Acorn Atom restoration

discussion of games, software, hardware & emulators relating to the Acorn Atom
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Graeme Roberts
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Acorn Atom restoration

Post by Graeme Roberts » Wed Mar 21, 2018 7:30 pm

Hi all,

Just wanted to post an update on my Atom I acquired last week and to ask some questions about some options I want to explore. The machine is a standard Issue 4 with 12K RAM.

First thing I did was to remove the regulators and close links 6 and 7 to make the machine run off a 5 volt regulated supply
IMG_1439.JPG
I then replaced the original DC jack with a more standard 5.5 x 2.1mm one. I noticed that other members were concerned that using a jack like this one off eBay

Image

would cause issues as its height could interfere with the limited amount of space in the slot at the rear of the machine as discussed here viewtopic.php?t=8003.

My solution was to lay it flat on its side and solder connections from it to the board using off cuts from some capacitor legs.
IMG_1440.JPG
This avoids any issues with it being too high and interfering with the Atoms case.
After checking connections I then took the leap of faith and applied power. [-o<
IMG_1443.JPG
So far so good....it's alive. :D

You'll notice that I have quite a few broken key inserts which seems to be the bane of this machine - almost as if Atom users like to smash their keyboards by dropping bricks on them!
IMG_1442.JPG
If anyone has any available either to purchase or swap with some spare Acorn hardware I have, please let me know. Also it would help if anyone has a good method for removing the pegs out of the detached key tops as they appear to be either hot glued or super glued in place. Fortunately all of the keys on this machine work, so it's simply a case of getting the inserts and re-applying the key tops to them.

I've also noticed that the floating point ROM is populated with this chip.
IMG_1441.JPG
The code is MM52132GYR/N. I've googled this part, but I've found very little information about it on line. I assume it's not an FP ROM, as typing P. 3/2 gives the result of 1. :D. I could program an EEPROM with an FP ROM image file, but I'm wondering what chips wold be best to use. Does anyone have any suggestions?

So far I'm pleased with how this has gone and I'm looking forward to continuing with the rebuild. I'd like to add a composite output off pins 9 and 10 of PL4 which shouldn't be too much of a problem. I also have a spare 6522VIA from a VIC20 which I can use to implement the printer port at some stage in the future.

Thanks for reading.
Graeme.

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DutchAcorn
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Re: Acorn Atom restoration

Post by DutchAcorn » Wed Mar 21, 2018 7:57 pm

Thanks for sharing! It is good to see so much love go into this Atom :D
Graeme Roberts wrote:...The code is MM52132GYR/N. I've googled this part, but I've found very little information about it on line. I assume it's not an FP ROM, as typing P. 3/2 gives the result of 1. :D...
Actually, I think you have a genuine, non-masked FP rom. PRINT 3/2 will give you 1 even with a floating point rom installed. Try "FPRINT 3/2" instead.
Paul

Graeme Roberts
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Re: Acorn Atom restoration

Post by Graeme Roberts » Wed Mar 21, 2018 8:07 pm

Thanks for the reply and the hint re: the FPRINT command.
IMG_1444.JPG
That'll teach me to RTFM #-o :D

Graeme.

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CMcDougall
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Re: Acorn Atom restoration

Post by CMcDougall » Wed Mar 21, 2018 8:12 pm

for keyboard on an Issue4, brace yourself.... :(
viewtopic.php?f=44&t=5526&p=51242&hilit ... e+4#p51242
:shock:
ImageImageImage

Graeme Roberts
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Re: Acorn Atom restoration

Post by Graeme Roberts » Wed Mar 21, 2018 8:25 pm

Hi,

Yes, I've read that thread and it does involve a lot of work. :shock: . Fortunately all of the key contacts function correctly so it's electrically complete, I just need the mechanical parts to be able to rebuild it. However I know the key inserts are rarer than hens teeth, and I need eight of them so I can only imagine how difficult it's gong to be to source some. :cry:

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trixster
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Re: Acorn Atom restoration

Post by trixster » Wed Mar 21, 2018 8:38 pm

If you could find a working issue 5 keyboard could you replace the iss4 one with it? Is a 5 a one-for-one swap with a 4?
A3020 | A3000 | A420/1 | BBC B + 128K RAM/ROM + 20K Shadow + Pi0 + VideoNuLA
Master Turbo + DC + BeebSID | Atom | A4000 060 | A3000 060 | A1200 060 | A500
Atari Falcon 060 | Saturn | PS1 | SNES | CPC6128 | C64 | 3DO | MD | Jaguar

crj
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Re: Acorn Atom restoration

Post by crj » Wed Mar 21, 2018 10:10 pm

Nope; looks like it's not. )-8

Compare the photos here with the photos in that other thread of the issue 4 keyboard. It looks as though the older keyboards needed staggered PCB holes - one a little higher than the other, whereas the issue 5 keyboard needs them lined up horizontally.

Graeme Roberts
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Re: Acorn Atom restoration

Post by Graeme Roberts » Wed Mar 21, 2018 10:19 pm

Indeed,

I have a spare BBC keyboard and I was hoping that I could pinch the Futaba switches off that and use them in the Atom. However their pins are in line with each other, while the Issue 4 springs are offset by about 2-3mm from each other, which means if I made the switch the keys would be 'leaning' or offset over to the right :(

Graeme.

crj
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Re: Acorn Atom restoration

Post by crj » Thu Mar 22, 2018 12:35 am

I guess the nuclear option would be a whole new keyboard PCB mounted a few mm above the Atom mainboard.

But then you'd encounter the next problem: finding modern keyswitches the Atom key caps fitted.

(You'd probably also have to live with the keys sticking further out of the casework, which wouldn't be ideal, but sure beats taking a hacksaw to the mainboard of an Atom to make room for a keyboard PCB to lie lower!)

How would people feel about cloning an issue 5 PCB and transplanting all the components from an issue 4? No, thought not.

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danielj
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Re: Acorn Atom restoration

Post by danielj » Thu Mar 22, 2018 6:59 am

What's needed are workable 3d printed plungers...
Don't need to be exact replicas, just "good enough".

d.

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jonb
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Re: Acorn Atom restoration

Post by jonb » Thu Mar 22, 2018 7:56 am

danielj wrote:What's needed are workable 3d printed plungers...
Don't need to be exact replicas, just "good enough".

d.
I thought that, too. It can't be that hard to do, especially for those of us who scored a 3D printer from Aldi. (Not me, sadly!)

Graeme Roberts
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Re: Acorn Atom restoration

Post by Graeme Roberts » Wed Mar 28, 2018 6:39 pm

Hi all,

A quick update to show my composite video modification to the Atom using an RCA connector and a recycled CD Audio connector to make the connection from pins 9 and 10 of PL4 to the outside world.
IMG_1445.JPG
IMG_1446.JPG
IMG_1447.JPG

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