Retrocomputing – getting re-acquainted with the Psion Series 3a and MC400

Back in the 1990s I was a serious Psion addict. I bought the first Series3 as soon as it came out in 1991 and was immediately hooked. Although it was tiny it was the first proper computer I’d owned. The Series 3a was released in 1993 and I upgraded first to a 512k model, then to the 2M model in 1995 – after that I also owned Siena, Series5 and Revo models. But as I look back on those times some 26 years later, for me the 3a 2M was “Peak Psion” – it was just in the sweet spot, somehow it was better than the later models even though they were technically superior (apparently Science Fiction writer Charles Stross agrees) 😀 Something about the form factor, the depth of functionality of the built-in apps and the expandability that the programming language OPL allows was just right. And it would run for ~40 hours on a couple of AAs! The development of the 16-bit SIBO range effectively stopped as the 32-bit models with EPOC32 were released & took priority – who knows what might have happened if the platform was actively developed?

Reading the history of the development of the MC & Series 3 machines in David Wood‘s excellent book “Smartphones and beyond” gives an insight into the fanatical engineering employed to create such functionality with sparse resources – the Series 3/3a’s processor was 16-bit 8086 based and with only 1M of ROM. Object oriented development, sharing code in libraries and copious use of assembly language all helped to shoehorn an impressive feature list into a tiny space. This endears the Psion to me even more. One of the memorable anecdotes I’ve read is that the entire word processing app in ROM occupies less space than a blank MS Word document.

After recently rediscovering my MC400 software I’d written in 1995 it re-ignited my passion for these Psion machines and after looking on eBay I just couldn’t resist. After 20-odd years without a Psion machine in the house all of a sudden I’m now the owner of 2 – an MC400 Word and a Series 3a 2M.

The MC400 has had a tough life – the previous owner had stored (and probably forgotten about) it in his shed and the rechargeable NiCad battery pack had leaked and corroded some of the machine’s internals. No worry – I’ll strip it down and give it some TLC. The machine arrived with the plastic case of the dead NiCad battery in place but someone has hacked out the actual cells. Also there’s a column about half the screen height of a few pixels wide that are dead.

Poor rechargeable battery pack hacked to bits by previous owner

The MC was also bounced around by the courier, not helped by the seller wrapping it in only one layer of the thinnest bubble-wrap, and it arrived with several of its keycaps dislodged.

The Series 3a seems to be in reasonable condition – a few of the keys feel like they don’t travel as far as they should, maybe there’s debris under them and the LCD has some slight variation in tone but overall it’s not too bad for a machine that’s 26 years old! I must’ve jinxed it – just after writing the above line the post that sits between the 2 AA batteries has just snapped off… but apart from that so far it’s holding together…

Transferring files via dosbox (on Linux) and mclink.exe

My new series 3a was sold with the 3Link “soap on a rope” serial link and the other half of it (9-pin mini-DIN to 9/25way D-type) also works with the MC.

I’ve got plans to write some OPL to get both of these machines controlling my Technics cassette deck – it’ll be a real 1990s tech-fest 😀 I’ve got a NodeMCU board set-up to emulate a modem and I’ll be re-writing some of the code on the Raspberry Pi that controls the tape deck to be able to handle the serial output from the Psions…. see here.

Technics RS-B665 cassette deck remote control via OPL and serial cable…
NodeMCU lined up for duty connecting the MC400 to “the internet”
backlight not required 🙂
connecting to the outside world via a Raspberry Pi (what else? 😀 )
Swapping SSDs to convert screenshots…

Psion series 3a disassemble
backing up files like it’s 1997! At 19200 baud 🙂

Published by zedstarr

Chilled out human being, doing techy stuff.

5 thoughts on “Retrocomputing – getting re-acquainted with the Psion Series 3a and MC400

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