Psion 3a palmtop computer review

The finest miniature 8 bit computers of their time

An early Psion handheld computer.


This is a 1993 British designed clamshell palmtop. Its rounded body helps it feel, subjectively, the smallest of the keyboard palmtops, at 165mm (6.5") by 85mm (3.3") by 23mm (0.9") thick, giving a volume of 323 cc. The weight is 275 gram. I was pretty impressed by the small size, and it does fit in most pockets. The curved surfaces of the Psion mean its actual volume is actually considerably less than the maximum dimensions indicate.


Two Alkaline AA batteries are required, but not supplied, and these fit in the hinge area, similar to the HP OmniGo 100. A 1620 Lithium backup battery is supplied. You can use rechargeable batteries, with possibly some considerable loss of battery life, and less reliable detection of battery life. There is provision for an external 9 volt DC power supply, which will light an LED on the Psion, but will not charge rechargable batteries. The Series 3a had a MAxim MAX616 DC-DC converter which allowed voltages between 5.5 and 12 volts as input. Auto shutdown modes can be different for battery vs external power, a point some manufacturers unaccountably neglect.


The display is a 480 pixel by 160 pixel LCD, a total of 76,800 pixels. The display size is a relatively small 124mm by 41mm, or 130mm diagonally (I measure the active display area, not the total display size). This is not a great proportion of the case size, which is rather disappointing in such a small machine. LCD contrast adjustment is via software from the keyboard.

I'm very impressed with the display, which is readable even under poor light. This is the best palmtop display I've used to this date. It is even better than the Sharp PC3100. Note however that some Sharp Zaurus, the most recent Apple Newton 130 and the new Psion 3c all have a backlit display, and these may be even more readable in really poor light.

Four font sizes appear to be available, zoomed under hotkey control, giving displays of 9 lines by 44 characters, 11 lines by 49 characters, 12 lines of 50 characters, and a tiny 17 lines of 75 characters. The maximum character count of 17 lines of 75 characters used mostly 7 pixel high by 5 pixel wide characters on a 9 by 6 matrix. I counted these using numeric characters. As the standard system text and display uses a proportional font, you may get a few more characters on each line.


As with most palmtops, the qwerty keyboard occupies almost all the body size. The key spacing is a tiny 11mm (a standard IBM computer keyboard is 19mm), even smaller than the HP OmniGo 100 (13mm). The keys themselves are larger, more typewriter style, and this contributes to an impression of spaciousness that seems lacking in the HP OmniGo 100. There are 58 keys, no function keys, but there are 8 application buttons. No numeric keypad. The cursor keys are in inverse T, with Home, End, PgUp and PgDn accessed via a function shift key.


The processor is a 7.68 MHz NEC V30H (80C86) compatible. Nothing exotic here at all. Despite this, most programs work quickly.


ROM is one megabyte. Ram memory is 1 megabyte, of which about 800 kb are available for user material. This is much better than most palmtops, which use up over 500k for their own system, rather than making it available to the user.

Storage Devices

Both SRAM and Flash Solid State Discs are available. These are Psion made, and not compatible with anything else in the entire universe. Their major advantage is they are smaller than PCMCIA cards. Their disadvantages include not being compatible, being vastly more expensive than PCMCIA, being slower because they are linked via a serial protocol, and not having anywhere near as extensive a range as PCMCIA cards provide. I think Psion blew it totally on these gadgets (although, to be fair, PCMCIA didn't exist when Psion started, and would not have been sufficiently compact to fit into their design).

While there is no provision for an external floppy drive or hard disk, a serial floppy disk, and an external SSD drive are made by third parties. The cost is enormous, a general problem with non-standard gadgets. You can use a cheap gadget to read and write Psion SSD disks using an MS-Dos PC parallel port.

Other Input and Output Devices

There is a non-standard six pin serial connector. This is covered by a "push-in" shell surrounding the pins. A very tricky idea, which would be even more impressive if it didn't sometimes jam in the "in" position. Psion sells a expensive "soap on a rope" style cable, with the other end being a PC style 9 pin D serial connector. Like most of the palmtop makers, Psion make out like bandits on their cables, but the Psion one does have more in it than just a set of wires (a custom ASIC, EEROM, etc).

