Atom boots after 26 years!

discussion of games, software, hardware & emulators relating to the Acorn Atom
markdryan
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Atom boots after 26 years!

Postby markdryan » Mon Aug 21, 2017 1:39 pm

I bought this Atom from a school friend in the summer of 1991 for the princely sum of 15 pounds. I played around with it for an afternoon and then put it in a box in my dad's garage, where it remained for 26 years. I turned in on yesterday and amazingly it worked. As far as I can tell it's a basic model with 2KB of RAM.

I have some questions:

  • There's a wire protruding from the back of the computer. Seems to be poking out through the video exit. No idea what this is for and there's no connector. Does anyone know what this might be?
  • When I run a program I see a lot of distortion or snow on the screen. I've looked at some youtube videos of various Atoms and I see similar distortion on some of this videos so I guess it's not just mine. Why does this happen and is there anyway to get rid of this?
  • To make the Atom usable, I'm going to need some sort of SD card interface and some more RAM. What are my options? I've seen the list of Atom hardware here: http://www.stardot.org.uk/forums/viewtopic.php?f=13&t=8168&p=86259&hilit=Atomic+facts#p86259. Are any of these boards still available for purchase? Are they easy to fit? Is soldering required?
  • I seem to have an 8V power supply. Will this prevent me from installing any of the upgrades?

Thanks in advance for your help,

Mark
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atom.jpg

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martinw
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Re: Atom boots after 26 years!

Postby martinw » Mon Aug 21, 2017 1:51 pm

Excellent, another working Atom in the wild :)

If it were me I'd start off by getting myself a screw driver and removing the two screws beneath the case (look like wood screws when you've taken them out) and take some pictures of the inside ;)

Martin

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martinw
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Re: Atom boots after 26 years!

Postby martinw » Mon Aug 21, 2017 1:56 pm

This is where you want to get eventually IMVHO, it's ace :)

IMG_5275.JPG


Martin

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oss003
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Re: Atom boots after 26 years!

Postby oss003 » Mon Aug 21, 2017 2:00 pm

Hi Mark,

good to hear that your Atom is still working.
There's a wire protruding from the back of the computer. Seems to be poking out through the video exit. No idea what this is for and there's no connector. Does anyone know what this might be?

If the cable is connected to pins 9 and 10 of PL4, then it's a monochrome composite video output.
Much better quality than the RF output.

When I run a program I see a lot of distortion or snow on the screen. I've looked at some youtube videos of various Atoms and I see similar distortion on some of this videos so I guess it's not just mine. Why does this happen and is there anyway to get rid of this?

This is normal, the CPU and videprocessor share the same bus for video memory and when the CPU is writing data to the video memory, it is shown as noise on the screen. You can get rid of this by building a noisekiller circuit or use a colourboard with noisekiller.

To make the Atom usable, I'm going to need some sort of SD card interface and some more RAM. What are my options? I've seen the list of Atom hardware here: http://www.stardot.org.uk/forums/viewtopic.php?f=13&t=8168&p=86259&hilit=Atomic+facts#p86259. Are any of these boards still available for purchase? Are they easy to fit? Is soldering required?

For an SD-card interface, the AtoMMC is a very good solution and is still available. You can contact sir morris(Charlie) for one.
Phills RAMROM board is a good option to fill your memory with 32 kB RAM, 8 utilty roms and some other nice features. Please contact prime (Phill) for this board. Both boards fit in the existing sockets and don't need soldering however it's better to replace the existing bad sockets on the mainboard with turnpin sockets.

I seem to have an 8V power supply. Will this prevent me from installing any of the upgrades?

The 8V is transformed to 5V in your Atom and the Atom, including upgrades, are working at 5V.
Most people have made links LK6/7 in the Atom and are using a 5V power supply because these are easier to get.

Greetings
Kees

markdryan
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Re: Atom boots after 26 years!

Postby markdryan » Mon Aug 21, 2017 4:05 pm

Two more images, one of the inside of the atom and one that focuses in on the cable prodtruding from it. It seems to be connected to pins 5 and 10.
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atominside.jpg
atomcable.jpg

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oss003
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Re: Atom boots after 26 years!

Postby oss003 » Mon Aug 21, 2017 4:51 pm

Pin 9 is definitly composite video out but the GND is connected to the wrong pin.
Pin1 is connected to PC3 of the 8255 which is the colourselect signal (CSS).
After a BREAK, PC3 is 0V so if you measure pin1 you will probably measure 0V until you change the colourset (?#B002=8).
The GND should be connected to pin 10 of PL4.

