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Atomwide A5000 8MB

Posted: Sun Jun 17, 2018 11:58 am
by DutchAcorn
Got this expansion card with an A5000:
47019CC0-C227-43C8-9F73-19115E3FDAAE.jpeg
But it is partly populated and only provides a total of 4MB in this configuration. Google search comes up with Chris’ Acorns; a similar, also partly populated board.

Anyone here seen this board and are fully populated examples seen in the wild?

Re: Atomwide A5000 8MB

Posted: Sun Jun 17, 2018 12:21 pm
by steve3000
I have one identical to that in my A5000 :)

It's provides an additional 2mb to the A5000, bringing it up to 4mb, the extra tracking would provide a further 4mb and dual MEMC sockets - and would plug into the MEMC socket on the A5000's pcb.

From my own investigations a few years back, I was confident in being able to source suitable RAM and MEMCs, but could not find a connecting block to plug into the original MEMC socket, and hadn't begun to investigate the two unknown ICs, which I suspect are probably custom PALs?

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 11:43 am
by RobC
You can get certain types of PLCC plug from RS (search Winslow PLCC - they're not cheap) but I've not been able to find a supplier for this type.

I suspect it should be possible to work out the PLD equations - there's a bit of relevant info here.

I've got a few A5000 8MB expansison but no working A5000 at the moment. They don't look too difficult to replicate.

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 7:09 pm
by DutchAcorn
RobC wrote:
Mon Jun 18, 2018 11:43 am
You can get certain types of PLCC plug from RS (search Winslow PLCC - they're not cheap) but I've not been able to find a supplier for this type.

I suspect it should be possible to work out the PLD equations - there's a bit of relevant info here.

I've got a few A5000 8MB expansison but no working A5000 at the moment. They don't look too difficult to replicate.
Interesting! But I found the memc is not socketed on my A5000 and there are still the two unidentified IC's...

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 8:12 pm
by RobC
DutchAcorn wrote:
Mon Jun 18, 2018 7:09 pm
But I found the memc is not socketed on my A5000 and there are still the two unidentified IC's...
I think it may only be socketed on the later Alpha/33MHz version. I'm pretty sure Steve is right and the unidentified ICs on the Atomwide board are PALs/GALs. So, it'll be a matter of tracing the signals going into them, working out their function and replicating their internal logic.

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 8:32 pm
by DutchAcorn
RobC wrote:
Mon Jun 18, 2018 8:12 pm
I think it may only be socketed on the later Alpha/33MHz version.
The Alpha/33 version was launched in 1993 and this board is from 1991? Odd.

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 8:39 pm
by matt_nottm
Does this help explain?

"Fitting the 4Mb upgrade is a simple task involving no soldering or expert
knowledge. The 4 to 8Mb upgrade however, requires the A5000 to be sent
to Atomwide for fitting. Courier collection & delivery of your machine is
therefore included in the price.

4Mb RAM card - £110.00 (ex. VAT) 4 to 8Mb RAM - £399.00 (ex VAT)"

Acorn User May 1992

Re: Atomwide A5000 8MB

Posted: Mon Jun 18, 2018 10:47 pm
by steve3000
As above, the upgrade needed the original A5000 pcb to be modified. I once owned an original A5000 that had been modified to take a simtech 4-8mb upgrade, the pcb modifications were probably similar to what the Atomwide board needs: the obvious socket fitted for the MEMC, then the two large axial capacitors either side of the MEMC to be moved to the underside of the pcb, and one nearby surface mount capacitor to be removed (later two modifications were to provide space for the upgrade pcb and its stands, so might not be required for the Atomwide board).

