Try to repair 800XL (again) got working 600XL now

[wiliv]

Some time ago I tried to repair an 800XL which gave just a black screen. http://www.atariage.com/forums/topic/164042-black-screen

 

Now I found a working 600XL, which is cool in itself ofcourse (typed in some basic programs doing graphics and sound, I don't have a SIO cable yet).

 

But I still want to try to get the 800XL working too, now that I can swap parts...

 

So I started swapping, one by one, testing each time. The delay line (U29) as was hinted, the two ROMs, the MMU, then all five major ICs. No change whatsoever. (Put the 600XL back together, it still worked).

 

The only thing I can't swap is the RAM, so I guess there's a fair chance that's where the problem is. Am I correct that the RAMs from the 600 can't be used in the 800? Can you simply remove some of them and run with less memory like you do on a PC (guess not)? Can compatible RAM chips be found in other (non-atari) vintage computers ?

 

I also did a heat test, leaving it powered for some time and then feeling the ICs. The RAMs seemed all hot but not very hot, although I find it difficult to tell.

 

Thanks for any further hints.

 

Wim.

[mimo]

correct, you cannot use the ram from a 600 in an 800xl

[Rybags]

You might try swapping the top 4 RAM chips with the bottom 4. It won't fix anything but might enable the machine to actually get as far as the Self-Test. 800XL uses 1-bit RAMs, so they all contribute to any RAM access.

 

The C64 (breadbox type, not sure about later slimline type) uses the same type of RAM ICs (4164) so you could use that as a donor. Old ISA graphics cards for PCs are also a potential source of compatible RAM.

 

Problem with using a C64 is that the RAM will most likely be soldered into it, so you'd be up for a bit of work.

 

 

ed - if you got utterly desperate you could probably use 256Kx1 chips or even a 32-pin SIMM from an ancient PC. But for a SIMM you'd need a whole bunch of soldering, and need to tie unused addressing lines to GND.

 

Likewise you could use 64Kx4 ICs like used in an XEGS, but they'd need to be mounted in an external board and you'd need a whole bunch of ugly wiring.

Edited August 22, 2010 by Rybags

[zylon]

The later slim C64 uses a different chip setup. It'd have to be an older style one if using donor chips. The RAM chips are still available new cheaply from Jameco.

[wiliv]

IT WORKS!!

 

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

So, in the end I could have done it without the 600XL...but now I have two. Next project will be connecting a 1050 without having the PSU and SIO cable, otherwise there's not much I can do with them.

 

Thanks all for the help.

 

Wim.

[Rybags]

Good stuff... that's another source. Old PC motherboards often have onboard cache.

 

Since you've been looking around for RAM... another worthy project which is fairly simple is dropping a pair of 4464 RAMs into the 600XL, then a few cuts and bit of wiring/soldering to bring it to 64K internal.

[zylon]

Good stuff... that's another source. Old PC motherboards often have onboard cache.

 

Since you've been looking around for RAM... another worthy project which is fairly simple is dropping a pair of 4464 RAMs into the 600XL, then a few cuts and bit of wiring/soldering to bring it to 64K internal.

I've thought of modding mine, but found a 1064? add-on instead. All the listings of this mod never have how-to pics.

[Arkanoid_376970]

I've thought of modding mine, but found a 1064? add-on instead. All the listings of this mod never have how-to pics.

agreed... does anyone know a good how-to guide for the 64K internal mod? also, can the 1064 still work with the mod done? (i.e. still add 48K to the system?)

[Rybags]

64k_upgrade_600xl-1.txt

 

That's the description for the upgrade I did. You don't need to remove the resistor as it decribes, I just left it there and cut the trace instead.

 

You can't use the 1064 in conjunction with it, the 1064 disables internal RAM, doesn't add to it.

[sup8pdct]

I've thought of modding mine, but found a 1064? add-on instead. All the listings of this mod never have how-to pics.

agreed... does anyone know a good how-to guide for the 64K internal mod? also, can the 1064 still work with the mod done? (i.e. still add 48K to the system?)

 

It may, but best not to. The mod to 64k internal removes a chip that deselects the top 48K internal. The 1064 has circuitry to select the top 48K of address space for ram on the 1064.

So any access to ram above 16K will be doubled up which may cause major errors.

 

James

[Rybags]

Actually, the 1064 supposedly disables all internal RAM (via EXTSEL ?)

 

Most of the work for the 64K internal mod is to connect the 2 high order address bits into the RAS/CAS select logic.

Edited August 25, 2010 by Rybags

[Arkanoid_376970]

what if the 1064 was modded to not disable the RAM?

[Rybags]

Then the system probably wouldn't work at all.

 

You can't just chuck memory into an Atari and have it work - there's only 64K address space and you either need to utilise or extend on the memory mapping logic that's built in.

