The Psion 3 FAQ


2.1 Hardware specifications

All Psion machines are based around the "SIBO architecture", which was developed to meet common goals which span the SIBO range, including Series 3.

Of paramount importance is low power usage. To this end CMOS circuits are used, the CPUs are static - meaning their clocks can be slowed down or stopped and restarted without impairing function, and the specially designed ASIC chips implement sophisticated power management, which always ensures that only those parts of the machine which are needed, are powered up. Power is provided by 2 AA batteries during normal operation. A Lithium backup battery, a CR1620, is provided which maintains memory during battery changes. A mains adaptor inlet is provided.

A system clock runs independently of the CPU even when the machine is "off". This allows it to keep time and to wake the machine up when (for example) alarms expire.

A six-pin outlet is provided, through which serial and parallel ports may be connected. This outlet has exactly the same signals as the two expansion ports (SSDs).

A sound system implements beeps on the Series 3 through a low power piezo-electric element at two volumes. On the 3a there is a more sophisticated system employing bi-directional digital-to-analogue conversion, a conventional speaker, and a microphone, which together support the recording and playback of digitally-recorded sound. Digital sound data is compressed and expanded between 8 and 13 bits by hardware in an ASIC using the Alaw algorithm during recording and playback respectively, at a sample rate of 8KHz. This performance conforms to the ISDN standard for digital phone systems. A Series 3 buzzer emulation is also available on the 3a.

For both machines, there are two expansion ports, also called SSD drives, into which RAM or EPROM memory modules may be placed.

The memory is split into two types: process and storage. Storage memory is only used for storing data. Process memory is the memory used by the processor. Programs run in this type of memory. Process memory is limited on all Psions to 512k maximum. There is no storage memory on Psions with 512k RAM or less. To be honest, this is a not a big problem, since the Psion implements a real good memory management and "windows" the memory needed for each application. In practice, this means that you can open several huge databases for example and only need 10k of memory for each one.

In tabular form, the differences are summarised below:

Item Series 3 Series 3a
PROCESSOR name V30H (80C86 compatible) V30H(80C86 compatible)
Bitwidth 16 16
Speed 3.84 MHz 7.68 MHz
video mem access 8 bit - half speed 16 bit - full speed
Type Monochrome LCD Monochrome LCD
Physical size 126 x 45 mm approx
Display size 240x80 480x160
Display depth 2 - black/white 3 - black/grey/white
Internal 128 or 256Kbyte 256Kb,512Kb,1Mb,2Mb
Expansion 2 slots = 16Meg max 2 slots = 16 Meg max
Size 16.5 x 8.5 x 2.2 cm (6.5" x 3.3" x 0.9")
Weight 275 grams including batteries
Output device Piezo beeper Loudspeaker
Capability variable pitched Beeps Any sound and DTMF [*]
Digital system
NONE DAC/ADC 8/13 bits
Sound recording
NONE 8K samples per second
Telephone dialler
DTMF capability DTMF capability

*Further sounds can be generated if a custom device driver is written

Via optional link Via optional link
Via optional link Via optional link
Installed in link pod In Psion 3a ROM
Max speed
9600 baud 19200 baud

Controls applications Upgraded on Series 3a
Database application Upgraded on Series 3a
Comprehensive document Upgraded on Series 3a
processing system

Personal management Major upgrades on 3a application
Clock and alarms manager Upgraded on Series 3a
World info database Cosmetic upgrade on 3a
Calculator Calculator Allowing OPL extension
Cosmetic upgrade on 3a SHEET [*]
Spreadsheet application
Speadsheet application available as add-on [*] built-in

*In the US, and latterly in the UK, the "Series 3s" includes the spreadsheet as standard (not for 128k models) SPELL CHECKER/THESAURUS add-on Only on 1/2Mb models * PATIENCE GAME add-on Only on 1/2Mb models * *Spell checker/thesaurus and patience game are apparently not available on all country specific 1/2Mb models (ie: not available for french nor german models!) OPL Programming application Series 3 compatibility mode also available.

