256K RAM Pack

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amenjet
Posts: 179
Joined: Tue Jan 03, 2023 7:54 pm

256K RAM Pack

Post by amenjet »

Well, after a lot of investigation, and some new commands for the datapack tool, and quite a long session using the 'debug finger', I think I have tracked down the problem with my 256K RAM pack. After studying the design and comparing it against other designs I was convinced there wasn't anything wrong with it, and indeed that was the case. Two pins weren't soldered causing odd data values on read and probably write. I soldered those pins and it's been fine ever since. I now need to fit a battery in the case somehow, and that might require either a smaller battery or a smaller RAM chip. the circuit should be good for capacities up to 1Mb, as well.
So, still a way to go, but a major hurdle overcome.

Andrew
MartinP
Posts: 45
Joined: Wed Jan 04, 2023 7:51 pm

Re: 256K RAM Pack

Post by MartinP »

That's great news! Glad there was nothing much wrong with it. Tricky fault to find 'though.
Martin P.
amenjet
Posts: 179
Joined: Tue Jan 03, 2023 7:54 pm

Re: 256K RAM Pack

Post by amenjet »

MartinP wrote: Thu Apr 20, 2023 7:15 pm That's great news! Glad there was nothing much wrong with it. Tricky fault to find 'though.
Martin P.
Yes, I had to use the 'magic finger' and some datapak tool code, which is now in the repo. Unfortunately I have found that the battery drain is high and at the moment the obvious fix stops the pak from working, so more to look at.

Andrew
MartinP
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Joined: Wed Jan 04, 2023 7:51 pm

Re: 256K RAM Pack

Post by MartinP »

Hmm, do you have a 'magic finger' because you are a wizard? Or is there a less magical explanation?
Martin P.
amenjet
Posts: 179
Joined: Tue Jan 03, 2023 7:54 pm

Re: 256K RAM Pack

Post by amenjet »

MartinP wrote: Fri Apr 21, 2023 5:45 pm Hmm, do you have a 'magic finger' because you are a wizard? Or is there a less magical explanation?
Martin P.
No, I have a magic finger because it has capacitance...
I'll do a video about it some time. It's a useful technique for finding some sorts of problems, usually open circuits, unsoldered pins etc.

Andrew
PaulK
Posts: 43
Joined: Wed Jan 04, 2023 11:54 am

Re: 256K RAM Pack

Post by PaulK »

This is sounding very promising!

The thought of a 1mb RAM pack is exciting indeed.

Thanks for your wizardry Andrew!

All the best
Paul
amenjet
Posts: 179
Joined: Tue Jan 03, 2023 7:54 pm

Re: 256K RAM Pack

Post by amenjet »

PaulK wrote: Mon Apr 24, 2023 1:46 pm This is sounding very promising!

The thought of a 1mb RAM pack is exciting indeed.

Thanks for your wizardry Andrew!

All the best
Paul
If I can find a chip that is that big and an get the final bugs ironed out then I might try it. It'll take a while to size though...
i think the theoretical maximum size of a datapack is 2Mbytes. You could maybe do some bank switching but it would have to be hidden from the organiser code.

Andrew
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Martin
Global Admin
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Joined: Mon Jan 02, 2023 5:18 pm

Large capacity packs

Post by Martin »

Hi Chaps

Experience suggests than anything bigger than 512K becomes hard to use/manage. Without the facility to create subdirectories the Dir list of a large capacity pack becomes unwieldy and time consuming, especially on a CM/XP with its lack of file handling functions.

Although if anyone has suggested back in the day that we would be discussing the possibility of a 1MB pack we would have checked it wasn't April 1st.

Sincerely and in good faith
Martin
amenjet
Posts: 179
Joined: Tue Jan 03, 2023 7:54 pm

Re: Large capacity packs

Post by amenjet »

Martin wrote: Mon Apr 24, 2023 9:12 pm Hi Chaps

Experience suggests than anything bigger than 512K becomes hard to use/manage. Without the facility to create subdirectories the Dir list of a large capacity pack becomes unwieldy and time consuming, especially on a CM/XP with its lack of file handling functions.

Although if anyone has suggested back in the day that we would be discussing the possibility of a 1MB pack we would have checked it wasn't April 1st.

Sincerely and in good faith
Martin
Yes,i agree. The RAM packs are fast though, so a 1Mbyte or 2Mbyte pack might just be workable. I am using a 512K flash pack and that is OK as things remain in the pack when deleted so having the extra space is useful. They are also non0-volatile technology and seem robust so security of data is better, I think. I back up over USB and copy data to another pack when one is getting full. You do need two flash packs, really, so you have one to copy data to (a ram pack would do, I suppose), and a pack that has the flash formatting code on it.

Andrew
thesourcerer
Posts: 55
Joined: Sat Jan 07, 2023 1:00 pm

Re: 256K RAM Pack

Post by thesourcerer »

There were large Rampacks produced for the Psion II’s. I sold a 512k to Jaap (which is on his site) and I remember seeing 1Mb (and I think 2Mb?) on a Widget software price list, however they were in a piggyback format, which meant that the second datapack could not be changed when they were in situ. Unsurprisingly they are very rare, due to the price in the early 90’s (over £250 and over £500 respectively). I’ve not physically seen either, but I did have 3 of the 512k Rampacks which I sold for £100 each.
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