New Nabu 1600

Topics for the NABU 1600 computer exploration and development
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snuci
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New Nabu 1600

Post by snuci »

I got my Nabu 1600 today. First issue was a bad power supply. It would work for a few seconds and then shut down. +12v and -1v were fine but 5 volts was never achieves. There is a small round transformer that had a chip out of it so I'm not sure if that failed at some point and is causing the issue. I replaced it with a Meanwell I had on hand and all is well.

Second issue I am having is communication with the Nabu 1600. I can talk to it but it slows down the output and stops talking. I'm not sure if the 1600 is freezing up or if it's just serial communication. I think the one of the ways I can tell is if I create the floppy cable and see if it proceeds to try to boot from floppy. I have gotten to the "Insert floppy" message but I don't get there too often so I'll have to do some troubleshooting.

Anyway, that's it for now. At least it's booting... to a point :)

Santo
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DJ Sures
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Re: New Nabu 1600

Post by DJ Sures »

Hey awesome to see another 1600. I’m excited to see what you end up doing with it. I have been away from nabu for the summer. A little discouraged from the way last season went with the politics - not sure if I’m excited to jump back in. But I have a hundred ideas that will continue to push the limits of nabu. So who knows what the future holds yet :). In the meantime I have some feedback on the serial communication with the 1600 that I experienced. In one of my videos I had a bunch of troubles with a windows based serial terminal. I ended up switching to a dos based (Kermit or telix I forget). You may want to try a different terminal to remove that as a cause.

My plan with the 1600 was to use an arm micro to emulate the wd protocol. Reviewing the data sheet it’s not too difficult because it’s well documented.

As for the floppy - there’s on onboard controller so we just need to find if gotek or something will support it. If that’s the case we can get cpm or dos running easily. Although it’ll be terminal based dos, so no duke nukem!
snuci
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Re: New Nabu 1600

Post by snuci »

Well, I got a little further but not too far. After spending lots of time on it and the 1600 hanging when I started to communicate with it, I found a bad 74ALS645 at U42. I have just ordered a replacement. I made the proper DTE to DCE pigtail adapter and that didn't help, obviously, but that was before I found the issue.

I did make the floppy cable and at one point I got a floppy error. On a rare occasion if I got that far, it would load forever, stepping tracks once in a while but then it would die and not finish. I suspect the issue I am having won't let me get further.

I also have a real WD1001 so there's some possibilities of trying to re-create Leo's storage set up. That's a whole other kettle of fish and I'm not even thinking that far quite yet. Baby steps for now.

DJ, as for the other crap, do it for yourself and don't worry about the BS. It's much more satisfying that way :)
Nabu 1600 set up with floppy drive
Nabu 1600 set up with floppy drive
Boot attempt but dies after disk access
Boot attempt but dies after disk access
Let's see what happens when the part arrives in a couple days.
Santo
snuci
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Re: New Nabu 1600

Post by snuci »

I replaced the component but that did not fix my communication issues. What I was seeing was a initial boot okay but as I rebooted, it would get less and less through the initial POST until, for whatever reason, I had to turn everything off, wait a while and then try again.

As it turns out, I was missing all of the jumpers on J8 and J9. The schematics has these marked down. I put them in as noted for asynchronous communication.

I was also missing at T18 as noted in the schematics. Without it, the computer was in diagnostic mode. With it now in, it's in normal mode. Not sure what the difference is but it's probably best in normal mode.

I was using Dave Dunfield's QNX and CP/M 86 images. CP/M 86 gives me a disk error (I am running on a Gotek and the image was converted to HFE format as it was captured). QNX just goes to track 74 and slowly goes from one side to the other, then to the next track, then other side, and so on. It never boots.

Here's the kicker. My Nabu 1600 is earlier and it has the WD1793 floppy controller chip in it. The later ones (Dave Dunfield's for example) has a 2793 which adds circuitry for write precompensation. What this means is that I am not sure my 1600 can read those diskettes without modification to add the WD2793 chip like Dave's who provided the disk images. This modification is documented but it is a badly faded photocopied document and I'm probably not going to be able to follow it properly. DJ, maybe some good photos of your board (under the MMU board you have) would help.

Anyway, that's what's going on. DJ, we can probably get yours going though. I have the pinouts for the cable (it's easy) and you'll need a Gotek with Flashfloppy firmware or an actual HXC2001 Gotek which is what I am using. They are just easier to deal with.

