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400 Memory upgrades

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I have a couple 400's I want to upgrade to 48K.

I know there are ways to change a 16K card to 48K. Are there kits out there for sales other than BestE? Those prices have really gone way up.

Or are there simple instructions some where in here that easily show how to do the upgrade? Hopefully with some pictures. I have googled and have found multi page detailed guides to do it, but they had terms, parts, and details I did not understand. I have another 400 that I upgraded a few years ago with an Atari 400 48K Expansion Kit. I could use that as a template for the MB jumper wires perhaps.

I also need a cart door spring. I can't find any at Home depot or Lowes that work or fit.

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There are two versions of this mod that I found. There's one by Gary A. Crowell which appears to be compatible with the factory upgrade, as the changes to the 400 or the same, just four jumper wires, and the the mods to a 16K card. Then there's a version by Claus Buchholz which requires a bit more modding to the 400, but less changes to the RAM card. I went with the version by Claus and it worked well, though I'm sure the other version is fine too.

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Thanks,

I could not find the Gary A. Crowell version. link?

I had found the Claus Buchholz method, and it is just bit beyond my skills. I looked at this

http://atariage.com/forums/topic/251346-48k-400/?hl=%2Bclaus+%2Bbuchholz

that had some pictures. After reading the article's directions and looking at the pictures, I saw enough differences that I would most likely screw it up and kill the 400. The Ram card I think I could do. I would need some serious hand holding for the rest.

Like the parts list shows 2 resistors , but I see three in those pictures. Or this quote "Finally, solder one of the 680 ohm resistors between pin A under the cartridge slot and the nearest ground connection" I would not know a ground connection from a washing machine.

Then there is sourcing the parts. This is as close as I could come.

http://www.ebay.com/itm/DRAM-64kx1-Dynamic-RAM-64k-x-1-200ns-HM4864P-3-MB8264-20-M5K4164NP-20-8-pieces-/251666089003?hash=item3a9877c42b:g:glkAAOxy-WxTA3Xp

http://www.ebay.com/itm/2pk-74LS158-ICs-Multiplexer-/370675771208?hash=item564dff6748:m:m8GcrsrbyZKEmP70MVd8mzQ

http://www.frys.com/search?storeNo=All+Products&search_type=regular&sqxts=1&cat=&query_string=74ls02

http://www.frys.com/product/5359038?site=sr:SEARCH:MAIN_RSLT_PG

This is the closest resistor I could find at my work. I'm sure we have the right one, but I can't find it.

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This looks just as complicated. I'll have to read them both more carefully with a 400 open so I can follow along on the hardware as I read the directions.

I work a frys,and get the parts for near free, IF we carry them. Big IF.

I know we do not have the 74LS158, or the drams ic's. Mouser, Digi-Key, and Jameco for those.

But we should have the cap, and resistors, but I do not know enough about there descriptions to find the right ones. If you have a couple extra minutes, could you take a quick look, and send a link if you find the right ones?

Thanks for all your help!

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I'm available to help. Below is a link to the article which includes diagrams that show where "the nearest ground connection" is, and other details.

 

 

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If you look further up the page on that link you'll see some detailed images of my installation, which should make it quite simple.

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As for the parts, forget Fried Electronics and eBay. Look at Mouser, Digi-Key, and Jameco.

 

DRam 4164

Mouser, Digi-Key not carried

Jameco estimated shipping date 8/1

Any other good sources??

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41464, not 4164. Jameco item # 41574.

 

I purchased mine from Jameco. They don't specify the brand, so they could change order to order, but the ones I received are NEC.

Edited by Panther

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No, you DO want 4164 or equivalent 64Kx1 DRAMs. The 41464 chips are 64Kx4 which will not fit in a 400 (but will in a 600XL).

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Oops! That's what I get for getting up too early in the morning. I had been discussing a 600XL memory upgrade and got confused about what I was replying to. Yes, 4164. Jameco part # 41662...which, yes, they appear to be out of.

Edited by Panther

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As an aside: Claus' upgrade guide mentions a GTIA upgrade for the 400. I assume that this is just a drop in replacement.

But since an article is mentioned, it would seem that there are caveats.

First caveat to cross my mind would be: Must the GTIA be the NTSC one?

Can somebody elobarate on what to keep in mind, when attempting a CTIA replacement?

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Jameco now shows a ship date of 5/13/16, so it looks like they're getting more in stock this week.

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Has anyone tried to use the 64k mod from Claus' upgrade?

 

I haven't, but the problem is what are you going to use it for? A 16KB ramdisk? It just doesn't seem to serve much use.

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I have never tried it either. A 16K RAMdisk might be useful for MEM.SAV and DUP.SYS if you're a DOS 2 user. The 52K contiguous RAM might cause trouble with the OS too.

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I have never tried it either. A 16K RAMdisk might be useful for MEM.SAV and DUP.SYS if you're a DOS 2 user. The 52K contiguous RAM might cause trouble with the OS too.

I doubt it would cause problems with the OS, Mosaic made a 64K bank selectable memory card, up to 3 could be installed in the 800, that used 4-4k banks accessible in the 48-52K range. The extra memory was even usable with BASIC, a "POKE 106,208" set RAMTOP to 52K, and there were other POKEs to select bank. SYNFILE+ was able to use the extra memory provided by both AXLON and MOSAIC boards.

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I successfully installed the expansion variant of Claus. Works great.

Even SDX boots up.

The enhancement for the last 16k is on my list now, but I need to get the IC first.

 

PS: I used two 1kOhm resistors, because I hadn't the 680 Ohm ones. Still works.

Edited by JoSch
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Oops, I forgot that my 64K option uses a 16K bank like AXLON, so 52K is no issue.

 

Can't you also upgrade the OS so you don't have to split up the RAM upgrade? Or is due to a preference to keep the OS ROM stock?

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I have a couple 400's I want to upgrade to 48K.

I know there are ways to change a 16K card to 48K. Are there kits out there for sales other than BestE? Those prices have really gone way up.

Or are there simple instructions some where in here that easily show how to do the upgrade? Hopefully with some pictures. I have googled and have found multi page detailed guides to do it, but they had terms, parts, and details I did not understand. I have another 400 that I upgraded a few years ago with an Atari 400 48K Expansion Kit. I could use that as a template for the MB jumper wires perhaps.

I also need a cart door spring. I can't find any at Home depot or Lowes that work or fit.

 

I just purchased a cart door spring from Bradley at Best.

 

400 - door spring - CO14104 - $1

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