Editing Psion Series 5mx Pro

{{Infobox computer
| name         = Psion Series 5mx Pro
| image        = [[File:Psion Series 5mx Pro.jpg|250px]]
| caption      = A German-market Psion Series 5mx Pro
| developer    = Psion PLC
| manufacturer = Psion PLC
| type         = Clamshell palmtop / PDA
| cpu          = Psion "Windermere" SoC with ARM710T core, 36 MHz<ref name="wuffs" />
| memory       = 24 MB or 32 MB RAM, part of it holding the operating system; 128 KB boot loader flash<ref name="psionex24" /><ref name="psionex32" /><ref name="psrom-bl" />
| storage      = Internal RAM disk; CompactFlash slot, also the boot device<ref name="psrom" />
| display      = 640 × 240 touch-sensitive backlit LCD, 16 greyscales<ref name="wp" />
| sound        = Speaker and microphone<ref name="wp" />
| dimensions   = 170 × 90 × 23 mm<ref name="wp" />
| weight       = 354 g including batteries<ref name="wp" />
| os           = EPOC Release 5, loaded into RAM from CompactFlash (<code>Sys$rom.bin</code>)<ref name="psrom" />
| predecessor  = [[Psion Series 5mx]]
| model        = German market only<ref name="psrom" />
}}
The '''Psion Series 5mx Pro''' is a variant of the [[Psion Series 5mx]] made by Psion PLC. It has no operating system in ROM: a small boot loader loads EPOC into a reserved area of RAM from a CompactFlash card, so the operating system can be upgraded by replacing a file.<ref name="wp">[https://en.wikipedia.org/wiki/Psion_Series_5 "Psion Series 5"], Wikipedia. Retrieved 2026-09-30.</ref><ref name="psrom">Bs0Dd, [https://github.com/explit28/Psion-ROM "Psion-ROM: Stock / Patched / upgraded ROM files for old Psion devices"], GitHub, README section "Psion Series 5mx PRO". Retrieved 2026-09-30.</ref> It was sold only in the German market and is rare.<ref name="wp" /><ref name="psrom" />

Apart from the boot arrangement the Pro is a 5mx. It has the same case, screen, keyboard, screen ribbon and hinge mechanism, and the [[Psion Series 5mx]] pages apply to it.<ref name="wuffs" /><ref name="pitc">[https://pointinthecloud.com/2025-10-13-154800.html "Repairing a Psion 5mx handheld computer to add to my collection"], Point in the Cloud, 13 October 2025. Retrieved 2026-09-30.</ref>

== History ==

The 5mx Pro was released only for the German market, and Psion issued no English operating system for it. The English <code>Sys$rom.bin</code> images available today were built from the standard 5mx ROM. The known German builds are version 1.05 (265), 1.05 (273) and 1.05 (319).<ref name="psrom" />

Because the Pro loads its operating system from a file, copies of the 5mx operating system image were available for study long after the machines went out of production. In 2019 Ash Wolf built the WindEmu emulator for the 5mx from <code>Sys$rom.bin</code> images, without owning a machine. The work led to MAME's <code>psion5</code> driver, reimplemented by Ryan Holtz.<ref name="wuffs">Ash Wolf (Ninji), [https://wuffs.org/blog/building-a-psion-emulator "'16 Shades of Grey' - Building a Psion/EPOC32 Emulator"], 27 December 2019. Retrieved 2026-09-30.</ref>

== Architecture and processor ==

The Pro uses the same Windermere system-on-chip as the 5mx, with an ARM710T core at 36 MHz.<ref name="wuffs" /> In place of the 5mx's mask ROM it has a 128 KB boot loader in an AT29LV010A flash chip. The Windermere runs in its alternate test-ROM mode on the Pro, which remaps the address space so that the boot loader flash sits at address 0 and the CompactFlash (PCMCIA) and ETNA controller move to different addresses from the 5mx.<ref name="psrom-bl">Bs0Dd, [https://github.com/explit28/Psion-ROM/blob/main/Tools/Dumping%205mx%20PRO%20BootLoader/README.md "Dumping Psion 5mx PRO BootLoader"], Psion-ROM repository, GitHub. Retrieved 2026-09-30.</ref><ref name="wuffs" /> Boot loader versions 1.08 and 1.09 are known. They contain several languages, chosen by values in a serial EEPROM, but all show a German welcome screen.<ref name="psrom" />