Re: Atomwide A5000 8MB

Posted: Tue Jun 19, 2018 5:19 am
by DutchAcorn
matt_nottm wrote:
Mon Jun 18, 2018 8:39 pm
Does this help explain?
Yes it does!

steve3000 wrote:
Mon Jun 18, 2018 10:47 pm
the pcb modifications were probably similar to what the Atomwide board needs: the obvious socket fitted for the MEMC, then the two large axial capacitors either side of the MEMC to be moved to the underside of the pcb, and one nearby surface mount capacitor to be removed (later two modifications were to provide space for the upgrade pcb and its stands, so might not be required for the Atomwide board).
The Atomwide board design leaves enough space for the capacitors but it seems the plug on the memory board needs long pins to reach the memc socket.

5798B627-BB1E-4A2C-9650-908F47271EFC.jpeg
63F4A81E-E6B0-40A1-AD40-C6156773C799.jpeg

Re: Atomwide A5000 8MB

Posted: Wed Jun 27, 2018 8:24 pm
by RobC
Had a look through my A5000 8MB expansions. Two are by Simtec and the other is by Atomwide but not the one shown in this thread.

However, it does have two GALs fitted - it's possible that they are similar to those intended for this card.

Re: Atomwide A5000 8MB

Posted: Wed Jun 27, 2018 9:04 pm
by lcww1
I think that the 8Mb RAM card in one of my A5000s is a fully populated version of the Atomwide card shown in the picture at the beginning of this thread. I’ll need to dig out the machine from under the rubble of electronics clobber on my desk and take a picture. It would be marvellous to clone this RAM board, so that A5000s could be more readily upgraded.

Re: Atomwide A5000 8MB

Posted: Sat Sep 15, 2018 1:39 pm
by lcww1
Well, it’s taken me a little while to dig out and open up my A5000 with the Atomwide 8Mb RAM expansion card, but here are a couple of photos - it’s a fully populated version of DutchAcorn’s board. As the photos show, U4 and U5 aren’t GALs but PEEL PLDs - datasheet here: https://datasheet.octopart.com/18CV8P-2 ... 276731.pdf


86DDA9D5-6D97-4843-9477-E400EE0CD30C.jpeg
Atomwide A5000 8Mb RAM V1.1
69028156-90B4-432B-B175-F485BADE0ABC.jpeg
Atomwide A5000 8Mb RAM V1.1 - U4 and U5 PEELs

I suppose it will be possible to read these PEELs? Not something I’ve done before...

Re: Atomwide A5000 8MB

Posted: Sat Sep 15, 2018 3:04 pm
by lcww1
I see from the “Design Security“ section on p4 of the datasheet that these PEEL devices have a security bit that may be set at the time of programming to prevent subsequent “unauthorized reading or copying of designs programmed into the device”. Furthermore, it appears that relatively few programmers can handle these devices - it seems that the common TL866 can’t handle these devices - the Chipmax2 can, though it’s somewhat pricey https://www.mouser.co.uk/ProductDetail/ ... gLQoLWtQ==. If there’s someone on the forum with a suitable programmer, then I’d be willing to send he/she the PEELs from my Atomwide RAM board for investigation (they’re socketed, as the photos show) - unless we try to read them we’ll not know whether they’re protected or not ...

Re: Atomwide A5000 8MB

Posted: Sun Sep 16, 2018 7:19 am
by daveejhitchins
Both my programmers list these parts. I won't be in a position to assist until October, however. So if someone else pops-up before then . . .

Let me know - Dave H :D

Re: Atomwide A5000 8MB

Posted: Wed Sep 19, 2018 10:14 pm
by lcww1
Thanks for the kind offer Dave!
I’ll take you up on that, if I may?
There’s no hurry from my point of view, so I’ll just post the chips to you next month, if that’s ok with you.

Re: Atomwide A5000 8MB

Posted: Thu Sep 20, 2018 5:37 pm
by daveejhitchins
lcww1 wrote:
Wed Sep 19, 2018 10:14 pm
Thanks for the kind offer Dave!
I’ll take you up on that, if I may?
There’s no hurry from my point of view, so I’ll just post the chips to you next month, if that’s ok with you.
I'll PM you my address . . .