Santo
snuci
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Re: New Nabu 1600

Post by snuci »

Forget about what I said in the last comment. I got the Nabu 1600 booting CP/M 86. I tried to get it to work on a Gotek and a 5.25" floppy drive but no luck there, yet. The floppy is a quad-density floppy disk that is not high density, but not double density so this presents a bit of a problem. I am certain I can get it to work on a Gotek but have not yet. For now, a 3.5" floppy drive works but it is a specially jumpered one. This particular drive is an Amiga compatible floppy drive that is set for DS0. The combination of settings on the drive makes it work.
Nabu 1600 - CPM86-2 (small).JPG
Nabu 1600 - CPM86-3 (small).JPG
The QNX 1.15 disk image I have is not correct. It shows a directory structure but 99% of the disk is empty so I won't be able to get that going.

I did start on Xenix and it does through loading the first couple of diskettes but I think it's expecting the 10 MB hard drive that in the Mass Storage Unit (MSU) and fails to complete the booting process.

Leo, if you have any archived diskettes or would like them archived, let me know. I'd really love to try QNX.

For now, I will watch for a Western Digital WD1001 controller card. If I cannot find one in the next couple weeks, I can take apart another computer I have that has one but it's massive and I'd prefer to leave that one alone.

Santo
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DJ Sures
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Re: New Nabu 1600

Post by DJ Sures »

That’s great you have a floppy for it!!! Wow so cool to see it boot. If you get gotek working I’ll get one as well. I’m still leaning toward making a wd emulator for fun this winter. Keep the posts coming. It’s great to see it up!

Wonder if mpm has an 88 version to use multiple terminals
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LeoBinkowski
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Re: New Nabu 1600

Post by LeoBinkowski »

Ok, I just noticed this thread.

I have QNX 2 floppies, but I haven't examined them in years (of course!). Do you think greaseweasle SCP copies would be good enough? If not, we can try mailing again, but I'm not keen on doing that. Those are originals.

I actually have a bootable QNX 2 system as well on an IDE drive, and I can make bootable system floppies from it as well.

I have my Tour of the Universe source disks. I'm not sure what is on them, but I doubt they would boot the Burroughs Icon QNX 1.04. Probably just contain source.
snuci
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Re: New Nabu 1600

Post by snuci »

Hi Leo,

Hang onto the floppies for now. If you can find them, we'll walk through trying to archive them.

DJ,

I spent yesterday trying to make the 1600 boot from a Gotek and I could not make it work. However, if you have the correct 3.5" floppy drive, you can boot CP/M from floppy like above. The one I am using is a Chinon FZ-357. Below is a picture of the back of the floppy drive. Make sure you get this specific model with this jumper configuration. There is more than one version of the Chinon FZ-357 and each version has different jumper layouts so you need this specific one.
Working 3.5 floppy.JPG


Here is a close up of the drive jumpers. They need to be set up like this:
Floppy jumpers.JPG
Now, you need to make a cable. Luckily, the cable is simple to make. You will need a DB37 ribbon cable connector. Here is the one I used from Digikey. You also need an existing floppy ribbon cable. Make sure it has a 3.5" floppy IDC connector that can be straight with the DB37. It must NOT be after the twist in the cable, if it has connectors after the twist. You basically line up pin 1 of a floppy cable to pin one of the DB37. It is marked in little numbers on the face of the DB37 connector. Here is a quick diagram that I used to make sure the pins lined up.
Nabu_1600_floppy_cable_pinout.jpg
I use a vice to clamp on the DB37 onto the existing floppy ribbon cable and it works well to make sure the connector is on well.

Last thing you need to do is make a floppy. I used the CP/M ImageDisk image from Dave Dunfield's site here: http://dunfield.classiccmp.org/img42841/d/nabu1600.zip You will need to have a computer suitable to run ImageDisk with a 3.5" High Density floppy drive. Before you write the disk image, make sure Double Stepping is OFF. That is the only configuration setting you need to set other than which drive your 3.5" floppy is in.

Once you have the disk made, connect the cable, connect the drive (make sure you line up pin 1 and have a power supply for the floppy, insert the diskette and fire up the Nabu 1600. You should be all set.

If you have any issues, let me know. If you don't have a computer that can run ImageDisk, let me know and I can send you a couple of diskettes.

Hopefully, you can get yours running with a floppy drive.

Hope this helps,
Santo
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LeoBinkowski
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Re: New Nabu 1600

Post by LeoBinkowski »

Thanks Santo. I've had a busy month, so I'll wait searching for those floppies.
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