09/02/2019 at 19:57 •
I've worked out how to receive and transmit 3.3V TTL signals directly from/to the Psion Comms Link. This means the Psion can now communicate with 'modern' devices without needing complicated RS232-to-TTL converters and associated dodgy soldering...
Why 3.3V instead of 5V? It turns out that the HC-06 Bluetooth adapter, which I eventually hope to connect to the Comms Link to allow the Organiser & Pi to talk wirelessly, cannot cope with 5V signals on its TX/RX pins. The Comms Link emits 5V TTL signals, so I had to make a simple voltage divider using two resistors, to 'step-down' the 5V signal emitted by the Comms Link to the 3.3V required. It was then a matter of soldering a few wires on to the Comms Link PCB in the right places, found by (vaguely educated!) trial and error. It all seems to work nicely at 1200 baud. For now I've wired it up to the Pi's GPIO TTL pins. In short - The Pi-on is back in action!
The serial cable (which, avid readers will recall, terminates in a bulky DB25 connector) is now surplus to requirements, so I can cut it off to free up space inside the Comms Link's plastic case. Hopefully the Bluetooth adapter will fit inside the case, making the whole thing vaguely elegant...
08/30/2019 at 20:47 •
First - it was lovely to see the Pi-on featured on the Hackaday blog a few weeks ago! (https://hackaday.com/2019/08/03/raspberry-pi-helps-vintage-psion-find-its-voice/)
Since then I've been tinkering about a bit. With the help of the Comms Link I downloaded a word processor to the Organiser. It's called AutoScribe Plus, it was sold by Widget UK (now defunct) in the late eighties/early nineties and it's actually rather good. (Well, it's as good as a 2-line word processor can be!) Widget gave permission back in 2002 for Psion users to distribute their old software freely, so if you have an Organiser II and wish to process words with it, head over to https://www.jaapsch.net/psion/packs.htm, pick 'Autoscribe Plus v5.11' and enjoy.
I even managed to get the Organiser displaying web pages (in pure-text form of course) using the w3m text-mode web browser on the Pi. The Wikipedia home page, BBC News page and the retro Hackaday homepage were all view-able.
Unfortunately some of my soldering surrendered last week, so the Pi-on is now out of action. This led me to think - could I replace the RS232 serial cable connecting the Pi and Psion with a Bluetooth module like this https://tinyurl.com/y5fs4e9q? This transceiver can convert Bluetooth signals to 5V TTL signals and vice versa. The RPi 3 has Bluetooth built in, so it should be possible to wire this chip up to the Comms Link, provided I can find how to supply and receive 5V TTL signals (as opposed to 12V RS232 signals) to/from the Comms Link correctly.
I've dismantled the Comms Link and I've managed to 'insert' a 5-volt TTL signal from an Arduino's serial pins to the Comms Link board, so that the data is received properly on the Organiser screen. Now I need to work out how to 'tap' outgoing 5-volt TTL signals on the Comms Link board before they get converted to RS232 and sent down the serial cable. Here's a hopefully not-too-confusing summary of what I've just attempted to describe!
Injecting 5V TTL data into the Comms Link :
serial cable --> 12V RS232 --> 5V TTL (have managed to 'insert' signals here from an Arduino) --> Organiser
Tapping 5V TTL data before it gets converted by the Comms Link:
Organiser --> 5V TTL (need to 'tap' the signal here) --> 12V RS232 ---> serial cable
07/29/2019 at 20:18 •
The Pi-on Organiser made its first festival appearance yesterday - but hopefully not its last...
