New (to me) Atom

[tomkinsg]

I have acquired an Atom - a rescue from ebay. I spent the last few days cleaning it and i now need to think about getting it fired up. The keyboard is clean, IPA on the motherboard has certainly made it a bit more sparkly and also I did brighten the case a little with some hydrogen peroxide and mother nature's help - its now a little less yellowed. Its looking good.

now I need to try to get it going and I know there are a lot of good people here that I am hoping will help me.

First, I need a power supply. There was a red wire and a black wire hanging out the back of the atom originally and LK6 and LK7 were linked. So i assume those wires were to connect to a 5V PSU. I took the wires off and cleaned up LK6 and LK7 because they were ugly and replaced them with aim of using a 5V 3A PSU. I can find 5v 3a power supplies but not with a 5mm barrel plug. I can only find 5.5mm. I tried a 5.5mm plug i have here and sure enough it wont fit. But you know that already

Any links to any suitable PSUs out there would be gratefully received - I should add, I am in the US!

Alternatively, i assume it should not be hard to pull out the old 5mm barrel socket out and replace with a new 5.5mm barrel socket. Again any links to some sample parts would be good and i can try source one out here in the US.

My board is fully populated except for the 6522 VIA in IC1. I believe it is not critical it be there but I have one that i can slot in out of my original series 3 BBC micro board if needed.

Is there a list of all the links on the motherboard? some seem to have been added and i am not sure that is a good or a bad thing.

LK1 open
LK2 closed
LK3 open
LK4 erm - didn't find a LK4 on visual inspection
LK5 open
LK6 closed - this is know is 5V regulated PSU
LK7 closed - this is know is 5V regulated PSU

I am also in need to get this hooked up to a monitor. I plan to use a RGBtoHDMI that i have for my model B. the wiki (https://github.com/hoglet67/RGBtoHDMI/w ... -Computers) for it says its compatible with Acorn Atom TTL - am i right that is using the video connector PL4? I have the schematic from the same wiki of how to wire it and some parts on order.

There is a mod on this - a wire running from pin2 or pin 6 of the cassette connector to one of the pins on PL5, the VIA PRINTER I/O port. Any ideas on what this is for?

Does the Atom make a beep thru its speaker on power up? That would be useful to know!!


Finally, for now at least, I have two EPROMs in IC21 and IC24. I will take them out to see if I can read off them. They had no cover over their glass until now, so no idea of their condition. Not sure what should be in them. I have just found a hardware guide so I will look into that too.


Finally finally, There are a lot of 2114 memory chips and I expect there's going to be one or two with issues. Is there a good troubleshooting reference that guides me through the symptoms and where to start looking?


thanks
Glyn

[jms2]

Hi Glyn,

I was in a similar position to you recently and posted about it on here. I have two observations which I think will be helpful.

1. Farnell in the US (but only in the US) sell a 5mm power plug that should fit the Atom. It is part number 27-1125. There's a £16 charge to import these to the UK!

2. Of the 2114s, the lower two which are aligned horizontally are critical as they contain page zero. Try removing and swapping with other positions. I found all my ram was actually ok once removed and put back.

[roland]

I have acquired an Atom - a rescue from ebay.

Congratulations I'll try to answer a few questions for you.

My board is fully populated except for the 6522 VIA in IC1. I believe it is not critical it be there but I have one that i can slot in out of my original series 3 BBC micro board if needed.

Yes, the VIA is not critical for the Atom. However, you'll need it if you want to connect a printer to your Atom and some applications (mostly games) use timers and interrupts from the VIA.

Is there a list of all the links on the motherboard? some seem to have been added and i am not sure that is a good or a bad thing.

AFAIK there is no list yet. You can leave the links as they are.

LK1 open -> IMHO this link may only be closed if the Atom only uses 1K of video RAM. IC30 may not be fitted if LK1 is closed.
LK2 closed -> if closed the VIA can interrupt the CPU
LK3 open -> enables interrupts from PL8 (Econet, AtoMMC, also used in the Prophet Business computer)
LK4 erm - didn't find a LK4 on visual inspection
LK5 open -> fixed setting for colour set selection, leave as default
LK6 closed - this is know is 5V regulated PSU
LK7 closed - this is know is 5V regulated PSU

There is a mod on this - a wire running from pin2 or pin 6 of the cassette connector to one of the pins on PL5, the VIA PRINTER I/O port. Any ideas on what this is for?

This is probably the 8th bit for the printer interface. By default the Atom has a 7-bit printer interface. BITD we used PC3 of the 8255 to add the 8th bit. To avoid flickering of the screen we changed LK5 (so we only had only one colour set). Your mod might be something similar.

Does the Atom make a beep thru its speaker on power up? That would be useful to know!!

No, the Atom is a very quite computer. If you power on, press break and then CTRL+G you should here a short beep.

