Acorn 3000 4mb Ram Expansion

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BradBrad
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Acorn 3000 4mb Ram Expansion

Postby BradBrad » Fri Sep 15, 2017 3:36 pm

Hi All,

My A3000 currently has a 2mb ram module in it. The machine posts as 2mb so not sure if there is on onboard ram in addition to the module or not :shock:

Anyway, I am looking to upgrade it to 4mb (mostly so I can run ADFFS)

I can't find anything on Ebay. Does anyone know if it would be easy / possible to 'roll my own' using toner transfer method etc? I have done a couple of one sided boards to date and have a few tools.

Is there a schematic/pcb layout and bill of materials available anywhere? Maybe even an Eagle file or something that could be printed out for pcb etching?

Thanks.
Last edited by 1024MAK on Fri Sep 15, 2017 6:19 pm, edited 1 time in total.
Reason: Corrected typo

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Fri Sep 15, 2017 3:39 pm

Sorry, it is an ACORN A3000. The keyboard on my phone sucks :lol:

RobC
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Re: Acorn 3000 4mb Ram Expansion

Postby RobC » Fri Sep 15, 2017 6:30 pm

Dave Hitchins had some 4MB boards a while back so it might be worth contacting him.

philb
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Re: Acorn 3000 4mb Ram Expansion

Postby philb » Fri Sep 15, 2017 7:08 pm

BradBrad wrote:My A3000 currently has a 2mb ram module in it. The machine posts as 2mb so not sure if there is on onboard ram in addition to the module or not :shock:


Yes, there is 1MB on the baseboard and another 1MB on the expansion card.

I can't find anything on Ebay. Does anyone know if it would be easy / possible to 'roll my own' using toner transfer method etc? I have done a couple of one sided boards to date and have a few tools.

Is there a schematic/pcb layout and bill of materials available anywhere? Maybe even an Eagle file or something that could be printed out for pcb etching?


I think the schematics, and possibly even the PCB artworks, might be in the technical reference manual which you can find online. I'm not sure you could do it as a single sided board though, it would probably need to be PTH. Other than that I don't think there is anything terribly difficult, and I have occasionally been tempted to make one up for my own A3000 which also has only 2MB. But then I always get sidetracked into thinking that if I was going to design a PCB then it ought really to have 16MB on, which of course makes it a whole other thing.

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Sat Sep 16, 2017 7:31 am

RobC wrote:Dave Hitchins had some 4MB boards a while back so it might be worth contacting him.
Yes, still have those. The board is free, as they were supplied by Steve Picton =D> The RAM (TC514400AZ-60) will £1.40 each - 8 x needed = £11.20 + P&P. - However, as they haven't been tested, there may be some drop-out! So, I'd supply double the amount with any not being used returned.

PM if anyone is interested . . .

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Sat Sep 16, 2017 11:14 am

Hi Dave, I am very interested. How would I arrange? Paypal? Can't PM yet as too new :lol: I tried sending an email too. Thanks.

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Sat Sep 16, 2017 3:58 pm

BradBrad wrote:Hi Dave, I am very interested. How would I arrange? Paypal? Can't PM yet as too new :lol: I tried sending an email too. Thanks.
Brad . . . Received your mail, thanks.

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Sun Sep 17, 2017 8:30 pm

PM if anyone is interested . . .


Hi Dave, I'm also interested but also unable to PM you. Could you perhaps PM me if you have any 4MB boards left?

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Sun Sep 17, 2017 9:29 pm

Mark, PM sent . . .

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Tue Sep 19, 2017 2:29 pm

Good show Dave =D> =D> =D>

The RAM arrived this morning and the first one opened posts as 4096K :)

Going to let it run a bit...

Please let me know where to send the second board back to.

I have also swapped out the dodgy Conner drive for another (probably equally dodgy :lol: ) Conner drive which came from an Amiga 600.

I am also going for it with the Gotek floppy emulator drive....

Does anybody know which is pin 1 on the motherboard floppy header? There are no markings and the tab hole seems to be reversed :shock: Don't want to screw it up now.

Cheers.
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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Tue Sep 19, 2017 4:33 pm

BradBrad wrote:Please let me know where to send the second board back to.
I enclosed a return address label!

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Tue Sep 19, 2017 8:11 pm

Cool. Yeah. I just found it. Will post tomorrow morning.

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Wed Sep 20, 2017 7:11 am

Mark's ^^^ RAM didn't work! Are there any links to change?

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

RobC
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Re: Acorn 3000 4mb Ram Expansion

Postby RobC » Wed Sep 20, 2017 7:40 am

daveejhitchins wrote:Are there any links to change?

From memory, I don't believe so.

However, there are sometimes links on the board to differentiate between 1M and 4M versions.

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Wed Sep 20, 2017 7:46 am

RobC wrote:
daveejhitchins wrote:Are there any links to change?

From memory, I don't believe so.

However, there are sometimes links on the board to differentiate between 1M and 4M versions.
Wouldn't indicate there would be something to change?? Or are they 'passive' model identification?

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

RobC
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Re: Acorn 3000 4mb Ram Expansion

Postby RobC » Wed Sep 20, 2017 8:03 am

daveejhitchins wrote:Wouldn't indicate there would be something to change?? Or are they 'passive' model identification?

I made some notes on this when I was upgrading my 1MB board to 4MB. The bank signal is tied high on the board for 1MB (2MB in total) but connected to A9 (again on the board) for 4MB. I guess the OS then works out how much memory is present on boot.