...To explain: I am an IOP outreach volunteer, and they kindly allowed me to include '1980s Twitter' as one of the many interesting diversions on offer at the World of Physics at this year's WOMAD festival in Wiltshire. Sunday afternoon punters could type their tweet on the Organiser II then send it via the Comms Link to the Raspberry Pi. The Linux command-line Twitter client 'PTT' and the WOMAD wi-fi did the rest. 64 tweets in total - not exactly 'trending' but still a respectable number. You can browse the tweets @PsionOnline - do give us a retweet or a like (twitter.com/psiononline)
07/26/2019 at 18:43 •
...well, 'elegance' might be overdoing it a bit. With a mixture of skill, cunning and brute force (read: a vague plan and a pair of scissors) I have equipped my Raspberry Pi 3 with a 25-pin serial 'port'. Essentially I removed the old 9-pin female connector from the RS232/TTL converter I was using with a 25-pin male connector. This means that all the fiddling about poking wires into serial connectors is no longer necessary, as I can just plug the Comms Link into the Pi for lovely reliable 1200-baud communication :)
Suffice to say this all relies on some slightly dodgy soldering, but I think it's a great improvement on last week's experimental arrangement. The entire device now fits in the palms of two hands!
The Pi-on Organiser (yes that's what I'm going to call it!) can be used to read RSS feeds, by means of a simple Python script. I can also read mail using mailx, though it is a little difficult.
Assuming my soldering survives, I'm going to be demonstrating the Pi-on Organiser as part of Institute of Physics events this Sunday at the WOMAD festival. (Fits in quite nicely with the 'history of electronics' theme of the day!) I'm setting up Python Twitter Tools - a command-line Twitter client - on my Pi 3 so hopefully punters will be able to write and post tweets from the Organiser II over the Comms Link. Whether anyone will find this remotely interesting (pun not intended) is, of course, yet to be seen...
Update about 2 hours later: Twitter client installed & working! Keep an eye on @PsionOnline this Sunday 28th.
07/18/2019 at 10:51 •
The Comms Link duly arrived on Tuesday, and after a bit of fussing around with serial connectors I have managed to get the Pi and Psion physically connected. Better still, they are actually talking properly to each other at a not-exactly-zippy 1200 baud, using the terminal emulator included with the COMMS software (see previous log). In other words, the Organiser is now acting as a 'dumb' terminal for the Pi. Trouble is, it's not exactly portable at the moment...
In this picture you can see the Organiser with Comms Link attached (bottom right) and the hefty Comms Link cable, which terminates with a female DB25 connector on the left of the photo. My Raspberry Pi 3 (top right) has an RS232/TTL converter attached. The female DB9 connector on this converter is connected to the DB25 connector of the Comms Link by three red wires poked into the relevant holes. This bit is, unsurprisingly, rather fragile. See the table at the bottom.
What can I do so far? I can login to the Pi using the Organiser's keyboard and do all the basic terminal stuff. The only awkward quirk so far (other than the Organiser's tiny 16x2 screen, of course) is that the Psion's EXE key does not act like ENTER. Instead I keep having to press Ctrl-J on the Psion. The left arrow key takes on the role of Control in the Psion COMMS software.
Table of connections...
DB25 on Comms Link - DB9 on RS232/TTL converter TTL side of RS232/TTL converter - Pi GPIO pins Pin 2 - Pin 2 VCC - Pin 1 or Pin 4 (3.3V or 5V) Pin 3 - Pin 3 TXD - Pin 8 Pin 7 - Pin 5 (Ground) RXD - Pin 10 All other pins unconnected GND - Pin 6 (other ground pins are available...)
07/09/2019 at 22:31 •
I've ordered a Comms Link. Well, in fact, it's an original Psion Comms Link with a free Psion Organiser CM included. Yes, that's the right way round - the cable is worth more than the Organiser now! Total cost £22, but I hope to recoup some of that by re-selling the Organiser CM. This is good news for the project, because it means all that fiddling around with machine code and SSCR now won't be necessary. The disadvantage is that the solution won't exactly be compact. Oh well.
What exactly is a Comms Link? It's a device that equips a Psion Organiser II with an RS232 plug. They were sold by Psion as a must-have Organiser accessory for the eyewatering sum of £60 in early 1988 - bear in mind the cheapest Organiser II sold for £99 at that time!
