Jump to content
Steverd

Atari 800XL Mystery Mod/Repair?

Recommended Posts

I just got the 800XL and it had a stuck key (fix that), so I opened to clean and found this under the shielding.

This board plugs into U27 with wires to U7, U9 and the PIA.

My guess is some RAM repair.

Every chip is also in a socket, was that normal?

Or maybe this board had a ton of repairs?

 

Thoughts?

mod1.jpg

mod2.jpg

Share this post


Link to post
Share on other sites

Looks like a 256K memory upgrade. Notice the base 8xDRAM chips have *256 designation, vs the originals ending in *64.

 

It's not wizztronics or ICD RAMBO, those appear to have a more rectangular PCB. Can you expose more of that PCB with the tape removed to see if there is any identifying branding? Looks too professional to be a homebrew PCB...

Share this post


Link to post
Share on other sites
Posted (edited)

Looks like a 256k Upgrade to me as well. I have one in my daily driver( with stereo of course). Probably Rambo , but not sure. Mine seems smaller. 

Edited by Paul Westphal

Share this post


Link to post
Share on other sites
20 hours ago, Steverd said:

Every chip is also in a socket, was that normal?

Or maybe this board had a ton of repairs?

Not likely it's had tons of repairs, some XL's are fully socketed (wish mine was :) ), was down to who manufactured it, someone here will let you know

Share this post


Link to post
Share on other sites
Posted (edited)
55 minutes ago, kheller2 said:

Its a newell 256K upgrade.

 

Thank you - looks just like the Newel from photos I found.

NOW my question: SALT 2.05 is showing 40K RAM, is that normal or is my Newell not working?

How else would you test the amount of RAM? The Print FRE (0), shows a little less that 40K

 

IMG_1935.JPG

Edited by Steverd

Share this post


Link to post
Share on other sites
1 hour ago, kheller2 said:

Its a newell 256K upgrade.

 

Bingo, I think that matches the PCB!

 

Image I found from the following thread:

Newel 256k REV.A Memory Upgrade.jpg

 

 

 

 

Share this post


Link to post
Share on other sites
On 4/13/2022 at 4:38 PM, Steverd said:

Thank you - looks just like the Newel from photos I found.

NOW my question: SALT 2.05 is showing 40K RAM, is that normal or is my Newell not working?

How else would you test the amount of RAM? The Print FRE (0), shows a little less that 40K

 

IMG_1935.JPG

 

Is this a SALT cart or a floppy?  Hold down option if you are booting it off a disk.

 

Share this post


Link to post
Share on other sites

Below is a screen shot from eXtended RAM Test

Shows 12 banks = 0192 KB

 

Does that mean my 800XL has 192KB or is that just the extended memory?

192kb plus the 64kb?

 

Thank you everyone

P1080893.JPG

Share this post


Link to post
Share on other sites

Not sure of the version number of that test, they fixed one of them IIRC. Try my EXTEST found in this thread.

And I'll trust what that screen shot shows. The one you got now seems to be showing a Rambo type of memory upgrade with a fixed test program where none of the standard machine ram is being used so that means that 4 banks of extended memory are running the machine. Down four from 16 is 12 banks and this is my main objection to the Rambo way of doing an upgrade. If you bank the wrong bank, your machine crashes and you got cheated out of 4 banks. Did I mention, you got cheated out of 4 banks? If it's all you got then and only then it's better than nothing, but there are upgrades that will give you all the banks you bought.

 

It's only 192K, you don't get to count the original 64K because they are just sitting there using up power and doing nothing at all. It's only your extended memory that is at work, but you can't use 64K (4 banks) of it because those are being used by the Atari Operating System. It would appear so at least. If banking bytes A3, A7, AB and AF are missing from my test too then it's just conformation that a Newell 256K is just a one off 192K Rambo with a different set of banks being used for base ram.

Share this post


Link to post
Share on other sites
On 4/18/2022 at 5:06 AM, 1050 said:

It's only 192K, you don't get to count the original 64K because they are just sitting there using up power and doing nothing at all.

There is literally only 256KB total in the system. 64KB + 192KB. Look at the motherboard in the original post - 8x256kbit chips. The chips on the additional PCB only contains logic chips.

 

@Steverd - there is a slightly updated version of that memory tester available here:

http://atari.sk/extended-ram-test-0-22-0-xram0220-xex/

 

For reference, here is what 0.22 looks like from a system of mine with an ICD Rambo 256K 800XL. I'm curious if the newer version presents differently that this on your system. I'm curious about the difference of missing row at $Ax vs $8x.

 

1757984010_RAMBOXRAM2201024.thumb.jpg.6cf6a3c3581e7938a6bc608163fb0ab6.jpg

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...