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mimo

Atari 400: Odd keyboard behavior

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I have a strange problem with my Atari 400.

I have a new keyboard from BE, and the old semi faulty keyboard.

When in MEMO PAD, the new keyboard is fine and registers all key presses, the old keyboard only registers a few keys.

With BASIC cart inserted, neither keyboard is registered.

I have tried the BASIC cart in my 800 and it works fine.

I have also swapped the OS and the RAM from the 800 and get the same results.

 

 

Please help me to save this 400, any ideas what else I should check? I only have basic tools and a digital multi meter.

I have a very dead (red screen) 400 and a working 800 that I could swap parts from.

 

 

Cheers

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Can that be something as simple as dirty contacts on the 400's cart slot? Not the cart but the slot itself?

Do you have Atariwriter cart you could try?

 

And I'm not sure how it works (don't have a working 400/800 setup ) but if you boot to a floppy with DOS on it with no cart, can you access the menus and perform commands and stuff?

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Does the machine say "Ready" when you start with Basic inserted ?

 

If not, then there's some bad contact and chances are it's just causing a lockup.

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Will try and clean the slot tonight.

I don't have Atari writer cart

It's only 16k, will the menu even load?

The READY prompt comes up,can't remember if the cursor flashes

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Cleaned the cart and the slot, no improvement.

Did a 48K RAM upgrade, everything works fine except BASIC and the Keyboard not playing together nicely.

In game, the ketboard works fine, with my SIDE cart the keyboard works fine :mad: :_(

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You can't possibly have only 1 basic cart, can you? I think its a rule that all 8bitters are required to have like at least 3 Basic carts in their collection. Maybe 4 of them along with the requisite 3 Star Raiders, 3 Pac Man, 2 Space Invaders, and 2 Donkey Kong carts?

 

:)

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you are correct on the other carts, but I really only have 1 Basic cart, I'm too kind and have given loads of them away over the years

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you are correct on the other carts, but I really only have 1 Basic cart, I'm too kind and have given loads of them away over the years

Do you have Star Raiders? It uses keyboard input.

Numbers (0-9) = speed/throttle setting

C = Computer On/Off

S = Shields On/Off

T = Tracking On/Off

G = Galactic Map

H = Hyperspace

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you are correct on the other carts, but I really only have 1 Basic cart, I'm too kind and have given loads of them away over the years

Do you have Star Raiders? It uses keyboard input.

Numbers (0-9) = speed/throttle setting

C = Computer On/Off

S = Shields On/Off

T = Tracking On/Off

G = Galactic Map

H = Hyperspace

 

Yes, I have star raider (label variation) and the key inputs work fine. I have noticed that when carts are in the slot the video output is much worse than without. The exception to this is the side cart which has lovely crisp video even through rf.

Basic still refuses to work in the 400 but works fine in my 800

 

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you are correct on the other carts, but I really only have 1 Basic cart, I'm too kind and have given loads of them away over the years

Do you have Star Raiders? It uses keyboard input.

Numbers (0-9) = speed/throttle setting

C = Computer On/Off

S = Shields On/Off

T = Tracking On/Off

G = Galactic Map

H = Hyperspace

 

Yes, I have star raider (label variation) and the key inputs work fine. I have noticed that when carts are in the slot the video output is much worse than without. The exception to this is the side cart which has lovely crisp video even through rf.

Basic still refuses to work in the 400 but works fine in my 800

Have you checked the outputs of the voltage regulators on the side board of the 400? I believe low voltage on the +5V supply could be a possible cause of these symptoms. If the +5V supply is marginal the extra load caused by inserting the BASIC or other cartridge could be causing the keyboard or video issues. While the SIDE cartridge doesn't have any issues this may be because the modern electronics it uses tend to draw less power than the older types.

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Checked the voltages, and they are fine. Replaced the power board with a known good one, same issues :mad:

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Anyone noticed an increase in rf interference when a 48k mod is installed?

I have fitted 2 mods and both show much more noise on screen with the mod

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