New Atom owner (soon)

discussion of games, software, hardware & emulators relating to the Acorn Atom
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myelin
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New Atom owner (soon)

Post by myelin » Thu Jul 05, 2018 9:32 pm

After staring at it on eBay for a couple of weeks, I finally cracked and bought the 200 euro Atom from backtoyourpast (pricey, but out of the Atoms I've seen whose owners will ship to the USA, it seemed bearable). So... I expect to be an Atom owner once it arrives in San Francisco :)
Last edited by myelin on Thu Jul 05, 2018 9:34 pm, edited 1 time in total.
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Elminster
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Re: New Atom owner (soon)

Post by Elminster » Thu Jul 05, 2018 10:31 pm

I am waiting for Roland to reinvent his Atom design. 200 euros seems a bit steep.

Failing that I hope to magically acquire one.

waltermixxx
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Re: New Atom owner (soon)

Post by waltermixxx » Thu Jul 05, 2018 11:49 pm

200 euro's for an Atom is not bad,
I've seen it as high as $800.00 or so for an Atom.
or no Atom's at all. Good for you for getting one.

I finally got one for myself as well. And I love it.
Upgraded it to 32k, and added a coco 2 composite video board to it,
as a colour board.

Please make sure you get one of those MMC interfaces for it as well,
very reasonably priced and totally necessary for reliving some of those
gaming memories. :)

Congrats on your purchase, Bottom line, Congrats... :)

Cheers. :)

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hoglet
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Re: New Atom owner (soon)

Post by hoglet » Fri Jul 06, 2018 5:45 am

myelin wrote:
Thu Jul 05, 2018 9:32 pm
After staring at it on eBay for a couple of weeks, I finally cracked and bought the 200 euro Atom from backtoyourpast (pricey, but out of the Atoms I've seen whose owners will ship to the USA, it seemed bearable). So... I expect to be an Atom owner once it arrives in San Francisco :)
This is actually a very good price for decent Atom, and the Issue 5 atom is definitely the one to have.

What's you plan in terms of extensions?

AtoMMC2 and some kind of RAM/ROM board are the two "must-have" Atom extensions.

For a nice, clean video output from the 6847 I use a custom scan convertor which works very well, and doesn't require any mods to the Atom:
https://github.com/hoglet67/AtomVGAWing
viewtopic.php?p=58741#p58741

Dave
Last edited by hoglet on Fri Jul 06, 2018 5:46 am, edited 1 time in total.

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myelin
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Re: New Atom owner (soon)

Post by myelin » Sun Jul 08, 2018 2:41 am

hoglet wrote:
Fri Jul 06, 2018 5:45 am
What's you plan in terms of extensions?
Not sure yet! AtoMMC2 seems like an excellent start.

I like the look of your scan converter. Also, do you think your RGBtoHDMI hardware could be adapted to work here? I guess you would need comparators on the inputs...? I'm still figuring out how the whole Y/PA/PB video thing works.
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8bitkick
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Re: New Atom owner (soon)

Post by 8bitkick » Sun Jul 08, 2018 4:34 am

myelin wrote:
Thu Jul 05, 2018 9:32 pm
After staring at it on eBay for a couple of weeks, I finally cracked and bought the 200 euro Atom from backtoyourpast (pricey, but out of the Atoms I've seen whose owners will ship to the USA, it seemed bearable). So... I expect to be an Atom owner once it arrives in San Francisco :)
Hey congratulations I've just been getting my Atom running too. I imagine there aren't many in California!?

Until you get your MMC this might be useful. I just saw your post which prompted me to get in online...

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myelin
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Re: New Atom owner (soon)

Post by myelin » Sun Jul 08, 2018 6:55 am

8bitkick wrote:
Sun Jul 08, 2018 4:34 am
Until you get your MMC this might be useful. I just saw your post which prompted me to get in online...
Thank you! Yes, that'll be super useful! Are you bringing your Atom to VCF? There's a slight chance that mine might arrive in time...
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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hoglet
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Re: New Atom owner (soon)

Post by hoglet » Sun Jul 08, 2018 7:58 am

myelin wrote:
Sun Jul 08, 2018 2:41 am
Also, do you think your RGBtoHDMI hardware could be adapted to work here? I guess you would need comparators on the inputs...? I'm still figuring out how the whole Y/PA/PB video thing works.
From a timing point of view I'm sure it could be made to work.

The only problem is the Y/PA/PB signals are relatively low voltage swing and tri-level (with some redundancy).

Figure 10 in the 6847 data sheet best explains this.

In the FPGA I use the differential LVDS I/O cells rather than external comparators. Each of PA and PB uses a pair of LDVS I/O cells, which allows comparison against two different thresholds. This gives you the tri-level sensing. The Y signals is clamped with a proper back-porch clamp circuit to restore the black level.

I'll check the DipTrace schematic and PCB design into github this morning.

Dave
Last edited by hoglet on Sun Jul 08, 2018 8:38 am, edited 3 times in total.

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8bitkick
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Re: New Atom owner (soon)

Post by 8bitkick » Sun Jul 08, 2018 3:36 pm

myelin wrote:
Sun Jul 08, 2018 6:55 am
8bitkick wrote:
Sun Jul 08, 2018 4:34 am
Until you get your MMC this might be useful. I just saw your post which prompted me to get in online...
Thank you! Yes, that'll be super useful! Are you bringing your Atom to VCF? There's a slight chance that mine might arrive in time...
I was planning to bring my Atom. I can start another thread as we need to sort out logistics for the day...

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myelin
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Re: New Atom owner (soon)

Post by myelin » Tue Jul 10, 2018 9:24 pm

hoglet wrote:
Sun Jul 08, 2018 7:58 am
The only problem is the Y/PA/PB signals are relatively low voltage swing and tri-level (with some redundancy).

Figure 10 in the 6847 data sheet best explains this.

In the FPGA I use the differential LVDS I/O cells rather than external comparators. Each of PA and PB uses a pair of LDVS I/O cells, which allows comparison against two different thresholds. This gives you the tri-level sensing. The Y signals is clamped with a proper back-porch clamp circuit to restore the black level.
Oh, I see now -- you're using the differential inputs to compare against voltage references, which explains the AH/AL signal names :) So you need quite a few more inputs into the system than when just reading an RGB signal.
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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