48K 400

[Panther]

I decided to upgrade a 400 sitting here just for the heck of it. I found two versions, one by Claus Buchholz, and another one that actually appeared to be closer to the factory 48K upgrade as far as motherboard modifications. I decided to use the version by Claus.

 

The memory card mods were quite straightforward:

 

The motherboard changes were a bit more work, but not too bad:

 

Success:

 

Thank you, Claus.

 

Edited April 10, 2016 by Panther

[J.Ivy]

Very cool.

 

Is modding the motherboard the only way that you can use this much ram?

[Panther]

Yes, since without mods the 400 and 800 can only handle up to 32K per memory slot, and the 400 has only one memory slot.

[ACML]

Yes, since without mods the 400 and 800 can only handle up to 32K per memory slot, and the 400 has only one memory slot.

Wow! The mods look like it's not too extensive. Can you post the design schematics? I just happen to have 8 4164s lying around.

Edited April 10, 2016 by ACML

[ClausB]

Nice work, Panther.

 

Here's the article:

http://atariage.com/forums/topic/123207-expanding-the-400/?do=findComment&comment=1488304

[Panther]

Thanks, I assembled those into a .pdf for easier storage.

 

 

Atari 400 48K Upgrade.pdf

[Panther]

For a certain person getting ready to perform this upgrade, here are some photos of the 74LS02 and wiring without the shrink tubing over it. Note that I did not use a socket and opted to wire directly to the chip. I also removed the unused pins and trimmed the remaining leads.

 

 

[Marius]

Some time ago i did this too but i experienced issues with atarimax 8mbit carts. Other carts did not have issues.

 

Do you have those issues too?

[Panther]

Unfortunately, I barely did more than see if the memory showed up. This 400 doesn't really get used at all. I'll hook it up sometime and test things more thoroughly.

[KLund1]

Panther,

Thanks a lot for the additional photos. Very, very helpful !!!!!

[TechCowboy]

Unfortunately, I barely did more than see if the memory showed up. This 400 doesn't really get used at all. I'll hook it up sometime and test things more thoroughly.

I see this was quite some time ago Moonsweeper; did you ever do any testing?

[Awch]

I see this was quite some time ago Moonsweeper; did you ever do any testing?

Seconded. I've got the chips and am looking to upgrade my 400 soon. Thanks for any help!