Psion PDAs (was Re: Modern replica/implementation of a dumb terminal?)

From: Andreas Freiherr <>
Date: Thu Dec 5 06:55:12 2002


yes, it is truly a matter of personal preferences:

>>you're talking in the past? - I am still using my Psion 3mx every day,
> For me I am ;) I don't doubt that you still find your Psion 3 useful. If
> I didn't have my Series 5 I would still be using my 3a.

I forwarded my Series 5 to my brother, who is happy with it, while I
happily continue to use the 3mx.

> Huh? What is V-Tel? Sounds *very* interesting. The "3a Box" program was

I mentioned V-Tel in one of my earlier postings on cctech, and promptly
got a request for it off-list. It is a combined VT320 emulator and
Telnet utility, so you can use the 3a/c/mx for dialling into a TCP/IP
network and establish sessions to all kinds of hosts, with the ability
to use screen-oriented applications: editors, monitoring tools, games,
... ;-)

Before I started to write V-Tel, I looked for an existing application,
but found only a very elementary Telnet program (from Simon Wood; in the
comment lines, it said it was there only to prove that it is possible)
and a number of VT emulators, but none of them was able to connect
through the TCP/IP stack: they all used the serial interface
exclusively. Then I dug out an original VT320 (for comparison) and a
couple of manuals, downloaded RFC854...

> Sadly, I believe the source is now lost for good. The harddrive that had
> the backup files for that Psion has long since crashed and the batteries
> (main and backup) on my 3a went dead and took the program with it :(

A SSD (solid state disk) might have helped. I have two of the 4MB
devices in the A and B slots of my 3mx, but currently only need one of
them to store data. So, with my internal RAM (2MB) and a total of 10MB,
I am excellently equipped: for comparison, a spreadsheet including two
different graphical representations and a listing of daily stock rates
for three different papers over the course of a year takes about 50kB on
the 3mx. This includes the formulas to calculate values for sample
accounts (one account per paper) for each day.

> * Actually, in the movie Executive Decision with Steven Seagal (the only
> one he's in where his character dies) and Kurt Russell, the terrorist on
> the plane is using a Psion 3a as the remote bomb control :)

I vaguely remembered having seen such a scene. That's where it was? -
Thanks for the pointer! (However, I prefer other applications!)

>>Too bad that the infrared interface (3c, 3mx) was built too early to
>>conform to all relevant IRDC standards, but if I can locate some
>>information from the Psion SDK, there might be a solution...
> Is it compatible with the Series 5 at least? Probably not as I imagine
> the Series 5 conforms to standard.

The infrared port of my 3mx does not work with my Nokia 6210, so I have
to carry around both serial cables and a null modem. Well, actually a
"null terminal" adapter (two male connectors) because both cables are
designed to connect to a PC (= to a DTE). This adaptor was much easier
to build than to find in a shop.

Going infrared, the Psion "sees" the cell phone in the proximity, and
with a small OPL program (OPL again!), you can prove that it can contact
the device and retrieve a description string, but you cannot access the
modem in the 6210. This is why I assume an incompatibility on a somewhat
higher layer of the IRDC protocol stack.

I seem to remember having seen programs for the 3 and 5 to allow the
exchange of data between these machines. Apparently, these programs
simply implement higher protocol levels themselves.

>>As for the RS232 interface, the "soap on rope" cable used with the 3/3a
>>was changed into something that looks like a simple cable for the later
>>models (3c/3mx), I think it might be the same type as for the Series 5,
>>with a small flat connector at the PDA end instead of the 3-by-2
>>Berg-style plug.
> But I thought the dongle had the actual serial hardware in it, whereas on
> the Series 5 it is built-in?

Right. Also built-in with 3c and 3mx. The 3 and 3a had a proprietary
(IIRC, 1.5Mb/s, full duplex) link between the Psion and the dongle. This
is why the same 6-pin connector could also be used for a parallel
printer interface.

>>absolutely personal opinion, of course. I tried a Series 5, but compared
>>to the Series 3, it didn't do enough to justify the switch: not even the
>>Opera browser could do what I was looking for, so I gave up and kept the
> I didn't realize that was Opera! Cool.

Opera was not the original Web browser from Psion, but you could
download and install an EPOC version of Opera from their Web site.
Unfortunately, both browsers refused "https:", so I still have to boot
the PC for home banking. No "mobile banking" yet ;-)

> One of these days I'm going to get Linux installed on my spare (if I can
> fix it) just to do it.

Should I ever need another PDA, it may well be Linux-based, especially
if it can do ssh instead of Telnet and IPsec with TCP/IP. I keep my
fingers crossed for your fixing the device and installing the O/S!

Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
Received on Thu Dec 05 2002 - 06:55:12 GMT

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