.

Note that preservation streams also preserve any "noise" present on a disk. I've found that marginally damaged disks may decode OK with Kryoflux/HxC/PCE tools, but just writing the stream back to a new disk will write the "noise" and may result in a disk that is not readable at the same area where there was damage.

Basically, try it and see what happens.

It may be desirable to first reduce the preservation stream to a "lowest common denominator" format, in this case probably an ImageDisk format and then create a fresh noise-free stream file. HxC is really good with this - just open the Stream file, if it shows no decoding errors, save to ImageDisk, load the ImageDisk file, then save to a Kryoflux Steam format. (Note that the HxC software tool is a third party tool and is not made by or supported by the Kryoflux folks)

If in doubt, post a sample stream file and let the folks here pick over it to see if there is anything that could cause issues.

pieroandreini
Posts: 32
Joined: Mon Apr 27, 2015 8:45 pm

Re: Texas DS990/1 Dump

Post by pieroandreini »

Thanks for the quick response. The strange thing is that I can't read them with Imagedisk or Teledisk, and it has never happened to me before, except for the case in which I had to read discs written with MMFM modulation.

here some dump I made. II was unable to convert them to any format that allows me to understand if there is readable data inside

https://www.dropbox.com/s/jt212lld1wmj6gp/xxx.zip?dl=0
https://www.dropbox.com/s/79rbt2lrq6bjsgx/mill.zip?dl=0
https://www.dropbox.com/s/ob6mu9k76x7d6 ... d.zip?dl=0

ZrX
Posts: 618
Joined: Tue Dec 06, 2011 9:09 pm

Re: Texas DS990/1 Dump

Post by ZrX »

The scatter plot of those dumps shows really bad noise. So bad that they're practically unreadable. Not sure if there's something wrong with the disks or if the drive heads are dirty.

Also, manually decoding a sector from the mill-dump shows the format is non-standard such that DTC simply can't decode it.

It's MFM, uses only single 4489 syncword, 0x0A ID for sectorheader and 0x0B ID for data. Sectorsize is weird 288 bytes. 26 sectors per track. Checksums are standard tho.

pieroandreini
Posts: 32
Joined: Mon Apr 27, 2015 8:45 pm

Re: Texas DS990/1 Dump

Post by pieroandreini »

Ok thanks a lot, which setting suggest to me to try reading again?
I'm scared to damage those floppies, may I pay someone professional like you to try to read them?

brightcaster
Posts: 292
Joined: Fri Nov 08, 2013 10:48 pm

Re: Texas DS990/1 Dump

Post by brightcaster »

There is also a problem with the drives speed which has much flutter! I guess the drive needs a proper service including a change of the belt...

David

SomeGuy
Posts: 272
Joined: Wed Feb 18, 2015 8:18 pm

Re: Texas DS990/1 Dump

Post by SomeGuy »

No "setting" is going to correct this issue. The drive is outputting lots of noise to the kryoflux. Dirty heads are one possibility. To me it almost looks like some kind of head alignment issue.

It might help to tell us a little more about the drive(s) you are using. Is the drive you are reading from a drive from the machine in question? What model of drive is it/are they?

Roughly where about are you located? There could be someone in your area that might be set up for that. (Assuming that there is nothing else wildly non-standard about the drives that wrote these disks).

pieroandreini
Posts: 32
Joined: Mon Apr 27, 2015 8:45 pm

Re: Texas DS990/1 Dump

Post by pieroandreini »

I just bought a NOS floppy drive NEC FD1165, it will arrive on next days. I made the two reading with the original unit which use QUME DT/8. I live in Tuscany (Italy) in the middle from Perugia to Siena. I'm really scared to damage those floppies, the may be the last one existing... I tried to read them again with another computer after cleaning the heads. I hope that taking the best parts from both could be possible to obtain something good. May be possible to have an app that can decode .img from raw data?
Attachments
FD1000.jpg

ZrX
Posts: 618
Joined: Tue Dec 06, 2011 9:09 pm

Re: Texas DS990/1 Dump

Post by ZrX »

I have one of those NEC FD1165 drives myself. Requires just +5V and +24V to work. Interestingly they use the spindle with optical sensor to set the RPM, and mine spun at 720 RPM. Ended up buying another drive and while it was on its way I realised the sensor on the first one was just dirty. The second drive tho had seen some water damage and getting the heads clean from rust took quite a bit of effort.

For these disks I'd use maybe 50/50 mix of water with isopropyl alcohol and microfiber cloth to clean the surface, which will make reading the disks more safe if the surface is flaky. Tho spinning the 8" is kind of difficult while wiping along the surface unless the sleeve is cut open (I use a 3D printed holder to spin the platter).

The aim would be to get more or less three clearly separated lines in the scatter plot. If the drive is not making a very distict squeaky sounds while reading a disk and the surface doesn't look "groovy" like an old record the heads are likely clean and the problem is somewhere else. Else any further attempts to read without cleaning the heads and the disks should not be attempted.

pieroandreini
Posts: 32
Joined: Mon Apr 27, 2015 8:45 pm

Re: Texas DS990/1 Dump

Post by pieroandreini »

I think I made a good dump, so I moved the post here:

viewtopic.php?f=7&t=1693

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