The Psion port (and SSDs) are reputed to use a 1.536 Mb/sec clock with a 12 byte frame to clock serial data. People have managed to make an IBM PC parallel port read and write SSD cards by bit bashing two lines as clock and data.

The model I checked was S/N FBC4187493.

User Manuals

An excellent A5 size 290 page User Guide is supplied. 20 chapters, the table of contents are 6 pages, and the index is 17 pages. There are screen displays on many page.

A 64 page Software and Accessories advertising supplement is included, listing about three packages per page. Being the UK version, it isn't exactly immediately of use to Australian readers. The Australian distributor was not listed on any of the material supplied with the model I bought at Harvey Norman. This is really stupid, because the distributor is pretty good, and has an Australian specific advertising supplement readily available. I really wonder sometimes about some of these retailers.

Australian distributor

Vodafone Service Centre

Shops that formerly sold the Psion in Australia include David Jones, Harvey Norman, George's Electronics, WC Penfold, John Maggs, Dymocks, Alders Duty Free, Downtown Duty Free. Check the PsiTech web site for details.

See also Psion 3c

Software Supplied

The Psion includes a nice set of organiser functions running under Psion's own multitasking operating system. It includes a calendar (day, week, and year views), a prioritised to-do list as part of a full agenda utility, a solitaire game, a data base. There is a capable spreadsheet, which includes graphing functions. There is a relatively full word processor, amazingly capable for such a small system. Psion's OPL programming language is included, however you need to obtain the programming manuals as an optional extra. The calculator is rather simplistic, however you can call up OPL proceedures from it (and from most other programs). This entire section needs a rewrite, because the software is the most amazing thing about the Psion.

Please note that the Psion Epoc software described on this site does not work with the earlier Psion SIBO designs. The only page I have relating to Psion SIBO programs is not being maintained nor updated (except when authors send me corrections).

Rumours and Hints

There is a very detailed description of how to convert a 256k Psion to 512k. It covers disassembling, removing the mainboard, the chips needed, and some hints on easiest methods. Check out

The memory chips on the Solid State Disks are reputed to be 4 of 68100 or 128kB chips. The 512kB chips are 684000. These are 32 pin SMD. Reports exist of modifying 128B RAM SSD to make a 2 MB RAM SSD.

I have obtained a detailed description of the 128k to 1 MB SSD upgrade. One (older) type of 128k card can be upgraded to a maximum of 512k by adding 3 extra Intel 28F010 flash memory chips The later model 128k card can be upgraded to 1 MB by using Intel 28F020 chips. Both require resistor changes. The chips are 32 pin PLCC which are pretty fine. If you have any doubts regarding your soldering skills, don't attempt conversion. You will need PLCC desoldering equipment (hot air type). Note that Intel list the 28F020 (256K x 8) and 28F010 (128K x 8) as "first generation flash memory components". This probably means higher density Psion memory cards use a different board. Note that Intel have different model flash memory up to 2 MB x 8. I regret that I no longer know where I found this description. I think it was sent via Usenet around 1997.

Psion are reputed to be a member of a Solid State Floppy-Disk Card Forum involving 57 companies, developing NAND flash memory in a 1/3rd credit card size. Dimensions said to be 0.76mm x 45mm x 37mm, and weigh 1.8 grammes for a 2 MB memory, with hopes of 4 and 8 MB later. See my notes on Compact Flash.

Purple Software have produced a Cyclone Psion Disk Drive, but in very short supply. Designed for mobile use, either battery or mains powered, uses 720k or 1.44 floppy disks, easy to use, and attaches to Psion 3a connector. Comes with a File manager, and you can run software direct from the drive. Purple Software Limited are at Euston House, 81-103 Euston Street, London, NW1 2EZ, phone 0171 387 7777 or fax 0171 387 1188 or email 100526.3715 at There was once a review and photos at

PsiWin 2.3.2 beta needs a Windows bugfix for Psion 3 models. HKEY_CURRENT_USER\SOFTWARE\PSION\TASKSCHEDULER in the field EC_EXTRA change 0 to 36dd

This site will look much better in a browser that supports W3C web standards but it is accessible to any browser or internet device, including Psion Web and similar PDA or limited browsers. Netscape 4.x users - turn Style Sheets off. Your style sheet support is too broken to use (sorry). -> epoc -> epoc hardware -> psion3a

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