I know RM has a bit of a following in the UK so no I don't think its a silly idea.
Screen will be the hardest, does it have a VGA out? That'll get you out of trouble at least for the short term

RetroAddict wrote on 2025-05-25, 16:28:

Hey all,

Well I've been sitting on this machine for quite a while, after winning it for putting on a bid just so I'd get alarts when the auction was going to end. The machine works (partially), but I need to get a replacement for the blessed Dallas that's contained within to have it fully functional. I also need to repair the screen which has I believe cracked at some point as it has a red spider effect going across it.

Can anyone tell me if it was common for these machines which are actually rebadged Siemens-Nixdorf machines to be painted? This one has a textured far more beige than you'd expect at its age and some of it is flaking off?

Wow you got quite a deal on that, RM stuff usually attracts a lot of attention and bids.

Regarding the orange spider effect, if it's not cracked then that's called LCD rot and my theory is that air has got into the liquid crystal segment of the panel, with mono and DSTN screens that always looks like an orangey red blob or fractal kind of shape. Lots of similar stories here: https://forum.vcfed.org/index.php?threads/ora … screen.1247018/
I posted at the end that my screen which had LCD rot starting at one edge fixed itself while in storage. I'm pretty sure at this point that it's air inside the panel where the seal isn't keeping the liquid crystal in a vacuum anymore and some actions like flexing (mine started with a drop) cause air to get sucked in.

I've not seen an RM laptop up close since using them at school so no idea on the paint, but I can confirm they're not rebadged Siemens-Nixdorf machines, they're really all made by Quanta - the FCCID is HFS-QC338 which is a 386sx laptop:
https://fcc.report/FCC-ID/HFSQC338/
See, the siemens is the same and has the FCCID listed on the underside label - these are not my pictures, but they show the label well:

I made an extensive post on the later Quanta HFS-LK4 platform of 486sx laptops: AST Bravo NB 4/25s Laptop - Quanta LK4 - HFSLK4
And was going to make a post about the earlier Quanta HFS-SK4 platform, which is also a 486sx laptop but pre-PCMCIA. The RM-NB400 is a Quanta SK4 laptop 😀

These Quanta laptops weren't bleeding edge and have some interesting design choices at times - like on the SK4 you have to remove the screen to remove the palm-rest to work on the RTC battery or replace the HDD. But they are reliable and because they used the DS1287 type of RTC they're not ruined like a lot of other laptops that used NIMH batteries for their RTC clock.
The capacitors don't go bad as severely as Toshibas from that era can do, so they tend to work once the RTC battery is fixed.
Personally what I've done to fix that is strip the laptop, desolder the DS1287 and then cut up the casing of the DS1287 so I can disconnect the original battery and solder in wires for a CR2032 coin cell holder.

However I wonder if you'll hit the same problem I did where the hard drives that can be fitted are hard-coded, so swapping storage out for compact flash isn't an option (unless you reflash a custom BIOS with the HDD table modified, yes it works). Hopefully your hard drive works 😀
The laptop is definitely worth fixing I think, good luck.

Thermalwrong wrote on 2025-05-26, 14:16:

Wow you got quite a deal on that, RM stuff usually attracts a lot of attention and bids. […]
Show full quote

RetroAddict wrote on 2025-05-25, 16:28:

Hey all,

Well I've been sitting on this machine for quite a while, after winning it for putting on a bid just so I'd get alarts when the auction was going to end. The machine works (partially), but I need to get a replacement for the blessed Dallas that's contained within to have it fully functional. I also need to repair the screen which has I believe cracked at some point as it has a red spider effect going across it.

Can anyone tell me if it was common for these machines which are actually rebadged Siemens-Nixdorf machines to be painted? This one has a textured far more beige than you'd expect at its age and some of it is flaking off?

Wow you got quite a deal on that, RM stuff usually attracts a lot of attention and bids.

Regarding the orange spider effect, if it's not cracked then that's called LCD rot and my theory is that air has got into the liquid crystal segment of the panel, with mono and DSTN screens that always looks like an orangey red blob or fractal kind of shape. Lots of similar stories here: https://forum.vcfed.org/index.php?threads/ora … screen.1247018/
I posted at the end that my screen which had LCD rot starting at one edge fixed itself while in storage. I'm pretty sure at this point that it's air inside the panel where the seal isn't keeping the liquid crystal in a vacuum anymore and some actions like flexing (mine started with a drop) cause air to get sucked in.

I've not seen an RM laptop up close since using them at school so no idea on the paint, but I can confirm they're not rebadged Siemens-Nixdorf machines, they're really all made by Quanta - the FCCID is HFS-QC338 which is a 386sx laptop:
https://fcc.report/FCC-ID/HFSQC338/
See, the siemens is the same and has the FCCID listed on the underside label - these are not my pictures, but they show the label well:

The attachment Siemens-PCD-3NSX-HFSQC338.jpg is no longer available

I made an extensive post on the later Quanta HFS-LK4 platform of 486sx laptops: AST Bravo NB 4/25s Laptop - Quanta LK4 - HFSLK4
And was going to make a post about the earlier Quanta HFS-SK4 platform, which is also a 486sx laptop but pre-PCMCIA. The RM-NB400 is a Quanta SK4 laptop 😀

These Quanta laptops weren't bleeding edge and have some interesting design choices at times - like on the SK4 you have to remove the screen to remove the palm-rest to work on the RTC battery or replace the HDD. But they are reliable and because they used the DS1287 type of RTC they're not ruined like a lot of other laptops that used NIMH batteries for their RTC clock.
The capacitors don't go bad as severely as Toshibas from that era can do, so they tend to work once the RTC battery is fixed.
Personally what I've done to fix that is strip the laptop, desolder the DS1287 and then cut up the casing of the DS1287 so I can disconnect the original battery and solder in wires for a CR2032 coin cell holder.

However I wonder if you'll hit the same problem I did where the hard drives that can be fitted are hard-coded, so swapping storage out for compact flash isn't an option (unless you reflash a custom BIOS with the HDD table modified, yes it works). Hopefully your hard drive works 😀
The laptop is definitely worth fixing I think, good luck.

Thank you for the extensive and thought out reply! I've got a battery soldered to the dallas chip now and the machine will boot but intermittently. It is complaining about a floppy error and at times a keyboard error which is a pain in the rear! Having torn the machine down, it has 8mb ram, an AMD 386 cpu and an intel 387 co-processor. The current drive is a tidbit drive, looking on the nimbus fansite, the 386 they have photos of seems to have a different version of the board. This bios does only allow you to select from 20 to 160mb as the hard drive size.

I've a soft spot for the nimbus stuff from school, I have a P2-400 nimbus here that actually ran the central heating system when it was retired from active use up until it was given to me around four years ago. I also have a p3-866 machine but these were after my time and so it doesn't really hold the value to me, that the P2 machine does.