I finally managed to dump the rom of my Psion Revo (German version). I first thought it was 16MB, which caused strange crashes of PsiROMx with memory leak (RAM file system corruption). But the info menu of the device showed that it was only 8MB, which address range dumped ok (in 2 parts because it has also only 8MB RAM).https://github.com/explit7/Psion-ROM/issues/1
This is how I revived my Psion Revo:https://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=122153#Post122153
The dump program and many other Psion roms can be found here:https://github.com/explit7/Psion-ROM/
For dumping I used my Win98SE system (mainboard DFI K6-BV3+/66, AMD K6-3+@550MHz). Strange is that the docking station only works on COM2 port but the PDA is not recognized on COM1 (23pin? with adapter) despite the RS232 mouse works on both. The wallwart power supply is only for charging the battery - unplug it when fully charged to avoid overheat. To copy files on the Psion, you need PsiWin. My version 2.3.3 seems to temporary corrupt the explorer when copying files onto the PDA, so e.g. file extensions are not displayed anymore (despite enabled in options) and once even the desktop icons got termporary resorted into 2 vertical stripes. After reboot everything works again. By pressing menu key, the dump program PsiROMx shows a menu "advanced"(?) in that the memory range for the dump can be changes (important for PDAs with small RAM).
If you search more info about Psion software, this German language forum is one of the few still intact links.https://www.psionwelt.de/psionwelt-hauptforum.html
But the software download section seems dead. Much of it can be found here:https://jonasbark.de/folder/
Someone also makes money of a CD with software (I don't own it).https://www.netogram.com/psionfreeware.html