The Psion II range was well ahead of its time when it came to saving data on its machines, however there was an element of strangeness in its design and usability.
You have to realise we are talking early eighties technology and to be totally honest it was the infancy of computing, or hand held computing to be precise. There are three drives on this range of handhelds, they are A:, B: and C:
A: is the internal memory of the unit and it is RAM memory and ranges from 8KB in the CM model, to 16KB in the XP model right through to 32 or 64KB in the LZ/LZ64 models.
B: and C: drives are found on the rear of the unit. Into these slots you can place memory modules that are the equivalent of disk drives you’d find on a computer, however they are pretty much early solid state in design as they have no moving parts. These modules can come in sizes between 8-128Kb in size. B: is always the top slot closer to the screen, C: is the bottom slot closer to the battery compartment.
Types of memory
Rampaks are as it says on the label – Ram based plug in memory modules. When you store something in the units internal memory or on a Rampak, and then you later erase it, it really is erased in its entirety and space on the unit or Rampak is freed up, ready to be used again. Rampaks will have their own small “Coin” type battery as part of the module, this allows the unit to allow the constant input and deletion cycles. They use very little power and are probably the best medium for writing programs.
Datapaks are a different beast. They are known as EPROM (Erasable Programmable read only memory) Erasing a record is comparable to crossing out a piece of work written on paper, it has now been deleted but will always remain on the paper, just crossed out. It’s exactly the same on the Datapak. Hence in time the memory space will dwindle due to the deleted files that remain still occupying dead space. The benefit of the Datapak is that they are more secure and are not affected at all when battery power runs low.
With a Datapak there will come a time when the available memory space remaining is insufficient for what you are trying to achieve. At this point you need to format the drive and this is a particular problem if you don’t have the access to equipment to carry out this task. Here’s why…. They need exposure to Ultraviolet light to erase the memory.
You need one of these, a Datapak, Ultraviolet formatter. Quite a rare beast to be honest, there’s not many on sale at the moment, specific to the Psion. However there are other systems available for EPROMs used in other branches of electronics. The Datapak has to have its label removed to expose the crystal glass below on the EPROM in preparation for being placed inside the formatter. In theory it is just like an oven that exposes the EPROM for around 30 Minutes, the door is closed prior to formatting to keep the light source from damaging the users vision, as the light is in the UV wavelength spectrum likely to cause some quite serious damage or long term conditions.
Here you can see a Datapak that i have taken the lid off of. On the circuit board you can see a piece of crystal glass with a silicon die below, this is the component that will need approx 30 mins of Ultraviolet exposure to format its contents.
The formatting process
Erasure of the EPROM begins to occur with wavelengths shorter than 400nm. Exposure to sunlight for one week or to Fluorescent indoor lighting for three years could cause erasure, this is why the Datapak has a label covering the crystal portion of the EPROM. The recommended procedure is to expose the EPROM to a UV light source at a wavelength at or close to 253.7nm that usually achieves the format process within 20-30 minutes, with the lamp at a distance from the glass lens of around 2.5cm.
Then how do I achieve a format of a Datapak without this equipment?
There was always the option of trying a standard UV bulb or torch. However the UV wavelength on these items for public safety is usually in the 395nm wavelength spectrum. There really is very little available to the general public that is as strong as the bulbs required in the 253nm range to complete this task, as they are a serious danger to health if you are exposed to it for any length of time. This then was not an option i was able to pursue.
I now have a few options available to me if i wish to get these Datapaks formatted.
Purchase a cheap Chinese manufactured unit with a European plug. They seem to work and do the job, however you will be lucky if you get a couple of uses from it.
Trawl EBay. As i write there are two working ones including this MK2 version listed at a reasonable asking price that have a lot of people watching them, so I expect the price to rise accordingly as it gets towards the close of the auction.
EBay spares or repair. There is one unit, a Mk1 version that has a buy now price and it seems to have been hanging about in someone’s junk box for a few years and could possibly need repair. This is a tempting option however if the UV light inside is damaged then i have to look for a suitable replacement, and to be honest there are not a lot of compatible low pressure mercury discharge tubes of these sizes available now. You may have to look for suitable alternatives and I’m not sure i want all that messing around. Do i take the risk and go for one that may need repair? A guy called Dave Curran has combined this drive with one of the Chinese low cost options to create this hybrid eraser: Eprom eraser/upgrade
Get someone else to do it. There is this option and a service is available on line that allows you to send your Datapaks off for someone else to format for you. But do you want to entrust data to a third party? For me it’s not really a problem as none of my units have any of my data on them, but it is something to take into consideration. Whilst I’m searching for a suitable unit this may be a route i consider.
So these are my options. I’ve an idea what I’m going to explore, so im just going to take a little time to look into it all.
My decision
EBay spares and repair – seeing that this is a site where i like to purchase and repair items, i have gone for this option and purchased a used and typically untested Mk1 Psion Datapak formatter from EBay. I have had some good dialogue with the seller and i am confident that this unit can be made good with only a small amount of intervention. The UV tube inside is potentially 40yrs old now, i’ve secured it at a very reasonable price as i got in there and was able to complete the deal relatively quickly.
My plan is to get this unit opened, check its mechanical and electrical stability, get it cleaned, reassembled and then Pat tested. Only then can i look at attempting a full format on it for the first time. And for that i will put together another post incorporating the repair of the unit and the formatting of the Datapak.
Here is my restoration of this unit: Psion datapak formatter
Thanks for passing by.
Foxes Den 
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