Psion Series 5mx
 | |
| Two Series 5mx palmtops, one open and one closed | |
| Specifications | |
|---|---|
| Developer | Psion PLC |
| Manufacturer | Psion PLC |
| Type | Clamshell palmtop / PDA |
| Released | 1999 |
| CPU | ARM710T core in Psion's custom "Windermere" SoC @ 36 MHz |
| Memory | 8 MB or 16 MB RAM |
| Storage | Internal RAM disk; CompactFlash slot |
| Display | 640 × 240 touch-sensitive backlit LCD, 16 greyscales |
| Sound | Speaker and microphone, with a dictaphone function |
| Dimensions | 170 mm × 90 mm × 23 mm |
| Weight | 354 g including batteries |
| OS / Firmware | EPOC (ER5), later renamed Symbian OS |
| Predecessor | Psion Series 5 |
| Model no. | Also sold as the Ericsson MC218 |
The Psion Series 5mx is the 1999 development of the Psion Series 5, and for many people the high point of the whole Psion line: a genuinely pocketable clamshell with a touch-typeable keyboard, a 640 × 240 greyscale touchscreen, a proper multitasking 32-bit operating system, and ten to twenty hours of use from two AA cells.
Its defining mechanical feature is the sliding keyboard clamshell designed by Martin Riddiford of Therefore Design and protected by European patent EP 0766166B1: opening the lid slides the keyboard forward, counterbalancing the display and bracing it so that pressing the touchscreen does not tip the machine over.[1]
The Series 5 and the Series 5mx look almost identical, but their mainboards, screens and other internal components are different and not interchangeable.[1] That includes the screen ribbon cable — the part most likely to need replacing.
Hardware
[edit | edit source]Processor and memory
[edit | edit source]The 5mx is built around "Windermere", a custom system-on-chip Psion had made for it, containing an ARM710T core running at 36 MHz. The earlier Series 5 used an off-the-shelf Cirrus Logic CL-PS7110 with an ARM710a core at 18 MHz.[2]
The distinction matters: the T in ARM710T means the core supports Thumb and has different coprocessor 15 behaviour — one reason 5mx and Series 5 software and system images are not simply interchangeable.[2]
RAM is 8 MB or 16 MB. The operating system lives in ROM and user storage is a RAM disk, which is why the backup cell matters so much.
ETNA
[edit | edit source]ETNA is a bespoke Psion chip, present on both the Series 5 and the 5mx, that handles the CompactFlash and PCMCIA interface. It is essentially undocumented — even the Psion Linux developers who were given official documentation had nothing on it, and the OpenPsion code is full of constants captured from working machines.[2] For repair purposes the practical consequence is simple: a CompactFlash fault that is not the door switch, the connector or the card is not a component-level repair.
The PROM
[edit | edit source]The 5mx carries a small 128-byte serial PROM holding its serial number, its factory digitiser calibration and its real-time clock calibration. EPOC reads it by bit-banging GPIO pins and ETNA registers, sixty-four 16-bit words at a time, and validates it with an XOR checksum.[2]
This explains a repair-relevant behaviour: digitiser calibration is stored in two places. The factory values live in the PROM; the user's own calibration is stored in non-volatile memory and is lost if the machine loses all power.[3][2]
Display and digitiser
[edit | edit source]The panel is a 640 × 240 passive-matrix LCD, normally-white, with a separate resistive digitiser laid over it: a glass lower plate and a hardened plastic top plate, both printed with resistive ink, held apart by very small moulded bumps, with four connections sensing resistance across the X and Y axes. Each connects to the mainboard by a 22-way flat flexible cable.[3]
The LCD needs its supply rails enabled and disabled in a defined sequence so that no residual DC is ever left across the panel — DC causes the liquid crystal to drift and eventually damages its polarisation permanently.[3] That is why the machine re-initialises the display on every power-up, and why a half-powered machine can show odd artefacts.