Dave H :D

Re: Atomwide A5000 8MB

Posted: Wed Sep 26, 2018 1:09 am
by AndyMc1280
RobC wrote:
Mon Jun 18, 2018 11:43 am
I've got a few A5000 8MB expansison but no working A5000 at the moment. They don't look too difficult to replicate.
Butting in, slightly related I have an atomwide 8mb Upgrade from my previous dead A5000... However nooblet me when removing it from said previous A5000, was a little too 'robust', and as a result tore one end of the ribbon cable (the one with the jaggy connector) As well as bleeding all over the floor and cursing, this thoroughly narked me to the point of being rather fed upwith A5000's in general.

My soldering expert friend put a new socket and ribbon cable on it a while back but being unable to test, as I no longer had the A5000, the upgrade sat in a drawer for a year until now.

Today, I took delivery of another friend's A5000 Alpha. I'm keeping this one, but we fitted the 8 Mb board and the machine works, but only shows 4MB.

This could be any one of the following:

A Memc Chip Died when the old A5000 failed. I never took the chips out - just removed the riser board with both Memc1A still in place. I took the working memc that came in the alpha out and put the populated dual socket board in.

I forgot that the cable basically folds at a 90 angle so it is plugged in the wrong way round.

The new sharp socket isnt working.

Some of the logic on the upgrade failed when the old machine died.

How the heck can I diagnose this ? (Dont really feel like Giving CJE £140)

Re: Atomwide A5000 8MB

Posted: Wed Sep 26, 2018 6:26 am
by steve3000
Dead (or not) MEMC should be easy to test if you have a chip extractor tool and A5000a with MEMC socket... that said, they can be a pain to remove unless the tool is fully engaged. I'd test these first as the logic is going to be tougher to test.

Re: Atomwide A5000 8MB

Posted: Wed Sep 26, 2018 10:52 am
by hubersn
AndyMc1280 wrote:
Wed Sep 26, 2018 1:09 am
Today, I took delivery of another friend's A5000 Alpha. I'm keeping this one, but we fitted the 8 Mb board and the machine works, but only shows 4MB.
The Alpha variant of the A5000 had, IIRC, a 16 MHz system bus (and hence memory) clock. It needed "special" MEMC1a that worked at that speed, and I think I remember a lot of discussions about "matched" MEMC1a to get it working reliably.

On the other hand, Chris' Acorn tells me that the Alpha variant also had 12 MHz memory clock...

Have fun
hubersn

Re: Atomwide A5000 8MB

Posted: Wed Sep 26, 2018 10:54 pm
by steve3000
hubersn wrote:
Wed Sep 26, 2018 10:52 am
The Alpha variant of the A5000 had, IIRC, a 16 MHz system bus (and hence memory) clock. It needed "special" MEMC1a that worked at that speed, and I think I remember a lot of discussions about "matched" MEMC1a to get it working reliably.

On the other hand, Chris' Acorn tells me that the Alpha variant also had 12 MHz memory clock...
Interesting! I didn't think the memory ran any faster in the alpha, must investigate...!Si can time the RAM speed IIRC, I'll load it up next time my alpha is running...either way, I plugged a 'standard' dual memc 8mb upgrade from my original A5000 into my alpha with no problem, (although could be luck!).

Re: Atomwide A5000 8MB

Posted: Thu Sep 27, 2018 7:40 am
by RobC
hubersn wrote:
Wed Sep 26, 2018 10:52 am
On the other hand, Chris' Acorn tells me that the Alpha variant also had 12 MHz memory clock...
My Alpha has a 12MHz memory clock and 12MHz-rated MEMC1A and is the same as the stock A540.

I overclocked my A540's memory to run at 16MHz by replacing all the zip rams with 60nS parts (still using 12MHz MEMCs). Any faster and I got I/O issues though.