Greetings
Kees
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martinw
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Re: Atom boots after 26 years!

Postby martinw » Mon Aug 21, 2017 7:20 pm

Gotta love those early springy keys too :)

Martin

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martinw
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Re: Atom boots after 26 years!

Postby martinw » Mon Aug 21, 2017 7:27 pm

Your gonna need one of these ...

IMG_5295.JPG


The one I have does require a few soldered wires beneath the PCB though.

Martin
Last edited by martinw on Mon Aug 21, 2017 7:42 pm, edited 3 times in total.

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martinw
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Re: Atom boots after 26 years!

Postby martinw » Mon Aug 21, 2017 7:35 pm

And one of these ...

IMG_5318.JPG


IMVHO 8)

Martin

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DutchAcorn
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Re: Atom boots after 26 years!

Postby DutchAcorn » Mon Aug 21, 2017 8:18 pm

markdryan wrote:[*]I seem to have an 8V power supply. Will this prevent me from installing any of the upgrades?[/list]

Your Atom does not have much memory installed. If you install upgrades it will draw more current, the voltage regulators will dissipate more heat. They can get so hot that the case can get damaged. The Atom technical manual advises to alter the board to take a 5V regulated PSU for a fully expanded Atom.
Paul

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1024MAK
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Re: Atom boots after 26 years!

Postby 1024MAK » Mon Aug 21, 2017 8:32 pm

Aye, but these days, there is an alternative. I don't think anyone has tried it, but it should be possible to fit RECOM or TRACO DC-DC converter/regulators in place of the two series voltage regulators (IC53 and IC54).

These have the advantage that they are very efficient (draw less input current for the same output current), plus they run cool 8) Note that the existing 8V external power supply unit would still be used.

Alternatively, fit links LK6 and LK7 and use a 5V regulated switch mode power supply rated at 2.5A minimum. Make sure of the polarity (an incorrect polarity will kill most of the chips) and fit a label warning that the machine is now 5V DC only.

Also if you fit a modern ROM/RAM board, you won't need the current hungry 2114 NMOS SRAM chips for main memory.

Mark
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markdryan
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Re: Atom boots after 26 years!

Postby markdryan » Mon Aug 21, 2017 10:13 pm

Thanks for all the replies

Also if you fit a modern ROM/RAM board, you won't need the current hungry 2114 NMOS SRAM chips for main memory.


Does this mean that if I just fit a modern RAM board such as the RAMROM board from prime mentioned above, I can stick with the 8V power supply? Does anyone have an Atom configured this way (2k basic RAM, 32k RAM/ROM board, 8v power supply)?

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roland
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Re: Atom boots after 26 years!

Postby roland » Tue Aug 22, 2017 6:34 am

I don't have such a set up but I expect it to work if you consider to replace the video memory by a 8kB static cmos ram ( viewtopic.php?f=44&t=13531&start=60#p177979 ) which draws much less current than the 2114's and it also adds 2kB extra memory.

However, I'd still advice to make the switch to 5V just in case you're going to expand your Atom with AtoMMC and later perhaps with other boards like a (pi)tube 2nd processor. With 5V you are ready for the future 8)
256K + 6502 Inside
MAN WOMAN :shock:

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CMcDougall
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Re: Atom boots after 26 years!

Postby CMcDougall » Tue Aug 22, 2017 4:06 pm

1024MAK wrote: fit links LK6 and LK7 and use a 5V regulated switch mode power supply rated at 2.5A minimum. Make sure of the polarity b]

no need for 2.5amp , when mine was oldskool & behaving badly, Roland noted it only used 0.9amp, so any USB mobile phone charger will do, these are 1amp, the tablets adaptors spit out 2amp tops (so good for a master compact etc)
ImageImageImage

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1024MAK
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Re: Atom boots after 26 years!

Postby 1024MAK » Tue Aug 22, 2017 4:17 pm

The actual current consumption very much depends on what semiconductors (chips/type of chips) and add on boards are fitted... or not fitted...

For example, there are many versions of the 2114 SRAM, some are VERY power hungry, others are made using low power CMOS and hardly use any current in comparison.

Mark
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markdryan
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Re: Atom boots after 26 years!

Postby markdryan » Tue Aug 22, 2017 11:50 pm

Thanks again for all the advice. I'm going to try to make the switch to 5Vs. If this works I'll start sourcing some upgrades.


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