atar wrote on 2026-02-06, 14:09:

Oh, the World is small. 😀 The PReP world is even smaller. If the machine is really PReP I'm not surprised you can not boot from a Debian 4 CD. I think this was only possible on CHRP machines. What VGA do you have? Do you have a serial line terminal?

Well, Debian 4 CD actually has a PReP kernel, so it should be bootable (there's also this thread showing that someone has had limited success with it.) The VGA card that came with it is a Matrox Mystique 220P (see pictures), with PowerPC-specific BIOS, I would assume - judging by the sticker, it is an official IBM FRU. Yes, obviously I have a plethora of methods of getting a serial terminal from this machine 😜 I suppose I could also try booting in text mode, if the kernel is configured to output messages to the serial TTY, but it still doesn't help that the firmware is not particularly chatty about what is going on...
BTW also attaching photos of the mystery SciTex SFL-PCI optical interface card.

If you have S3 864, you can try this floppy:
https://web.archive.org/web/20210928192322/ht … _2.2.23_with_fb

With any other graphics, it very probably would look like under QEMU, launched like this:

1 qemu-system-ppc -M 40p  -monitor stdio -bios q40pofw-vga.rom  -device floppy,drive-type=144,drive=floppyA -blockdev driver=file,node-name=floppyA,filename=carolina_bootimage_2.2.23_with_fb  -vga cirrus 

atar wrote on 2026-02-06, 15:15:

If you have S3 864, you can try this floppy: https://web.archive.org/web/20210928192322/ht … _2.2.23_with_fb […]
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If you have S3 864, you can try this floppy:
https://web.archive.org/web/20210928192322/ht … _2.2.23_with_fb

With any other graphics, it very probably would look like under QEMU, launched like this:

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1 qemu-system-ppc -M 40p  -monitor stdio -bios q40pofw-vga.rom  -device floppy,drive-type=144,drive=floppyA -blockdev driver=file,node-name=floppyA,filename=carolina_bootimage_2.2.23_with_fb  -vga cirrus 

The attachment carolina-fb.png is no longer available

I've actually ordered an S3 Trio64V+ 86C765, planning to replace the BIOS on it and try

lolo799 wrote on 2026-02-06, 15:05:

From the SuSe 7.1 manual from my previous post: […]
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From the SuSe 7.1 manual from my previous post:

The attachment 20260206_155808.png is no longer available

The attachment 20260206_160058.png is no longer available

Note that I don't have a RS/6000 but I do have an interest in PPC Linux.

Yeah, that mentions installing on CHRP machines, but mine is a PReP one, so those steps would not apply. The firmware does support reading iso9660, though, so there is a possibility to specify which file on disk to use as bootcode, I guess I'll mess around with that a bit. Will also try booting from the floppy as well, will see how that goes.

For Matrox you probably have to build your own kernel. Unfortunately I can not test it with QEMU - there is no Matrox emluation. But, if you can get a serial attached to it, try SuSE: https://web.archive.org/web/20210402194053/ht … e-7248-boot.img then you should see the following output on a serial console:

Feliksas wrote on 2026-02-06, 15:24:

Yeah, that mentions installing on CHRP machines, but mine is a PReP one, so those steps would not apply. The firmware does support reading iso9660, though, so there is a possibility to specify which file on disk to use as bootcode, I guess I'll mess around with that a bit. Will also try booting from the floppy as well, will see how that goes.

The 7.1 compatibility list states:
-Use of SuSE Linux possible:
RS/6000 43P Model 140 (special Kernel in 7.1-ppc CD1/unsorted/prep) so it should work with your unit.

Feliksas wrote on 2026-02-06, 15:17:

I've actually ordered an S3 Trio64V+ 86C765, planning to replace the BIOS on it and try

For linux you probably can even keep the bios, it's not used anyway. The screen would just stay dark before the kernel is loaded. Concerning V+ I'm a bit pessimistic, about the video bios though. I vaguely remember making an universal bios for 64V and V+, but I think I were forced to do it because 64V+ didn't exist in a wild nature. Or maybe AIX did not support it? I remember having to fake the PCI id, so that AIX thought that my passed-through 86C765 is a 86C764.

lolo799 wrote on 2026-02-06, 15:40:

The 7.1 compatibility list states:
-Use of SuSE Linux possible:
RS/6000 43P Model 140 (special Kernel in 7.1-ppc CD1/unsorted/prep) so it should work with your unit.

Nice! Then it maybe even supports the Matrox card.

Yay, I've had success of booting from the SuSe floppy disk, and the kernel there does, indeed, support the Matrox card. The boot process just froze at first (see screenshot), but it turned out that it doesn't like when more than 5 RAM sticks (640 MB) is installed - after removing the 6th stick it booted successfully all the way to the RAM disk floppy prompt. The 2.2 boot image for Carolina didn't seem to work at all - no output neither in the serial console, nor on the screen. Also ordered S3 864, wouldn't hurt to have a wider selection of hardware to experiment with.

Also tried loading Debian again with serial terminal connected, looks like it crashes at the very beginning in a weird way (see second screenshot).