== Memory and storage ==

Pros were sold with 24 MB and with 32 MB of RAM.<ref name="psionex24">Psionex, [https://psionex.co.uk/en/product/pda/series5/models/s5mx-24mb-pro-de.html "Psion Series 5mx Pro, 24MB, German specification"] (SKU S5MX_24MB_PRO_DE). Retrieved 2026-09-30.</ref><ref name="psionex32">Psionex, [https://psionex.co.uk/en/product/pda/series5/models/s5mx-32mb-pro-de.html "Psion Series 5mx Pro, 32MB, German / Deutsch"] (SKU S5MX_32MB_PRO_DE). Retrieved 2026-09-30.</ref> Part of the RAM holds the loaded operating system; on a 24 MB machine about 14 MB is left free.<ref name="psionex24" /> A standard 5mx has 8 or 16 MB with the operating system in ROM.<ref name="wuffs" />

=== Booting ===

The boot loader expects a file named <code>Sys$rom.bin</code> in the root of the CompactFlash card and loads it into RAM.<ref name="psrom" /> The file is about 10 MB.<ref name="wuffs" /> With no card and no operating system in RAM, the machine does not appear dead: it shows a German prompt, "Bitte CompactFlash-Card einlegen oder serielle Verbindung herstellen" ("insert a CompactFlash card or make a serial connection"), and waits for a card or for the operating system to be sent over RS-232 using YMODEM.<ref name="consuming">Improbulus, [https://www.consumingexperience.com/2008/06/psion-5mx-psion-5mx-pro-tips-sysrombin.html "Psion 5mx & Psion 5mx Pro tips: sys$rom.bin & operating system installation etc"], ''A Consuming Experience'', June 2008. Retrieved 2026-09-30.</ref><ref name="psrom" /> Typing <code>about</code> at this prompt shows the boot loader version.<ref name="psrom-bl" />

A Pro bought without its card therefore shows this prompt on every cold start. Copying <code>Sys$rom.bin</code> to a CompactFlash card and inserting it is enough to start the machine.<ref name="consuming" /> Removing all power loses the loaded operating system as well as the user's data, so the card has to stay available.<ref name="consuming" /> See [[Psion Series 5mx Pro Troubleshooting Guide]].

== Display, sound and input ==

The display, touch panel, keyboard, speaker and microphone are the 5mx parts: a 640 × 240 backlit LCD with 16 greyscales and a resistive touch panel.<ref name="wp" /><ref name="wuffs" /> A 5mx Pro screen assembly has been fitted to a standard 5mx in a documented repair, which makes Pros with dead boards a source of parts.<ref name="pitc" />

== Documentation ==

Psion's ''Series 5 Service Manual'' (November 1997) covers the Series 5. The 5mx and 5mx Pro use the same case and hinge mechanism, so its disassembly procedure applies. It is hosted here as [[Psion Series 5 Service Manual]].

== General maintenance ==
{{Main|Psion Series 5mx Pro General Maintenance}}
Maintenance is the same as for the 5mx, with one addition: the CompactFlash card holding <code>Sys$rom.bin</code> is part of the machine and needs a backup copy.

== Troubleshooting ==
{{Main|Psion Series 5mx Pro Troubleshooting Guide}}
A Pro showing the German CompactFlash prompt is not faulty; it needs its operating system file. Hardware faults are those of the 5mx.

== Hinge and screen cable ==
The Pro has the same chassis, hinge wires and screen ribbon as the 5mx. See [[Psion Series 5mx Hinge Repair]] and [[Psion Series 5mx Troubleshooting Guide]].

== Related pages ==

* [[Psion Series 5mx]]
* [[Psion Series 5mx Pro General Maintenance]]
* [[Psion Series 5mx Pro Troubleshooting Guide]]
* [[Psion Series 5mx Hinge Repair]]
* [[Psion Series 5]]
* [[Psion Series 5 Service Manual]]

== References ==

<references />

{{Navbox-Psion|state=collapsed}}

[[Category:Psion]]