Psion Series 5mx Pro
 | |
| A German-market Psion Series 5mx Pro | |
| Specifications | |
|---|---|
| Developer | Psion PLC |
| Manufacturer | Psion PLC |
| Type | Clamshell palmtop / PDA |
| CPU | Psion "Windermere" SoC with ARM710T core, 36.864 MHz[1][2] |
| Memory | 24 MB or 32 MB RAM, part of it holding the operating system; 128 KB boot loader flash[3][4][5] |
| Storage | Internal RAM disk; CompactFlash slot, also the boot device[6] |
| Display | 640 × 240 touch-sensitive backlit LCD, 16 greyscales[7] |
| Sound | Speaker and microphone[7] |
| Dimensions | 172 × 89 × 24 mm (5mx)[2] |
| Weight | 350 g with batteries (5mx)[2] |
| OS / Firmware | EPOC Release 5, loaded into RAM from CompactFlash (Sys$rom.bin)[6] |
| Predecessor | Psion Series 5mx |
| Model no. | German market only[6] |
The Psion Series 5mx Pro is a variant of the Psion Series 5mx made by Psion PLC. It has no operating system in ROM: a small boot loader loads EPOC into a reserved area of RAM from a CompactFlash card, so the operating system can be upgraded by replacing a file.[7][6] It was sold only in the German market and is rare.[7][6]
Apart from the boot arrangement the Pro is a 5mx. It has the same case, screen, keyboard, screen ribbon and hinge mechanism, and the Psion Series 5mx pages apply to it.[1][8]
History
The 5mx Pro was released only for the German market, and Psion issued no English operating system for it. The English Sys$rom.bin 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).[6]
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 Sys$rom.bin images, without owning a machine. The work led to MAME's psion5 driver, reimplemented by Ryan Holtz.[1]
Architecture and processor
The Pro uses the same Windermere system-on-chip as the 5mx, with an ARM710T core at 36.864 MHz.[1][2] In place of the 5mx's mask ROM it has a 128 KB boot loader in an AT29LV010A flash chip. The Windermere runs in its alternate test-ROM mode on the Pro, which remaps the address space so that the boot loader flash sits at address 0 and the CompactFlash (PCMCIA) and ETNA controller move to different addresses from the 5mx.[5][1] Boot loader versions 1.08 and 1.09 are known. They contain several languages, chosen by values in a serial EEPROM, but all show a German welcome screen.[6]
Memory and storage
Pros were sold with 24 MB and with 32 MB of RAM.[3][4] Part of the RAM holds the loaded operating system; on a 24 MB machine about 14 MB is left free.[3] A standard 5mx has 8 or 16 MB with the operating system in ROM.[1]
Booting
The boot loader expects a file named Sys$rom.bin in the root of the CompactFlash card and loads it into RAM.[6] The file is about 10 MB.[1] 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.[9][6] Typing about at this prompt shows the boot loader version.[5]
A Pro bought without its card therefore shows this prompt on every cold start. Copying Sys$rom.bin to a CompactFlash card and inserting it is enough to start the machine.[9] Removing all power loses the loaded operating system as well as the user's data, so the card has to stay available.[9] See Psion Series 5mx Pro Troubleshooting Guide.
Display, sound and input
The display, touch panel, keyboard, speaker and microphone are the 5mx parts: a 640 × 240 backlit LCD with 16 greyscales and a resistive touch panel.[7][1] A 5mx Pro screen assembly has been fitted to a standard 5mx in a documented repair, which makes Pros with dead boards a source of parts.[8]
Documentation
Psion's Series 5 Service Manual (November 1997) covers the Series 5. The 5mx and 5mx Pro use the same case and hinge mechanism, so its disassembly procedure applies. It is hosted here as Psion Series 5 Service Manual.
General maintenance
Maintenance is the same as for the 5mx, with one addition: the CompactFlash card holding Sys$rom.bin is part of the machine and needs a backup copy.
Troubleshooting
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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Ash Wolf (Ninji), "'16 Shades of Grey' - Building a Psion/EPOC32 Emulator", 27 December 2019. Retrieved 2026-09-30.
- ↑ 2.0 2.1 2.2 2.3 Psion Computers PLC, Psion Series 5mx User Guide (1999), p. 191 (specification, standard 5mx). Hosted on this wiki: File:Psion Series 5mx User Guide (1999).pdf.
- ↑ 3.0 3.1 3.2 Psionex, "Psion Series 5mx Pro, 24MB, German specification" (SKU S5MX_24MB_PRO_DE). Retrieved 2026-09-30.
- ↑ 4.0 4.1 Psionex, "Psion Series 5mx Pro, 32MB, German / Deutsch" (SKU S5MX_32MB_PRO_DE). Retrieved 2026-09-30.
- ↑ 5.0 5.1 5.2 Bs0Dd, "Dumping Psion 5mx PRO BootLoader", Psion-ROM repository, GitHub. Retrieved 2026-09-30.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Bs0Dd, "Psion-ROM: Stock / Patched / upgraded ROM files for old Psion devices", GitHub, README section "Psion Series 5mx PRO". Retrieved 2026-09-30.
- ↑ 7.0 7.1 7.2 7.3 7.4 "Psion Series 5", Wikipedia. Retrieved 2026-09-30.
- ↑ 8.0 8.1 "Repairing a Psion 5mx handheld computer to add to my collection", Point in the Cloud, 13 October 2025. Retrieved 2026-09-30.
- ↑ 9.0 9.1 9.2 Improbulus, "Psion 5mx & Psion 5mx Pro tips: sys$rom.bin & operating system installation etc", A Consuming Experience, June 2008. Retrieved 2026-09-30.