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The Official Nabu PC Floppy Disk Controller thread

BlueIn2Red said:
FWIW I've already tried loading a valid (created with FORMAT on the NABU) HFE file in the HxC software, then exporting it as a raw image. This raw image can be read ok by cpmtools. I then load this raw image back into the HxC software (using the settings from post #141) and export it again as an HFE, but that HFE doesn't then work on the NABU (shows a corrupt directory listing).
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Per my post here, once the HFE is converted to a raw image all track format data is lost, only the sector 'user data' is retained. Converting it back to a HFE file won't recreate the lost data that is required by the NABU.
 
BlueIn2Red said:
I see, thanks. So is there really no way to do this then?
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Yes you should be able to do it with a lot of in between steps.
  1. Use HxC to export an HFE as a raw image.
  2. Use cpmtools to add new files to your raw disk image.
  3. Import raw disk image into HxC.
  4. Export image into kryoflux stream.
  5. Copy a valid track0.0.raw from one of snuci's kryoflux streams over the one you exported in step 4.
    1. For this you should not what type of disk image you are using (SSDD, DSDD, 3.5 DSDD)
  6. Load modified kryoflux stream from step 4 into HxC
  7. Export as new HFE image
The main issue is that the data CP/M needs to determine disk type and layout is embedded in the non sector area of track 0. This means that when you convert an HFE image to a raw sector image you lose that information.
 
Hello. I received my nabu and also a set of pcbs to build a FDC.
Is there a list available with 3.5" drives that will work? I have a spare Amiga floppy but thought the connector isn't the same as a PC.
Also for the board to board ribbon cable could a 2x30 IDC ribbon cable be used?
 
I just finished building the NABU floppy controller and installing it in my system. It's working so far as being able to list the diskette directory using the utilities from the menu system. However, I cannot figure out how to boot from a floppy! The videos show a startup screen that queries the user for startup method, but I do not see that when I start or reset the box. Do I need different firmware?
 
I am writing an Applesauce 'a2r' file to the diskette, which should yield a bootable diskette. But, again, as I mentioned above: I'm never even seeing the boot selector. It just autoloads from the cycle server. Is it necessary to replace the stock EPROM in order to have the boot selector appear?
 
The a2r should work. I personally use an 8k EPROM and have used that for all of my testing. For me, I could not get the floppy drive to work with the stock EPROM but this was when I was having initial problems with the disk images. Perhaps someone can chime in if they've been able to use the stock EPROM or another 4k EPROM. I personally use: https://vintagecomputer.ca/files/Nabu/firmware/NabuPC-U53-8K-90037150-Ver-29-Leo-1.bin

Note that there is a motherboard trace that needs to be cut and a jumper added to use an 8K EPROM (as opposed to the stock 4k EPROM). You can find a picture of the modification on the lower part of this post: https://vintagecomputer.ca/nabu-pc-fdc/

Hope this helps.
 
shirsch said:
I am writing an Applesauce 'a2r' file to the diskette, which should yield a bootable diskette. But, again, as I mentioned above: I'm never even seeing the boot selector. It just autoloads from the cycle server. Is it necessary to replace the stock EPROM in order to have the boot selector appear?
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Yes. The original ROM doesn't know how to boot a disk.
 
shirsch said:
I just finished building the NABU floppy controller and installing it in my system. It's working so far as being able to list the diskette directory using the utilities from the menu system. However, I cannot figure out how to boot from a floppy! The videos show a startup screen that queries the user for startup method, but I do not see that when I start or reset the box. Do I need different firmware?
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As has been said the original rev A rom that comes with these only allows booting over the cable network. The 8k roms Rev B and version 29 will support floppy booting, but require you to update a solder jumper on the main pcb to enable 8k boot rooms. If you don't want to bother with that you can update your rom to use the 4k version 14 or version 17 roms that also support floppy booting.
 
Ok, one step forward - two steps back. With the labomb EPROM I'm seeing the boot selection menu. But, the system hangs at random intervals when accessing the diskette. Most of the time it boots to the A> prompt, but locks after typing a few commands. It always leaves the drive selected when going brain-dead. I already swapped out the FDC and data separator chips with no change in (mis)behavior. During periods when it decides to be operational the 'check' command cheerfully reads all tracks and reports no bad sectors. Similarly, format runs to completion when it decides to work. I've tried two different floppy drives and a Gotek with no differences seen in the problem.
 
shirsch said:
Ok, one step forward - two steps back. With the labomb EPROM I'm seeing the boot selection menu. But, the system hangs at random intervals when accessing the diskette. Most of the time it boots to the A> prompt, but locks after typing a few commands. It always leaves the drive selected when going brain-dead. I already swapped out the FDC and data separator chips with no change in (mis)behavior. During periods when it decides to be operational the 'check' command cheerfully reads all tracks and reports no bad sectors. Similarly, format runs to completion when it decides to work. I've tried two different floppy drives and a Gotek with no differences seen in the problem.
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The boot ROM (patched or otherwise) is out of the picture once the disk is booted into cp/m. So lock-ups after entering a few commands, or format working occasionally, etc... would suggest that you have a hardware issue, be it with the floppy controller or the NABU itself.
 
Ok, so this is very odd. In a previous message I mentioned seeing frequent lockups when accessing diskettes or the Gotek emulator. All of these attempts were against 5.25" diskettes and images. Last evening I switched to 3.5" images on the Gotek and I cannot make it fail no matter what I do. 100% reliable. If I go back to the 5.25" version of CP/M, nothing but problems. The image files all come from Grant's web site. To reiterate: The 5.25" images fail when the a2r is written to media using an Applesauce or when the corresponding HFE is loaded under flashfloppy on a Gotek. I tried several different diskettes and two different drives. Would appreciate any theories about the cause for this problem.

I had previously swapped out both the 1797 FDC and the data separator chip with no change in behavior.
 
shirsch said:
Ok, so this is very odd. In a previous message I mentioned seeing frequent lockups when accessing diskettes or the Gotek emulator. All of these attempts were against 5.25" diskettes and images. Last evening I switched to 3.5" images on the Gotek and I cannot make it fail no matter what I do. 100% reliable. If I go back to the 5.25" version of CP/M, nothing but problems. The image files all come from Grant's web site. To reiterate: The 5.25" images fail when the a2r is written to media using an Applesauce or when the corresponding HFE is loaded under flashfloppy on a Gotek. I tried several different diskettes and two different drives. Would appreciate any theories about the cause for this problem.

I had previously swapped out both the 1797 FDC and the data separator chip with no change in behavior.
Click to expand...

For what it's worth, I have not been able to boot the 5.25" gotek image from Grant's site either. Another user that has been testing my cp/m 2.2 hasn't been able to boot it either. It tried re-creating the image, but wasn't successful. Pretty sure there is an issue with it, but the the 3.5" image works fine.
 
Yes, that's the image file I wrote to diskette. The similarly named HFE also failed. I have a Kryoflux... Somewhere. But before I dig for it, here's another interesting bit of information: While fiddling around with the system, I used the Applesauce application to convert the A2R of that 5.25" boot disk to HFE. Lo and behold, *that* HFE works just fine in the Gotek and does not misbehave at all. So, I'm starting to suspect that the flux timings are right on the edge.
 
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