Huge success! Managed to get into SuSe 7.1 installer 😀 Will try installing it now. I wonder if there is version 7.3 somewhere in the wild?

Yeah...spoke a bit too soon. First of all, I was installing SuSE 7.1, which has kernel 2.2 bundled, while booted from a disk meant for SuSE 7.3 (which has kernel 2.4, it seems). The installation failed to properly install the kernel package k_prep (as I've found out later, that might have been due to installer creating a too small PReP boot partition, I'll verify that later), the system booted into a graphical environment with KDE, but the kernel modules were missing, and after a reboot, the hard disk was not bootable. The 2.2 kernel that comes on the 7.1 install disk doesn't boot properly, no matter how it is loaded - directly from the floppy, or from CD with Yaboot - it just drops into machine monitor 😒 But at least I could get a graphical desktop up and running for a brief moment, that's progress 😀 Would be nice to find the PPC version of SuSE 7.3 installation media somewhere - looks like only x86 PC version is readily available...

Did you use the special kernel for the Model 140 from the first disc?

I've never seen a copy of SuSe 7.3 for PPC for sale despite searching somewhat regularly.

lolo799 wrote on 2026-02-07, 08:19:

Did you use the special kernel for the Model 140 from the first disc?

Yeah, I loaded it from the Open Firmware prompt, and it dropped to machine monitor just the same. Although, I will try writing it directly to floppy, since I'm not entirely sure, that the firmware did what I asked it to do, and loaded the specified file instead of the default kernel.
I'm also suspicious that the kernel image in 43p_140 directory has a .chrp extension, while we have established that this is a PReP machine.

EDIT: Attempt to load that kernel directly from floppy was not successful

Winner, winner, chicken dinner 😀 Phew, that was one hell of a journey...

Congrats on success!
BTW, since you have a serial console and an access to the ofw prompt, it might be a good idea to dump the machine and the Matrox roms. Or are they already available somewhere on archive.org?

atar wrote on 2026-02-07, 18:39:

Congrats on success!
BTW, since you have a serial console and an access to the ofw prompt, it might be a good idea to dump the machine and the Matrox roms. Or are they already available somewhere on archive.org?

I'll have to do a little research on that, as in what addresses are those available at, at least. Technically, I could just desolder them and do a direct dump, but there is probably an easier, software way 😀 Looking at the firmware update image, it looks like it is encrypted or at least obfuscated, but I'd wager that it is stored as is on the ROMs themselves.

It also should be possible to get the onboard Crystal Audio chip working in Linux, since there is cs4232 driver module available, but it doesn't seem to be ISA PnP (or, rather, the firmware already initializes it in the POST phase to play the jingle), so I'll need to determine where its IO base is.

For the roms, considering the matrox one is pci, it should be easily found using lspci and some parameters like -vv, maybe add some grep Matrox

Feliksas wrote on 2026-02-07, 20:03:

I'll have to do a little research on that, as in what addresses are those available at, at least. Technically, I could just desolder them and do a direct dump, but there is probably an easier, software way 😀 Looking at the firmware update image, it looks like it is encrypted or at least obfuscated, but I'd wager that it is stored as is on the ROMs themselves.

If you get to OFW boot prompt it's really easy.
show-devs

and then
dev /<rom-device from show-devs above>
.properties

would give you the addresses. OFW uses forth language, so after that a forth one-liner would dump it

Feliksas wrote on 2026-02-07, 17:19:

Winner, winner, chicken dinner 😀 Phew, that was one hell of a journey...

Nice job!
How did you make it work?

lolo799 wrote on Yesterday, 07:34:

Feliksas wrote on 2026-02-07, 17:19:

Winner, winner, chicken dinner 😀 Phew, that was one hell of a journey...

Nice job!
How did you make it work?

Well...I've found a very helpful resource here 😀
Important - I had to leave only 256 MB of RAM for the install process to be successful, otherwise it tries to access data beyond ramdisk boundary and crashes. (probably need to adust the ramdisk_size kernel argument)
First step was to load the 2.4.19 kernel onto a floppy and patch its boot args with preptool, and then load it from OFW prompt. It will then boot and request a floppy with the RAM disk, as usual.
When ramdisk is loaded, it would then read a bigger ramdisk from CD and start the installer. I chose the graphical X11 version.
An important note here - the installer will create a PReP boot partition type 41, BUT it will format it as ext2 for some reason and mount it as /boot, and k_prep package will just install the kernel and yaboot there. The installation will fail, as the package needs at least 5MB on the /boot partition, but the PReP partition created previosly is only 4MB. Not to worry, we don't need that 2.2 kernel anyway, the installer will bring up the system from the new root and continue installing.
At this point, I switched to the second text TTY, zeroed out the PReP partition, copied preptool and kernel image from the floppy to the root dir, dd'ed the kernel image to the PReP partition and then patched the boot args on it with preptool to set the new root (/dev/sda3 in my case). I also brought up the network and sent the modules tarball over with netcat and unpacked the modules where they belong, also fixing permissions.
Then I just waited quite some time for installer to eat up the first 4 CDs and install everything I requested, rebooted the system, set the boot drive in the firmware to be the first SCSI drive I installed the system to - and voila, we are in business!