07/03/2019 at 20:49 •
OK, I admit this project hasn't advanced very much recently as I've had quite a lot of other stuff to be getting on with. But I have been trying to make use of the Psion (in its standard form!) in my everyday life. Is it worth buying a Psion Organiser II for a few pounds off eBay in 2019 - if you don't intend to modify it? Well, here are a few uses for the device.
- It's a good, loud alarm clock. You can set 8 alarms up to a week in advance.
- The database is good for storing small amounts of information for short periods of time. I've used it to note down things like phone numbers and brief 'reminder' notes.
- Psion Tetris (see last log) is good fun for whiling away 10 idle minutes.
- You can buy a selection of Datapaks* containing original 1980s Organiser programs on eBay for £7.50 a pop. Things like word processors, the 'Travel Pack' and the 'Games Pack.' I haven't tried any of these but some of them could still be fun and/or useful.
Of course, if (unlike me) you own a fancy smartphone you can do all of these things at lightning speed in glorious Technicolor. But hey, that's what ordinary people do - and being ordinary is a bit of a waste of time.
As a final note - I have noticed recently that some modern (USB) Psion Comms Links have appeared on eBay for the not inconsiderable sum of £35 + postage. Realistically I think the Comms Link route is the only viable way to get the Psion (sort-of) online, so I am tempted to take the plunge. If I do, rest assured I'll witter on about it here...
*'Datapak' was Psion's commercial name for a removable storage device for the Organiser. A Datapak is just an EPROM in a plastic case. It was possible to buy blank datapaks of various sizes (I have a 32K and a 16K Datapak) and also 'pre-recorded' datapaks containing commercial programs. They plug neatly into the back of the Organiser.
06/13/2019 at 19:16 •
The good news: I have managed to physically connect the Pi and Psion. I have also managed to send a simple 'signal' (literally 'pulses' i.e. single bits) from the Psion to the Pi's UART RX pin using SSCR* - but not the other way round. At least, not yet.
It turns out that reading and 'toggling' the pins in the Psion top slot isn't easy! As far as I know there is no simple command in OPL (the Organiser's built-in BASIC-esque high level programming language) that will let me set/read the state of the 3 general-purpose pins in the top slot. It looks like I will need to concoct some simple (?) machine code routines to toggle and read these pins. Until then, I have to stick to Organiser Tetris for my 8-bit entertainment...
Reading data from the Pi using SSCR would only be possible if I get hold of an 'official' Psion Organiser Comms Link, or something hardware compatible with this device. The Comms Link was the commercial name of the RS232-based device Psion produced in the '80s to allow the Organiser to communicate with the PCs of the time - back when PCs had serial ports and monochrome monitors. Psion Comms Links still pop up on eBay from time to time but they aren't cheap. A modern USB version has also been produced and sells for 20 Euros plus postage.
For now, though, I'm going to try and do without a Comms Link. Let's delve into the wonderful world of 1980s machine code...
*pedantic note: the only pin I can toggle with SSCR is pin 2 on the top slot (SD0) which is not the pin I showed in the table in my last post!
06/08/2019 at 20:56 •
So this week I've soldered the low-voltage side of the SparkFun converter board 'onto' the Raspberry Pi. I've let four long leads run freely from the high-voltage side of the board that can be pushed into the pins of the Psion top slot (breadboard-style!)
I've put the connections so far into a table. Now I need to put a fresh Raspbian Lite on the Pi and try to work out how to 'use' the Psion top slot. I believe it has 3 general purpose pins that can be read and written to using some kind of machine code. This page is proving very interesting https://www.jaapsch.net/psion/topslot.htm#p16.
Pi Logic level converter
(low voltage side)
Logic level converter
(high voltage side)
Pin 1 (3.3V) Low Voltage reference
High Voltage reference
Pin 6 (Ground) Ground
Pin 10 (GPIO15) Low Voltage 1
High Voltage 1
Pin 8 (GPIO14) Low Voltage 4
High Voltage 4