Cannot get ao486 to boot VHD with MS-DOS 6.22

danbee
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Joined: Wed Oct 14, 2020 7:07 pm

Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by danbee »

Hi all,

I've just started trying to configure and use the ao486 core for my MiSTer, and I managed to get as far as booting MS-DOS 6.22 from the original floppy images and installing onto a blank VHD file.

Unfortunately the resulting VHD file will not boot, stopping at the "Booting from Hard Disk..." message. If I boot from the MS-DOS floppy I can change to c: and see all the files installed there, included a DOS directory and autoexec.bat and config.sys files. I'm not sure what's going on.

ao486_booting.jpeg
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danbee
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by danbee »

I should add that the VHD image is 500Mb
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YLFAndy
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by YLFAndy »

Did you run setup on DOS or did you just copy files? Did you use the 500MB blank drive from the repository or roll your own? What happens if you add dummy VHDs to the rest of the IDE devices? I know that some folks have had issues if some of the IDEs are unpopulated. (I know these probably seem like really simple and obvious things, but it's worth checking)
danbee
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by danbee »

Thanks for your response YFLAndy. I went through the proper MS-DOS setup process and let the installer format the drive. The blank VHD was one I downloaded from a link on this forum somewhere. Not sure how to roll my own, but I guess a file of zero's will do? I also can't find any VHD's in the repo. Perhaps I'm looking in the wrong place?

I also checked the md5 sums of the MS-DOS disks I downloaded just to make sure I had the right ones.

I'll try the dummy VHD files in other slots.
danbee
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by danbee »

The blank VHD I used came from this thread: viewtopic.php?f=13&t=981&p=11619&hilit=vhd#p11619

Ok, just did a test with a 10MB zero byte file as my starting VHD and I got a booting system! I'm gonna try and remake my 500MB install the same way.
ash2fpga
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by ash2fpga »

I followed along parts* of flynnsbit's video. (*Windows VHD Creation, ao486 fdisk, ao486 format)

I grabbed the DOS 7.1 floppy image from the video, and ran fdisk and format from it. I then installed DOS 6.22 from installer floppy images. I did copy over the CD-ROM and mouse drivers from the DOS 7.1 floppy, though. It has been working OK for my DOS games and programs so far.

Repartitioning with fdisk and reformatting may have been able to fix the 500MB vhd perhaps.
flynnsbit
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Re: Cannot get ao486 to boot VHD with MS-DOS 6.22

Unread post by flynnsbit »

you can just go grab my boot disk from the exo package out on archive.org. It's a 9mb zip, search for ao486. But it sounds like you used windows to format the vhd or didn't use the fat32gui formatter. You don't have to do the MiSTer dance back and forth with the vhd to format it if you use the fat32gui formatter. https://github.com/flynnsbit/scripts/bl ... at-x64.Exe

Hope that helps get you going.
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