MiSTer FPGA Forum

Hello, I'm new to MiSTer, and I've played around with a number of computer cores (including AO486) successfully, but I've not been able to get the PCXT core to boot. I've tried several BIOSes, including the ones I generated using the provided Python scripts, but I'm never able to boot into FreeDOS or MS-DOS. I'm not sure what I'm doing wrong at this point. I've attached pictures of one of my attempts, using the pcxt_pcxt31.rom. It seems to freeze at 256 KB in the memory test. The Tandy rom I tried also gave memory errors, others don't but then are unable to boot or freeze when they attempt to boot.

I'm using a MiSTer Pi megapack. I've run memtest for a couple of hours successfully, and other cores work fine, so I suspect the problem is user error rather than the hardware, at least at this point. Any suggestions of things to try would be very welcome!

Try booting from a floppy. You may have mixed results with hard disk images. Remember, the original IBM PC did not even support a hard drive and the XT was very picky about what it supports. The XTIDE BIOS ROM does help a lot in that regard, but you're still dealing with finnicky old hardware. Booting from a floppy first, then accessing the hard disk image from there will rule out the question of whether your image file can be accessed at all.

Another option would be to just create an empty raw image file, boot from a DOS floppy and do the partitioning and formatting of the hard disk from there. That'll ensure your core "gets" what you're trying to do and things will probably boot up from the hard disk image after you remove the floppy. Ancient versions of PC/MS-DOS don't have installers. You just create partitions using FDISK, format the partition using FORMAT C: /S so that the partition gets the OS system files. Finally you create a C:\DOS directory (MKDIR C:\DOS) and copy whatever you want from your floppy into that directory: COPY A:\*.* C:\DOS

..hope this helps!

You can check my reply to similar query, maybe it will help: https://www.misterfpga.org/viewtopic.php?p=78456#p78456

Also, you can try running one of the hdd images from this thread: https://www.misterfpga.org/viewtopic.php?t=5368

Thanks for your responses. I should have mentioned I've already tried a couple of bootable floppies to no avail. The BIOSes that don't freeze during memory check will freeze once they try to boot from floppy. They don't give an error or anything.

I did see the response you linked, akeley. I tried its suggestions but no luck. The pcxt_pcxt31.rom freezes at 256KB, but the pcxt_xtsergey.rom fares slightly better, and will at least recognize and try to boot disks. I've tried a couple of other hard disk images with DOS installations on them, they also cause the core to freeze. One froze so hard I couldn't bring up the OSD menu, and another lost video signal (or at least went to a video mode that my LCD didn't like). I also tried booting an image I found in the other thread you suggested, no luck, just froze.

One interesting thing is that if I select a non-bootable floppy image, it does give me an error stating that the disk isn't bootable. So it doesn't like booting DOS for some reason?

Unfortunately I've not made any progress since my last post. I went through the posts suggested above again, regenerated the BIOS files from script, tried other BIOS roms, but I can never make it into DOS. I even tried a 360K boot disk in case disk size was the issue. The only real clue I have is the memory error message that the Tandy BIOS gives me, so I attached a screenshot. I ran memtest for a couple of hours, 150MHz, no errors, so that doesn't seem like the problem. I also confirmed that the core's RBF file on the SD card matches the latest release in the git repo. I'm stumped.

It took me a while to get to my MiSTer but I posted a ZIP file for you containing a BIOS ROM file that works + a HDD image of MS-DOS 3.31 that also works. I just tested on the core that's on my box at the moment, which is the 230902 version but that's just a random coincidence.

CPU speed: 4.77, system model PCXT, CGA graphics: YES, Hercules graphics: No, PCXT 1st Video: CGA.

ftp://ftp.area536.com/doscontainer/dist ... orking.zip

I hope this helps!

Thank you for sharing the ZIP. I tried those files with the settings you mentioned, but unfortunately it still freezes at "Booting C>>C", to the point where the OSD won't come up and I have to reboot the Mister.

Were you using these files on a Mister Pi or a DE10-nano based setup?

I have a DE10-Nano.