Psion Series 3mx
The Psion Series 3mx, announced in July 1998, is the last and by a wide margin the fastest of the 16-bit SIBO palmtops. It is essentially an upgraded Series 3c — same case, same screen, same applications — with a NEC V30MX running at 27.684 MHz, roughly 3.6 times the clock of the 3a and 3c.[1]
 | |
| A Psion Series 3mx | |
| Specifications | |
|---|---|
| Developer | Psion PLC |
| Manufacturer | Psion PLC |
| Type | Clamshell palmtop / PDA |
| Released | July 1998 |
| Discontinued | Final SIBO palmtop |
| CPU | NEC V30MX (80C86-compatible) @ 27.684 MHz |
| Memory | 2 MB ROM; 1 MB or 2 MB RAM |
| Storage | Two internal Solid State Disk (SSD) slots |
| Display | 480 × 160 monochrome LCD, backlit on all models |
| Sound | Microphone, loudspeaker and CODEC; 8 kHz 8-bit recording, DTMF auto-dialling |
| Dimensions | 165 mm × 85 mm × 22 mm |
| Weight | 275 g including batteries |
| OS / Firmware | EPOC16 (SIBO), with OPL |
| Predecessor | Psion Series 3c |
| Successor | Psion Revo |
| Model no. | Matte silver metallic finish; CR2025 backup cell |
It arrived after the 32-bit Psion Series 5, as a last outing for the SIBO line rather than a replacement for it.[1]
What changed from the 3c
edit| Change | Detail |
|---|---|
| Processor | NEC V30MX at 27.684 MHz, replacing the V30H at 7.68 MHz |
| ROM | 2 MB, up from 1 MB |
| Serial | Fast serial port, up to 115 kbit/s — roughly double the 3c |
| Backlight | All 3mx models are backlit, where the 3c's was a late and largely US option |
| Backup cell | CR2025, not the CR1620 used by the Series 3, 3a and 3c |
| Finish | Matte silver metallic paint, against the 3c's dark grey |
| External power | 9 V, 250 mA |
| SSD door sensing | A pair of angled microswitches, replacing the 3c's PCB tracks and door-hinge contact |
The backup cell change is the one to remember. A 3mx takes a CR2025 and the earlier machines take a CR1620 — different diameter and different thickness. Fitting the wrong one is a common and avoidable mistake.[1]
Everything else carries over: the 480 × 160 screen, the 58-key keyboard with 9 touch-sensitive application keys, two internal SSD slots, an infrared port, 2 × AA cells and the same 165 × 85 × 22 mm case at 275 g.[2]
Sound
editThe 3mx has a microphone, a loudspeaker and a CODEC giving digital recording and playback at 8 kHz, 8 bits wide — 12 bits compressed to 8 — plus DTMF auto-dialling through the speaker.[2]
The SSD door microswitches
editThis is the 3mx's own characteristic fault, and it is worth understanding before you open one.
Where the 3c senses its SSD slot doors with PCB tracks and a small metal connector on the door hinge, the 3mx uses a pair of microswitches set at an angle.[3]
The plastic tips of those microswitch buttons snap off — almost always because the motherboard was prised out with the SSD doors closed. The machine then reports "not ready" and refuses to see a pack in either slot, which looks exactly like a motherboard fault and has sent more than one owner chasing the wrong thing.[3]
Open both SSD doors before removing the mainboard. The repair, if it is already too late, is on the Psion Series 3mx Troubleshooting Guide.
Easter egg
editThe 3mx and the 3c contain a hidden melody and credits screen.[1]
Known problems
editThe family faults — hinge breakage, button bar failure, screen cable deterioration producing vertical lines[1] and the battery lead — plus the 3mx's own SSD door microswitches.
General maintenance
editTroubleshooting
editHinge repair
editSee also
edit- Psion Series 3 · Psion Series 3a · Psion Series 3c · Psion Siena
- Psion Revo — the 32-bit machine that took over the small-palmtop role
- Battery Refurbishment
References
edit- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "Psion Series 3", Wikipedia. Source for the announcement date, the V30MX processor and clock speed, the RS-232 speed increase, the RAM options, the matte silver finish, the CR2025 backup cell, the universal backlight, the infrared port and the Easter egg.
- ↑ 2.0 2.1 2.2 "Psion 3mx, Psion 5, Psion 5mx, Psion Revo and Psion Revo Plus specifications", netogram.com. Source for the 3mx ROM and RAM sizes, external power rating, backup cell, keyboard layout, CODEC sample rate and DTMF auto-dialling.
- ↑ 3.0 3.1 Richard Zealley, "Psion Series 3mx SSD door microswitch repair", Retro Coding, 25 May 2020. Source for the microswitch arrangement, the failure mechanism, the "not ready" symptom, the requirement to repair both switches, and the repair method.