PSION Organiser II Forum

Hello fellow Psion Organizer II Users!

My ownership of one of those weird machines started out of the blue.
I saw it on an action and I bought it.
It looked so different that I had to have one.
Fun fact, I am dated the same year as them

Currently I have two LZ64 models with the latest firmware (4.6).
Another one, XP version, is somewhere in the shipping.
Additionally, I've got a couple of datapa(c)ks included: 128k flash, 32k eprom and 32k ramp(c)ak (br2032 battery is obviously dead).

After reading documentation (thanks Jaap) and watching YouTube (thanks Andrew) I started playing with MRAM Datapa(c)k idea and schematic.
I hope I will be able to share with you something (hopefully) interesting (hopefully) soon.

Kind regards,
Michał

PS I misspelled my username - it should be `mb1986` and not `mb1968`, doh

Hello,

I'm very interested if you manage to get the MRam ICs working. Which device(s) are you looking at? They do appear to be a very nice storage solution for datapacks, if a bit heavy on power. The ones I tried were also very expensive at about £40 per IC, but that was during the chip problems a while back.

If the battery in your 32K RAM pack is dead then I'd chop it out, I've seen a few that have been damaged by leakage and then adding a battery holder doesn't work too well.

Andrew

Hi Andrew,

Thanks for your reply!

I've chosen MR0A08B from Everspin (128K x 8 MRAM), datasheet attached.
It draws 70mA max in write mode and 30mA max in read mode, hopefully it will be not to much.
The cost of one of those MRAM ICs is about £14 (in DigiKey).

Please find my current WIP schematic attached

Regarding the battery in my RamPack, yes, you are right I am chopping it out right away, thanks!

Have a great day,
Michał

I had a go with a slightly different device and a slightly different circuit, my circuit attached, be warned, it doesn't appear to work...
I also tried the FRAM devices, that didn't work either.

Cool, thanks for sharing your circuit!
It is always easier having another design to compare things, even if it does not work
I will try to give mine a go, I have to buy ICs, design the PCB, order it... it all takes time unfortunately.

One thing I see at the first glance is that your MRAM chip (the biggest in the family?) takes as twice as much power in comparison to the smaller one which I plan to use (128k x 8).

We'll see, I'll share results when tested.
(I think some kind of a logic analyzer would be useful for debugging.)

Warm welcome!

mb1968 wrote: ↑Sat Apr 20, 2024 6:48 pm PS I misspelled my username - it should be `mb1986` and not `mb1968`, doh

@Martin are you able to change that for Michał?

mb1986 wrote: ↑Mon Apr 22, 2024 3:45 pm Cool, thanks for sharing your circuit!
It is always easier having another design to compare things, even if it does not work
I will try to give mine a go, I have to buy ICs, design the PCB, order it... it all takes time unfortunately.

One thing I see at the first glance is that your MRAM chip (the biggest in the family?) takes as twice as much power in comparison to the smaller one which I plan to use (128k x 8).

We'll see, I'll share results when tested.
(I think some kind of a logic analyzer would be useful for debugging.)

That's interesting about the smaller ICs. I couldn't buy them during the chip problems...

Zenerdiode wrote: ↑Mon Apr 22, 2024 4:38 pm Warm welcome!

mb1968 wrote: ↑Sat Apr 20, 2024 6:48 pm PS I misspelled my username - it should be `mb1986` and not `mb1968`, doh

@Martin are you able to change that for Michał?

Hello and thank you so much, now I feel being myself again