Windows NT on mmr4000le (MIPS R4000 CPU)

These are pre-made hard disk images for Windows NT 3.1, 3.51, and 4.0. All these images were recorded with MAME 0.284 with the commit c80d828c cherry-picked on top of the 0.284 release.

In order to recreate the disk, you must have the Windows NT 3.1, 3.51, and 4.0 installation CD-ROMs, specifically the images defined in the MAME generic_cdrom software list. At a minimum, the following files are needed:

• winnt31/en-us windows nt 3.10.528.1 1994.chd
• winnt351/en-us windows nt workstation 3.51.1057.1.chd
• winnt40/en-us windows nt workstation 4.0.1381.2.chd

Images from other sources may not reflect these releases, and the input recordings will likely desync.

Running the installation input

In order to recreate the disks, hard disk images with the CHS geometry set to 1040,16,63 must be created.

1. Have the Windows NT images mentioned above available in some path.
2. Create an empty CHD: chdman createhd -o winnt31.chd --chs 1040,16,63
3. Run MAME’s mmr4000le driver with these parameters: mame mmr4000le -nonvram_save -nvram_directory /dev/null -harddisk ./winnt31.chd -cdrom winnt31 -playback winnt31.inp -nothrottle -exit_after_playback

Change the file names, especially for the -cdrom and -playback parameters for the other versions as desired.

On vanilla MAME versions 0.274 through 0.284, you will need to specify a file path to the Windows NT installation image. Starting from commit c80d828c, MAME has a generic_cdrom list and the jazz.cpp driver is connected to it, making the shortname usable.

Running a pre-installed hard disk

The mmr4000le driver requires some configuration in order to boot one of these images and they are saved in the system’s nvram files. The paths to the operating system loader changes in each release, but generally from a clean nvram boot:

1. Select Run setup
2. Select Initialize system
3. Select Set default configuration
4. You can press Enter through all the options. The main thing you might want to change is screen resolution, it defaults to 1280×1024. A smaller resolution might be more comfortable.
5. Select Set default environment
6. The boot partition partition must be set to 2. You can press enter on the other options.
7. Semi-optional: select Set time. The clock sometimes starts up with an invalid triple-digit hour and Windows NT might boot up thinking the date is far in the past or far in the future (I’ve seen both the years 1601 and 6781 when ignoring this step).
8. Select Return to main menu
9. Select Manage startup
10. Select Add a boot selection
11. Press enter for Scsi Hard Disk 0 Partition 2
12. Enter the osloader path. It defaults to \os\nt\osloader.exe and this is fine for Windows NT 3.1. Change to \os\winnt351\osloader.exe for Windows NT 3.51, \os\winnt40\osloader.exe for Windows NT 4.0.
13. Answer No to “Is the operating system in the same partition as the osloader?”
14. Select Scsi Hard Disk and SCSI ID 0. Enter the partition number 1.
15. For Windows NT 3.1 and 4.0, the operating system directory \winnt is fine. For Windows NT 3.51, change it to \winnt35.
16. Optional: Enter a name for the boot selection. It default to having “Windows NT” filled out, and you may just accept that.
17. Select No to “Do you want to initialize the debugger at boot time?”
18. Select Return to main menu
19. Select Exit

From this point, the computer will reboot and you should have a Windows NT entry to boot.

Windows NT requires pressing Ctrl-Alt-Delete before logging on. Depending on operating system and window manager, the literal sequence might not be possible. I suggest rebinding a key so that you can press them. I prefer to set my real right-control key to be the same as left-alt, then I can press both control keys and delete.

Methodology and motivation

While MAME from versions 0.219 through 0.284 already contain hard disks for Windows NT 3.5, 3.51, and 4.0 on the “jazz” computer (Microsoft’s codename for their own MIPS workstations), they predate MAME’s inclusion of the operating system installation media itself, making the source a little unknown. They were also installed in 2020 and the file systems reflect that with 2020 dates throughout the system.

Preferring to have provably reproducible images, I have set out to make new images, with the date and time set to be identical to the files on the Windows NT installation CD-ROMs themselves, this is assisted by recording with MAME under the faketime command. Having file dates in the 1990s looks a lot more natural for these versions than a 2020 date.

I initially wanted to use NTFS for the operating system partition on all the versions, but I found that only NT 3.1 accepts this configuration for some reason, 3.51 and 4.0 insist on being FAT, even with the ARC files existing on an independent partition. For consistency, all these operating systems are installed onto FAT. Each was given only a half-gigabyte drive, but with a dearth of software available for Windows NT on MIPS, it should not an issue. A secondary hard disk can also be installed to expand the utility as needed.

Emulation was halted after the GUI installation phase. The first boot of the system in Event Viewer will reflect the time you start the emulator up, rather than the installation time. The winmsd program can reflect the true installation time.

At the time of writing (January 2026), I have been unable to successfully install Windows NT 3.5, neither with the image included in MAME nor multiple alternative CDs, including the one with debugging symbols not stripped out. I do not believe this to be an issue with the installation media, but with MAME’s emulation. How the existing 3.5 hard disk was created, I do not know; it is possible MAME has suffered a regression, but strange that the other versions work.

No server versions

MAME includes installation CD-ROMs for the server editions of Windows NT, and they can be installed on mmr4000le. As of January 2026, the driver does not support networking and providing server pre-installs would wind up with an operating system effectively like the client counterpart, only with worse foreground application performance.

If and when mmr4000le becomes capable of networking, it will be desirable to set server configuration yourself and a pre-made disk image may not be useful.