2.2 What batteries does the Psion use?

Normal power is provided by two AA (also known as LR6) batteries. Standby power is provided by a small Lithium backup battery, a CR1620, which maintains system data during main battery changes or failure.

2.3 How long do the batteries last?

It all actually depends on what type of batteries you use. Here are the advantages and disadvantages of the different battery types:

Alkalines. These are the "normal" batteries and work well.

Carbon/Zinc. These batteries are cheaper than alkalines but of course don't last as long. Might be interesting if you can get them really cheap and are ready to change batteries often.

NiCad rechargeables. These proivde less energy than conventional batteries (reports suggest maybe half) and they fade rapidly once their charge is nearly gone, but - they are rechargeable, and so offer a cost effective alternative. Note that NiCads are NOT recharging while the machine is powered by the adaptor.

Lithium AA batteries. They are 30% lighter than alkalines, and they last longer, but they are more expensive. Recommended if you really need long battery life and in extreme conditions. These batteries have a very long shelve life.

The link causes high battery loadings, as does the sound system. Accessing the SSDs also increases power drain. Because of the static architecture, a busy CPU drains more power than a sleeping one, so compute-intensive tasks will burn power. For these reasons, it is difficult to quote battery performance exactly, but the table below summarises reports received on the net.

                           Alkaline            NiCad           Lithium

  Running time (Hrs)        40-100              20              65-100
  Power  delivered (mAh)    1500                800           1600-2700
  Price each (UKP)          0.5                                  4.5
  Comment                                                    30% lighter

The backup battery typically lasts 15 months.

2.4 Where can I find the backup battery?

It has been reported difficult to obtain these in the UK, so here is a small list to get you started. You should first check your local watch shop, since this is essentially a watch battery.

Sangers photographic, Birmingham 0121-523-4471
C.D. Zelley Ltd, Thetford 01842-755303
Apollo watch products, Tonypandy 01443-432474
Swains International, Hunstanton 01485-533393
Newey & Eyre Ltd, branches throughout the UK
Watchmaker supply, Oxford 01993-842442

2.5 Can I use an external power supply?

Yes, the Psion comes with a standard power outlet so you can use either the official Psion power supply or a general-purpose mains adaptor (which is cheaper). Negative polarity should be selected - ie the tip should be negative. The power supply should be able to deliver 150mA at 9V. The Psion adaptor has an indentation around the outer conductor near the tip which facilitates snug fit for improved reliability.

You can plug the external power supply in/out while the Psion is on. It will then immediately use the external power or batteries. The Psion also has an automatic turn off possibility. This is very useful if you often forget to turn it off! One of the choices for this auto turn off feature is "If no external power", so you can safely use it on external power and it will not turn itself off anymore until you unplug it again.

2.6 Can I upgrade my Solid State Disk (SSD)?

Flash SSDs are cheaper than RAM SSDs because the filesystem doesn't actually allow you to recover deleted space on them. Even if they're cheap compared to real RAMs, they're still quite expensive because they're not manufactered on a big scale (they're Psion proprietary). This tempted several people to accomplish upgrades. It has been successfully done, but I decided not to describe it here for several reasons:
It wouldn't be fair to Psion PLC. Think about it: it would prive them of rightly owned money for their R&D and that wouldn't make us many friends, would it?
The chips you need aren't easy to find.
It is quite easy to do for a trained electronician, so that person wouldn't need any instructions anyway. If you don't have the expertise, don't even think about it!

2.7 Can I upgrade my internal RAM?

The big question when the 1/2Mb models came out: can I upgrade my 512k to a 2Mb model? Well, sorry, but the answer is no. The new models use a new ROM to access the extra memory. Psion PLC does not offer upgrades for new models either. The best solution is to sell your old model and get a more recent one. But, if you own a 128/256k or 1Mb model, upgrading it is just a matter of adding more RAM to it. Psion PLC can do this for you, contact them about it.