The screen coordinate origin (0,0) is the top left of the LCD, not of the digitiser, so the silkscreened shortcut icons down the left-hand edge have negative X coordinates.[2]
Keyboard
[edit | edit source]The keyboard is a separate switch matrix assembly that slides out as the screen is opened, connected to the mainboard by a 22-way flat flexible cable in a 22-way ZIF connector — of which only 20 ways carry keys. The two outside pins are grounded to give the keyboard membrane a ground ring for ESD protection.[3] Key pitch is 12.5 mm, which is what makes the machine genuinely touch-typeable.[1]
Scanning is by column: the OS writes to a KSCAN register to select a column, and reads the rows from GPIO port A.[2]
What EPOC calls the hardware
[edit | edit source]The operating system reports its own component names, which occasionally confuse people reading the Machine Info screen:[2]
- Screen — LCD
- Power supply — APM 500
- Keyboard — LAP 53
Analogue measurements
[edit | edit source]Battery voltages and digitiser position are read through an ADC over SPI. The 5mx exposes four channels:[2]
| Channel | Identifier |
|---|---|
| Digitiser Y | 0x9093
|
| Digitiser X | 0xD0D3
|
| Main battery | 0xA4A4
|
| Backup battery | 0xE4E4
|
Power
[edit | edit source]The 5mx runs from two AA cells, typically giving 10–20 hours of use, with a lithium coin cell backup to preserve the RAM disk while the main cells are changed.[1]
The user reset switch is part of the backup battery's negative contact, reachable only by opening the backup battery cover and pressing it with a pointed instrument. Operating it vectors the CPU to a warm restart, and user data should survive.[3] A power-on (cold) reset is generated automatically by a voltage detector when the supply crosses a threshold, and it erases everything held in volatile storage.[3]
Removing both the main cells and the backup cell without external power connected will erase the internal memory.[3]
Variants and relatives
[edit | edit source]| Machine | Differences |
|---|---|
| Psion Series 5 (1997) | CL-PS7110 / ARM710a at 18 MHz, 4 or 8 MB. Same case design, different mainboard, screen and screen ribbon |
| Psion Series 5mx Pro | As the 5mx, but the operating system is loaded from a Sys$rom.bin file on CompactFlash rather than baked into ROM, so it can be upgraded
|
| Ericsson MC218 | A rebadged Series 5mx |
| Psion Revo / Revo Plus | Smaller, 480 × 160 screen, rechargeable cells, no backlight and no CompactFlash slot; reportedly also Windermere-based |
There was never a Series 4 — Psion skipped the number over concerns about tetraphobia in Asian markets.[1]
Software
[edit | edit source]The 5mx runs EPOC release 5 (ER5), the operating system that was later renamed Symbian OS. Bundled applications include a word processor, spreadsheet, database, agenda, contacts, email, a calculator, the OPL programming language, a Java virtual machine and the STNC HitchHiker browser; the Executive Edition added Opera 3.62.[1]
The OpenPsion project (formerly PsiLinux) supports Linux on the 5mx.[1] For working on a machine you cannot switch on, the WindEmu emulator and the MAME psion5 driver both emulate the 5mx accurately enough to be useful for checking behaviour.[2]
Documentation on this wiki
[edit | edit source]- Psion Series 5 Service Manual — Psion's own 46-page service manual. It covers the Series 5, but the 5mx uses the same mechanical platform, so the exploded views, part numbers, disassembly procedure and reassembly cautions all apply. The electronics sections do not.
General maintenance
[edit | edit source]Batteries, the CompactFlash and battery doors, the stylus catch, the case switch and the flat flexible cables are the routine concerns. See the Psion Series 5mx General Maintenance guide.
Troubleshooting
[edit | edit source]Two faults dominate: horizontal lines on the display from a cracked screen ribbon, and a broken hinge-wire hook in the chassis. Both are documented, and both are fixable. See the Psion Series 5mx Troubleshooting Guide.
Hinge and chassis repair
[edit | edit source]The plastic hooks that retain the spring hinge wires go brittle and break. A replacement inner chassis can now be 3D printed. See the Psion Series 5mx Hinge Repair guide.
Capacitors
[edit | edit source]The 5mx is not a recap candidate, and it is worth understanding why before opening one. See the Psion Series 5mx Capacitor Replacement Guide.
See also
[edit | edit source]- Psion Series 5 — the 1997 original
- Psion Organiser II — where Psion started
- Battery Refurbishment
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "Psion Series 5", Wikipedia. Source for the model history, the patent and designer of the sliding clamshell, the display and keyboard specifications, the physical dimensions, the Ericsson MC218 rebadge, the 5mx Pro, the absence of a Series 4, and the statement that Series 5 and 5mx internals are not interchangeable.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Ash Wolf (Ninji), "\"16 Shades of Grey\" — Building a Psion/EPOC32 Emulator", 27 December 2019. Source for the Windermere SoC and ARM710T identification, the CL-PS7110 in the Series 5, the ETNA controller, the 5mx hardware variant ID, the boot sequence, the 128-byte PROM contents and read method, the SPI/ADC channel identifiers, the digitiser calibration structure and defaults, the EPOC hardware component names, and the keyboard scanning arrangement.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Psion Series 5 Service Manual, Psion Computers PLC, November 1997. Hosted on this wiki as File:Psion Series 5 Service Manual (November 1997).pdf. Source for the circuit description, the keyboard and LCD/digitiser interfaces, the LCD power sequencing requirement, the reset behaviour, the exploded views and part numbers, the disassembly and reassembly procedure, the standby current figures and the Final Test fail codes. Written for the Series 5; the 5mx shares the mechanical platform but not the electronics.