Finally, for now at least, I have two EPROMs in IC21 and IC24. I will take them out to see if I can read off them. They had no cover over their glass until now, so no idea of their condition. Not sure what should be in them. I have just found a hardware guide so I will look into that too.

IC21 is the floating point rom and IC24 is an expansion rom; there are many of them so without a dump of the contents we cannot say anything about it.

Finally finally, There are a lot of 2114 memory chips and I expect there's going to be one or two with issues. Is there a good troubleshooting reference that guides me through the symptoms and where to start looking?

There is a checklist at viewtopic.php?p=60505#p60505

Enjoy your Atom, once you have it working you'll probably want to expand it. Recommended expansions are the AtoMMC, a noise killer and a decent memory board. With these expansions you'll have a great Atom that can be powered from a mobile phone (or generic USB) power adaptor.

[tomkinsg]

Hi Glyn,

I was in a similar position to you recently and posted about it on here. I have two observations which I think will be helpful.

1. Farnell in the US (but only in the US) sell a 5mm power plug that should fit the Atom. It is part number 27-1125. There's a £16 charge to import these to the UK!

2. Of the 2114s, the lower two which are aligned horizontally are critical as they contain page zero. Try removing and swapping with other positions. I found all my ram was actually ok once removed and put back.

Thanks for these tips. So you can buy 15W USB power bricks for around $5 each here, and i have a few spare lying around the house anyway. I could buy some of those 5mm tips from Farnell and can make USBA or USBC to 5mm barrel connector cables and that would be the simplest and most flexible solution to power the Atom that i can think of.

I'd be happy to bring some of those cables or just the barrels back to the UK with me next time I come over the pond! Even the Farnell shipping is $10 locally and the barrels are $0.80 so it makes sense to buy more and help out the community in the process!

thanks!
Glyn

[tomkinsg]

I have acquired an Atom - a rescue from ebay.

Congratulations I'll try to answer a few questions for you.

My board is fully populated except for the 6522 VIA in IC1. I believe it is not critical it be there but I have one that i can slot in out of my original series 3 BBC micro board if needed.

Yes, the VIA is not critical for the Atom. However, you'll need it if you want to connect a printer to your Atom and some applications (mostly games) use timers and interrupts from the VIA.

Is there a list of all the links on the motherboard? some seem to have been added and i am not sure that is a good or a bad thing.

AFAIK there is no list yet. You can leave the links as they are.

LK1 open -> IMHO this link may only be closed if the Atom only uses 1K of video RAM. IC30 may not be fitted if LK1 is closed.
LK2 closed -> if closed the VIA can interrupt the CPU
LK3 open -> enables interrupts from PL8 (Econet, AtoMMC, also used in the Prophet Business computer)
LK4 erm - didn't find a LK4 on visual inspection
LK5 open -> fixed setting for colour set selection, leave as default
LK6 closed - this is know is 5V regulated PSU
LK7 closed - this is know is 5V regulated PSU

There is a mod on this - a wire running from pin2 or pin 6 of the cassette connector to one of the pins on PL5, the VIA PRINTER I/O port. Any ideas on what this is for?

This is probably the 8th bit for the printer interface. By default the Atom has a 7-bit printer interface. BITD we used PC3 of the 8255 to add the 8th bit. To avoid flickering of the screen we changed LK5 (so we only had only one colour set). Your mod might be something similar.

Does the Atom make a beep thru its speaker on power up? That would be useful to know!!

No, the Atom is a very quite computer. If you power on, press break and then CTRL+G you should here a short beep.

Finally, for now at least, I have two EPROMs in IC21 and IC24. I will take them out to see if I can read off them. They had no cover over their glass until now, so no idea of their condition. Not sure what should be in them. I have just found a hardware guide so I will look into that too.

IC21 is the floating point rom and IC24 is an expansion rom; there are many of them so without a dump of the contents we cannot say anything about it.

Finally finally, There are a lot of 2114 memory chips and I expect there's going to be one or two with issues. Is there a good troubleshooting reference that guides me through the symptoms and where to start looking?

There is a checklist at viewtopic.php?p=60505#p60505

Enjoy your Atom, once you have it working you'll probably want to expand it. Recommended expansions are the AtoMMC, a noise killer and a decent memory board. With these expansions you'll have a great Atom that can be powered from a mobile phone (or generic USB) power adaptor.

Love all of this - thank you Roland. I do want to get this onto the econet also - I may be in touch with you on that!

thanks - I'll keep y'all posted in progress and you can be sure i will reach out if i need a helping hand.

thanks
Glyn

Glyn

[jms2]

I'd be happy to bring some of those cables or just the barrels back to the UK with me next time I come over the pond! Even the Farnell shipping is $10 locally and the barrels are $0.80 so it makes sense to buy more and help out the community in the process!

I was hoping you might offer to do that! If you plan to make a trip to the UK, let me know and I'll PM my address. I only want one of the barrels, but I'd be happy to look after a number of them (5 should be more than enough) for any other future Atom owners who need them.

