Sunday, 1 June 2008

Psion 5mx & Psion 5mx Pro tips: sys$rom.bin & operating system installation etc

My beloved Psion 5mx, as those who know me know, is still my main portable computer (it's not just a PDA, it's not, it's not! More on Psion series 5 including a Linux project). I don't quite tuck it up in bed with me at night, but almost. An updated Psion is really what I want some insightful manufacturer to sell - c'mon, there's a huge untapped market for something like that.

Anyway, for the 2 & three quarters other people out there who are also still using the 5mx, I thought I'd document my precautions and tips and also, for my own future reference as I'd forgotten it, how to reinstall the OS on the 5mx Pro.

How to install the operating system (OS) on the Psion 5mx Pro

My 5mx recently went a bit wonky so I decided to use a Psion 5mx Pro I'd previously bought as a spare. As I back up my Psion regularly to my PC's hard drive, it normally takes less than half an hour to restore all my backed up files from PC to spare Psion.

Unfortunately I'd forgotten that the Pro is a bit different from the bare bones 5mx: you have to load its operating system into RAM! However, I got a bit of a clue when I inserted batteries into the spare 5mx Pro and got this exciting and illuminating message on the screen (for those of you who understand German - I don't, obviously!):

"Bitte CompactFlash-Card einlegen oder serielle Verbindung herstellen"

Even if you do know German, in fact that message isn't much help (calling for a CompactFlash card or serial connection, without telling you that you have to have certain files on the card or your computer first).

Luckily, this German Psionwelt webpage came to the rescue (English translation), to help me install the operating system on the Psion 5mx Pro.

I couldn't recall where my original CompactFlash card for that Psion had got to and I'd probably reformatted it anyway (their method 1).

What I finally did was their method 4, based on the instructions on that very helpful page. To save any other non-German speakers the troubleshooting time, here are the steps (assuming you already have the PsiWin software installed on your PC and have a backup of course):
  1. Find the Sys$rom.bin file - luckily it was still lurking on my PC hard drive (feel free to download my copy of the English Sys$rom.bin file if you wish, it's zipped - NB you need to rename it to Sys$rom.bin after you download and unzip it, or it won't work.)

  2. Copy it to CompactFlash card (see further below), using e.g. a USB card reader.

  3. Put it in the 5mx Pro (of course making sure the Psion is switched off first).

  4. Switch it on, and tweak your preferences and control panel to your usual settings.

  5. Connect Psion to PC with the serial cable (in fact I have a serial to USB converter cable) and restore the backup from PC - NB make sure the cable connection is enabled first (System screen, Tools menu, Remote Link set to Cable not Off); mine sometimes disables itself after a reset.

Note: I did try first to download romload.exe from the Psion 5mx Pro Support page (PsionWelt's method 2), but despite that support page claiming that the Language was English, I only had the choice of German and German. And my German is non-existent. Hence ending up with the method involving sys$rom.bin file on CompactFlash card.

General Psion 5mx tips

And here are my top tips & tricks for the Psion fan, to protect against the rare occasion when your Psion goes wrong, and what to do when it does:
  1. Get a spare Psion series 5 if you can (I have a spare 5mx and a 5mx Pro). It's easy to restore from backup to the spare if necessary.

  2. Invest in a CompactFlash card. I have a SanDisk 512MB and it works very well (I tried a 1GB card but it didn't work, I suspect half a gig is the biggest capacity of card that the 5mx can read/write to).

  3. Use the card! Make sure you store your main agenda, documents, contact databases etc on the card rather than the Psion's own C drive (System, Disk menu, change Current disk to D). Use the superb free Macro5 to speed access to agenda, contacts etc via the softkeys. That way if all goes haywire your precious data is on the card, not in the Psion memory to risk being lost on a reset.

  4. Save often - when I pause for thought while working on a document, I automatically hit Ctrl-s.

  5. Backup to PC regularly - with PsiWin (Windows-only as you'd expect from the name), it's a doddle and takes mere minutes. I backup at least once a week. And now, I also backup after I've made any major changes e.g. added a whole bunch of dates to my diary.

  6. Note your preferences in a checklist - not all your settings are backed up by PsiWin. I now keep a "Psion Checklist" document on the root of my CompactFlash card which, for ease of restoration, just lists my main settings (in Preferences and in the Control Panel) after a soft reset and a hard reset - e.g. in my case change default disk from C to D (the CompactFlash card), sort files by date, change it to my preferred zoom level, open Macro5, enable cable connection. A soft reset doesn't seem to affect Preferences or Control panel settings, luckily.

    For a hard reset I need to also tweak it to show hidden files & the system folder, make Enter open multiple files, set password & owner info, sounds, switch on/off when open/closing the case, and change the keyboard (repeat rate etc) and if necessary touchscreen settings.

  7. If things go wrong, don't forget soft reset. End of paper clip into the little hole by the backup battery when you open the backup battery compartment underneath. This seems to preserve some of my settings at least. Much more so than the hard reset (take out AAs and also the backup battery and replace them) which wipes out everything on the Psion but, fortunately, not what's on the card, and often works if the soft reset doesn't.

  8. If all else fails try POSltd (now called Club PDA it seems) who offer a Psion repair service by post and are very efficient and helpful - I've used them a couple of times over the years! Keep the cardboard box they send your Psion back in, if you ever need to use them again it's the best way to post your Psion to them.


Anonymous said...

Wow, there are still psion 5mx users that use the Psion as their primary portable computer, like I do! In fact, it's my primary computer, portable or not!

Some remarks on the article:
CF up to 2GB will work on the 5mx, but some CF's don't work. If you create 4 partitions on a 8GB CF (with Linux, Windows can't do that), that will work too.

For restoring the settings, don't use a document, but use the program sysback: it's free!

Because the device is so old, most software is now free. Take a look at,,,,,
And for questions and answers:


ScienceTeachings said...


Thanks for that. I just bought Psion 5MX and I use it all the time! I'm a Teacher & use it to produce worksheets, lesson plans and take minutes in meetings!

I'm trying (SO HARD to get Calligrapher for my 5MX but it's vanished from the web without a trace!)

If you have it, then please would you email me?

Please email me at or

Keep the Psion alive!


Improbulus said...

Thanks for the comments!

Anon, thanks also for your tips and links.

Matt, sorry I can't help as I don't have that software, but maybe someone else who comes across this post will be able to?

Yeah keep the Psion alive, us Psion fans must stick together!

ScienceTeachings said...


Thanks for your help. Just a note to say that I have got a 2GB CF card and have now put 4 partitions on it for use in the Psion! I had to partition it on Linux and just downloaded that on my XP system. Works better than XP did!

Can the Psion read 8GB? Let me know the details. Thanks.

All I have to do is find some Psion goodies to put on there!

Thanks again.


Anonymous said...

For those who are still looking for a replacement or a spare, I found a company that still sells these and at least includes a 30 day warranty.

lucy said...

Does anyone know if it is possible to use the internet or email 'wireless' (not using the Psion modem or an old model mobile phone) on a Psion 5mx?
I am thinking along the lines of a wireless CF card?