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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
05547 Crash/Freeze Critical (emulation) Sometimes Apr 26, 2014, 02:32 Sep 21, 2023, 00:57
Tester maclover490 View Status Public Platform MESS (Official Binary)
Assigned To Resolution Fixed OS Windows Vista/7/8 (64-bit)
Status [?] Resolved Driver
Version 0.153 Fixed in Version 0.154 Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary MESS-specific 05547: ct486: System locks up when attempting to boot MS-DOS 6.22
Description When I attempt to boot MS-DOS 6.22 install disk 1, the system locks up.
Steps To Reproduce Boot from MS-DOS 6.22 disk 1
Additional Information This only happens with the ct486 driver, both at486 and at586 can boot from this disk without any issues

It seems that I can prevent the freeze by pressing F8 and manually choosing "Y" to all of the config.sys/autoexec.bat prompts.

The OS will also boot correctly from a hard disk, only the install floppy freezes
Github Commit
Regression Version
Affected Sets / Systems ct486
Attached Files
There are no relationship linked to this issue.
User avatar
Apr 29, 2014, 15:40
edited on: Apr 29, 2014, 15:40
I was able to with 0.153 binary (64-bit) create a new HD, set BIOS, load DOS boot and install MS-DOS 6.22 with that version:

1) Clear old NVRAM in nvram\ct486 folder

2) chdman createhd -o pchard.chd -chs 1024,16,63 -c none
Create HD for use - ~504MB

3) mess64 -hard1 pchard.chd]
Boot system, first time will prompt to enter bios. Auto DETECT the HD using the option in the main menu, ESC when done. STANDARD settings, Assign floppy to 1.44mb 3 1/2" to A:. ESC. ADVANCED settings, Change boot order from C:, A: to A:, C, ESC - then save your bios/EXIT
It is best to after the failed booted to stop/restart MESS save the NVRAM, this will also allow you to add the -flop1 command for the msdos622 disk.

4 mess64 -hard1 pchard.chd -flop1 disk1.img
This will boot the system using A: as the main boot drive - You should see STARTING MSDOS on the screen and within a minute or so, you should get the option to install. Just follow the on screen instruction, hitting ENTER when required and using FILE MANAGER when required to change disks (disk2,disk3), installed all 3 disks from the install. Once complete, you can simply unmount the A: floppy image and let the system reboot from the install. You should then get autoexec.bat working and end up at a C: prompt.

I tested 0.153 and current SVN from today 04/29, the both seemed to work.
User avatar
Apr 29, 2014, 17:45
edited on: Apr 29, 2014, 17:57
I followed your instructions and it still freezes at "Starting MS-DOS..." unless I use F8 and single-step through config.sys and autoexec.bat on the install floppy.

Using this trick, I was able to fully install DOS 6.22 and it boots fine from the hard disk without the need to use F8
User avatar
Apr 29, 2014, 22:36
With current SVN, it works without any issues that I can see. I did experience some oddness when I attempted to duplicate on 0.153 64-bit from where sometime the Floppy drive reading would hang up and fly into the weeds, as they say.

So, I'll confirm behavior and mark it fixed for 0.154.
User avatar
Jun 19, 2022, 04:54
edited on: Jun 19, 2022, 04:55
The issue maclover490 raised occurs in 0.244. It freezes at "Starting MS-DOS". I wasn't sure how to apply the F8 workaround. I tried at486 and it works as stated. Apologies for adding a note to an old report.
User avatar
Sep 21, 2023, 00:45
I ran into this exact scenario a week or so ago. I had found this resolved bug report, and the procedure involving F8 worked the same way maclover490 described.

I just remembered that I wanted to at least comment on this report about it. I just tried again a few moments ago and it still happens.

Currently the only way I can get the MS-DOS 6.22 setup disk (crc32:69d8cfdd) (sha1sum:30b4b2e99b26b0e5e7dbe61b9892e45fe751a3e8) to load all the way into the setup program using the pc/ct486.cpp driver is with this F8 trick.

MAME Version: 0.258
User avatar
Sep 21, 2023, 00:57
I also tried deleting all the files in nvram/ct486 and allowing MAME to recreate them. This made no difference.