[KenLowe]

I do want to get this onto the econet also

Might be worth having a look at this, then:

viewtopic.php?t=26020

[tomkinsg]

I'd be happy to bring some of those cables or just the barrels back to the UK with me next time I come over the pond! Even the Farnell shipping is $10 locally and the barrels are $0.80 so it makes sense to buy more and help out the community in the process!

I was hoping you might offer to do that! If you plan to make a trip to the UK, let me know and I'll PM my address. I only want one of the barrels, but I'd be happy to look after a number of them (5 should be more than enough) for any other future Atom owners who need them.

So these parts arrived (I ordered 20) but they are not fitting into the atom socket. Grrr. I do not think its the outer diameter but the inner that is the issue. What was the Atom specification?

I confirmed that they are the ordered part and they say the packaging is labelled 5.0mm/2.1mm barrel.

This barrel also fits into the 5.5mm/2.1mm sockets that i have in my parts bucket. Go Figure. So I am now thinking of replacing the atom's 5.0mm with a 5.5mm and using the 5.0mm plug. what a palaver! I don't know if the contacts from the 5.0 sockets align to the existing.

Glyn

[jms2]

Oh no! How annoying. I do apologise!! The Atom Technical Manual doesn't specify what the socket is, but I was sure I had found reference on here to 5.0 x 2.1mm, and measuring the socket seemed consistent with that.

On mine I thought that the outer diameter might still be a bit tight, because the spring contact seemed very stiff. Does the new barrel get past the outer plastic part of the socket?

[tomkinsg]

Oh no! How annoying. I do apologise!! The Atom Technical Manual doesn't specify what the socket is, but I was sure I had found reference on here to 5.0 x 2.1mm, and measuring the socket seemed consistent with that.

On mine I thought that the outer diameter might still be a bit tight, because the spring contact seemed very stiff. Does the new barrel get past the outer plastic part of the socket?

No worries at all. Yes the 5mm does fit in the outer. The inner looks more like 2.5mm. I was thinking that I could drill out the plastic enclosure to 6mm to allow a 5.5mm to fit but I think that would still not fit the inner.

I have tried to fit a 5.5mm/2.1mm socket to the board but the presentation of the pins isn't going to allow for it so I wired it up on some flying leads. It looks cheesy but it sounds great....

On power I hit break and then I get a quiet and short beep from the loudspeaker with every press of ctrl-G. I am taking that as a very very good sign.

I need to make a rgb2hdmi cable and see if I can get a screen up next.

That may have to wait to tomorrow.

[tomkinsg]

I am also in need to get this hooked up to a monitor. I plan to use a RGBtoHDMI that i have for my model B. the wiki (https://github.com/hoglet67/RGBtoHDMI/w ... -Computers) for it says its compatible with Acorn Atom TTL - am i right that is using the video connector PL4? I have the schematic from the same wiki of how to wire it and some parts on order.

I think I must have misread or misunderstood when reading about RGBtoHDMI for the Atom, that I could use the 12-bit board that I have for my Model B with the atom and all I needed to do was wire up an appropriate cable. Reading again this morning, it appears I need the analog board that I do not have.

What are my options for hooking up a monitor to the Atom? I got the RGBtoHDMI working with the Oric1 that I also acquired recently - the basic project of getting that up and running is all good. I could use some more of these RGBtoHDMI boards but they are not cheap.

Glyn

[KenLowe]

I think I must have misread or misunderstood when reading about RGBtoHDMI for the Atom, that I could use the 12-bit board that I have for my Model B with the atom and all I needed to do was wire up an appropriate cable. Reading again this morning, it appears I need the analog board that I do not have.

What are my options for hooking up a monitor to the Atom? I got the RGBtoHDMI working with the Oric1 that I also acquired recently - the basic project of getting that up and running is all good. I could use some more of these RGBtoHDMI boards but they are not cheap.

You could go for one of these, which allows you to connect via VGA and/or a standard RGBtoHDMI board:

viewtopic.php?t=26154

The RGBtoHDMI interface gets added at this point:

viewtopic.php?p=385073#p385073

and finally, it's all up and running here:

viewtopic.php?p=387711#p387711

[1024MAK]

What are my options for hooking up a monitor to the Atom?

For an Atom with the standard monochrome video output (no extra expansion boards to replace the 6847), on the pin header (10 way type known as PL4) at the rear of the board near the DC input socket and the tape cassette socket, pin 9 is a composite video signal and pin 10 is the ground pin for this signal.

Hence I added a phono/RCA socket to the case and wired it to a suitable plug to connect to pins 9 & 10.

I posted some photos on here somewhere… Edit: visit this topic, but note that the photos are later on, so scroll down.

That topic also includes the alternate method of wiring the composite video to the phono/RCA socket of the modulator.

Of course, that assumes you have a TV or monitor that has a composite video input.

Mark