For the time being, process memory is limited to 512k on every model and you cannot add more whatever you do.

2.8 Can I change the keyboard?

A lot of people buy their Psions in the UK because of the huge price difference compared to their own country. This is not a problem in itself if you just remember that you will be getting the UK version, thus the UK keyboard, applications and manual. This also the reason why so many people would like to change the keys of their keyboards. For these people, there is no simple solution. The keyboard map is not just a file held in RAM, so basically, you're stuck with your keyboard, but there are workarounds to this:

    In many applications, you can enter special characters (for example - foreign characters not found on the keyboard) by holding down control, then typing the three digits of the ASCII code for the character (ASCII code table on page 246 of the User Guide). This works for all characters in the range 32 to 255. Some lower codes are used for control purposes.
    There is also a quicker way to enter letters with accents, umlauts etc. CONTROL can be used with the number keys as a character modifier directive. For example, "2" is the "Add an Umlaut" command, so you can hold down CONTROL then press "2" and "o" to get an umlauted "o" (ö). Most numbers are chosen as convenient mnemonics: 2 has " above it - which looks like an Umlaut; 3 has \ which simulates a grave accent; 5 has ', which produces an acute accent, etc. See the Character set section of the user guide for details.
    Use Tom Dolbilin's excellent Macro System package to assign a "macro" to a regular key, thus emulating another key.

2.9 Can I use a big (normal) keyboard?

Yes, if you have Tom Dolbilin's Macro System installed, there is a macro called "BigKeys" which actually reads the serial port and sends the key to the HWIM application you're currently running. Unfortunately, it will not work with normal OPL applications. On the other hand, you will still need another computer to send the keys over the serial line, so it really isn't what people are looking for!

Keith Baker has made a little interface for just a normal keyboard (without the need for another computer) connected to the Psion using the 3-Link interface. Note that it will not work with OPL applications either.

2.10 How do I make a serial link?

Unfortunately you can't. The reason being that there is not only hardware but also software in the 3-Link. The 3-Link is not just a level converter, so a MAX232 or the like would not work! The extension port uses a high speed proprietary protocol (undocumented).

2.11 What is this "soap on a rope" thing?

The "soap on a rope" is simply another name for the 3-Link. It is named like that because of it's ressemble with (guess what ;-) the well known soap on a rope.

2.12 How do I print with my Psion?

There are a number of ways you can print from your Psion
Through the parallel link, connect your Psion directly to your printer but do not turn the link on in the system screen!
Through the serial link - use the printer setup dialogues appropriately and do not turn the link on in the system screen!
Use PRINT SETUP to select printing to a file called REM::C:\LPT1. Run MCLINK on your PC, and activate the link from the Psion. Now all print requests will go through the link to the PC printer, and MCLINK is available for file transfers - better than MCPRINT. This solution also works with RCOM. On some PCs running Windows, it may be better to print to LPT1.PRN, which traverses through the DOS/Windows device drivers slightly differently. (by Daniel Senie)
Use RFM (see elsewhere in the FAQ) to make Psion drives visible, then use a conventional PC tool to print files from the Psion.

2.13 Can I take my Psion through an X-Ray machine?

Yes you can without fear. Nowadays the airport's X-Ray machines are harmless to palmtop computers and diskettes (hopefully ;-). In any case, if you're really not assured, ask to pass it seperately.

2.14 Can my Psion wipe out magnetic data?

Yes it can! Be careful with the underside of your Psion because it is actually the speaker which contains a magnet whom is responsible for such problems. Credit cards and other magnetic data seem to be the easiest "victims" of the magnet. Check out the first page of your User Guide for Psion's own warning about this. You can try the paperclip test which consists of taking a pile of paperclips and placing the Psion on top of it. Lifting the Psion will typically take 5 paperclips with it!

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