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Wed Sep 20, 2017 8:25 am

That's a shame . . . I've just checked the service manual. It details a 1Mb to 2Mb upgrade only!

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Wed Sep 20, 2017 1:03 pm

There is a jumper on the ram board. 2 or 4MB. I left it at 4. Everything else on the mainboard was just left as it was. The machine did have a 2mb board in it before so maybe that helped.

Anyway, I just posted the other board back so you should have it tomorrow or Friday. First Class, Signed for.

Thanks again Dave. =D>

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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Wed Sep 20, 2017 1:09 pm

Let me know if you want pics of any jumpers and I will post them. I have to open it up in a day or so again as the Gotek floppy mod was de-railed for a bit due to ........
.....
... a bad floppy cable :lol:

The Gotek drive itself fits sweetly though and looks the business. No changes to the case needed, of course [-X

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daveejhitchins
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Re: Acorn 3000 4mb Ram Expansion

Postby daveejhitchins » Wed Sep 20, 2017 7:52 pm

BradBrad wrote:Let me know if you want pics of any jumpers and I will post them.
Yes, please . . . I'll need to see if we can Mark's A3000 to accept the upgrade.

Dave H :d
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Wed Sep 20, 2017 8:48 pm

I originally tried to fit the 4MB ram boards last night without any success. The computer wouldn't boot with either board fitted. I got a red screen and a flashing floppy disk light. I did not note down the error code.

The computer booted fine when I removed the RAM expansion entirely and also when I re-inserted my existing 2MB RAM expansion board.

I tried both of the boards again this evening and was still unable to get them to work. I also tried changing the jumpers on the boards from 4MB to 2MB but it didn't make any difference. In fact on one of the boards it made things worse. I didn't even get the flashing floppy disk lights any more. Just a blue screen. I took more notice of the flashing lights on the floppy disk this evening with the jumpers set to 2MB. My impression is that the first error code reported was "RAM control line failure", but as I didn't actually note the flashes down on paper, I can't be absolutely sure. Again, the machine booted up fine when my old 2MB RAM board was inserted.

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Fri Sep 22, 2017 1:42 am

Ok. I'll open her up tomorrow and take a few pics.

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Fri Sep 22, 2017 4:04 pm

Here are pics of all the links I can see. In addition, the jumper on the ram board is set to 4mb. Good luck.

I am still having a nightmare with the Gotek drive on the Arch but a £14, issue 2 Electron off EBay turned up yesterday and is going fine. Heatsink on the ULA and a retrobrite and it will be golden :D
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markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Fri Sep 22, 2017 6:48 pm

I checked the jumpers in my A3000. The only difference I can see between our two jumper configurations is LK25, which according to the service manaual is used to configure the RGB Video Socket, so I guess this is unlikely to be the issue. If I read the manual correctly, your A3000 is configured as 'VSync' whereas mine is configured as 'Mode'.

Thanks very much for taking the time to post the pictures.

BradBrad
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Re: Acorn 3000 4mb Ram Expansion

Postby BradBrad » Fri Sep 22, 2017 7:20 pm

markdryan wrote: your A3000 is configured as 'VSync' whereas mine is configured as 'Mode'.


Lol, I haven't dared touch any jumpers, that may help explain my scart picture being shoved to the right :lol:


Happy to help mate. I couldn't see any more jumpers but if you know of any others then I can have a look.

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1024MAK
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Re: Acorn 3000 4mb Ram Expansion

Postby 1024MAK » Fri Sep 22, 2017 8:14 pm

@ Mark - I presume you have checked all the pin connections for the RAM connector including the solder joints? Both on the main board and on the RAM board. If not, it would be a good idea just in case there is dirt, corrosion or a dry solder joint :idea:

Mark
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paulv
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Re: Acorn 3000 4mb Ram Expansion

Postby paulv » Fri Sep 22, 2017 9:00 pm

ISTR there are some 4MB RAM expansions for the A3000 that require a small flying lead to connect to a pin on IC28 or 29. Most boards don't require it but some do. I've certainly got one A3000 with such a lead...

You can just make out the BROWN flying lead in the bottom left of the photo on the link below:

http://www.retro-kit.co.uk/page.cfm/content/IFEL-3MB-RAM-upgrade/

Paul

markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Fri Sep 22, 2017 9:09 pm

I presume you have checked all the pin connections for the RAM connector including the solder joints?


Actually, I haven't. However, I do have an existing 1MB expansion board fitted that works fine, i.e., the A3000 boots and reports 2MBs. So I guess that means that the main board is okay, unless of course the 1MB expansion board doesn't use all the pins. Is it still worth testing the main board? If so, how would I do this?

The 1MB board is screwed into the motherboard whereas neither of the 3MB boards are. The 3MB boards seem to sit closer to the motherboard when fitted and are looser. Not sure if this is significant.
Last edited by markdryan on Fri Sep 22, 2017 9:19 pm, edited 1 time in total.

markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Fri Sep 22, 2017 9:18 pm

The 3MB boards are both Atomiwide boards, one dated 1992 and the other 1990. I guess like this one

http://chrisacorns.computinghistory.org ... MBRAM.html

The boards are different. The 2MB/4Mb jumpers are in different positions on the two boards. In the 1992 version the 4Mb setting is at the top.

markdryan
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Re: Acorn 3000 4mb Ram Expansion

Postby markdryan » Fri Sep 22, 2017 9:43 pm

Is it still worth testing the main board? If so, how would I do this?


Okay, I think I see how to do this. I'll have a go tomorrow. Thanks for the suggestion.


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