 

A mod to allow the 1064 to use the RAM in similar fashion to e.g. the 320XL upgrade would be a good idea... but the 1064 is kinda rare and worth preserving as it is.

[sup8pdct]

Actually, the 1064 supposedly disables all internal RAM (via EXTSEL ?)

 

 

No it doesn't. The 1st 16k is always internal, the rest is in the 1064.

If you don't believe me, check out the schematics of both the 600xl and the 1064.

 

James

[sup8pdct]

what if the 1064 was modded to not disable the RAM?

 

I have actually done this many years ago while tinkering, but I also removed the internal ram to avoid conflicts..

Will need to look at schematics to which gate(s) to bridge.

 

James

[SnapCraft]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

[svenski]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

[SnapCraft]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

[svenski]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

 

Thanks, I found this:

 

eBay Auction -- Item Number: 310127868116

 

but he won't ship to the UK (which is a bummer) - these appear to be 64K chips - would these be any good? I've got a 800XL with fried RAM, which I'd like to get going.

[19Echo]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

 

Thanks, I found this:

 

eBay Auction -- Item Number: 310127868116

 

but he won't ship to the UK (which is a bummer) - these appear to be 64K chips - would these be any good? I've got a 800XL with fried RAM, which I'd like to get going.

 

I have to stop by my local electronics store that carries off the wall stuff. I'll see if he has any of these. If so, i'll be more than happy to pick some up and ship them to you provided you pay the actual cost

[svenski]

I have to stop by my local electronics store that carries off the wall stuff. I'll see if he has any of these. If so, i'll be more than happy to pick some up and ship them to you provided you pay the actual cost

 

Hey thanks, that would be great - thanks for the offer.

[19Echo]

I have to stop by my local electronics store that carries off the wall stuff. I'll see if he has any of these. If so, i'll be more than happy to pick some up and ship them to you provided you pay the actual cost

 

Hey thanks, that would be great - thanks for the offer.

 

sure, Ill let you know

[sloopy]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

 

Thanks, I found this:

 

eBay Auction -- Item Number: 310127868116

 

but he won't ship to the UK (which is a bummer) - these appear to be 64K chips - would these be any good? I've got a 800XL with fried RAM, which I'd like to get going.

 

eBay Auction -- Item Number: 170596146010

 

cheaper, and ships world wide... and work well...

 

 

sloopy.

[svenski]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

 

Thanks, I found this:

 

eBay Auction -- Item Number: 310127868116

 

but he won't ship to the UK (which is a bummer) - these appear to be 64K chips - would these be any good? I've got a 800XL with fried RAM, which I'd like to get going.

 

eBay Auction -- Item Number: 170596146010

 

cheaper, and ships world wide... and work well...

 

 

sloopy.

 

Sloopy, if I use these how does it affect the XL's operation? Presumably I'm going to have memory addressing issues or need to do some soldering? Sorry for the dumb questions

 

Edit: to explain what I want to do

I have an as new in box 800XL with fried RAM (presumably why it is still as new) which I'd like to fix so ideally I'd like to fix the RAM without doing any sort of mod which would defeat the object as far as this 800XL is concerned.

Edited February 11, 2011 by svenski

[sloopy]

I found a D4164C-15 on an 8088 PC board. Replacing the first (I was lucky) ram chip brought the 800XL to live All selftests worked. Always feels good if effort is finally rewarded.

 

Wow. I am about average when it comes to repairing old computer/consoles. I had the same problem (powered on [LED], black screen). I typed in the D41664C-15 on eBay and ordered a few (just in case). Sure enough, 2 were dead and one was previously broken .

 

And, yes, it works! A 800XL back from the dead! Oh yeah...did I mention it was $5 (sure, about $15 all told, but still)?

 

So, all you need is to swap out the first (bad) ram chip with one of these?, or do you need to pull and swap all four?

 

I replaced 5 at once then slowly sub'ed back in the old chips. Turned out 2 were dead. Yes, I did keep one of the new ones in the top slot (I don't know if that's required). It passed 3 memory tests in a row and played game carts. I'll be trying some disks this weekend. Bringing a console back is one of the greatest feelings in the world.

 

Thanks, I found this:

 

eBay Auction -- Item Number: 310127868116

 

but he won't ship to the UK (which is a bummer) - these appear to be 64K chips - would these be any good? I've got a 800XL with fried RAM, which I'd like to get going.

 

eBay Auction -- Item Number: 170596146010

 

cheaper, and ships world wide... and work well...

 

 

sloopy.

 

Sloopy, if I use these how does it affect the XL's operation? Presumably I'm going to have memory addressing issues or need to do some soldering? Sorry for the dumb questions

 

due to the way DRAMs are multiplexed, there is only one extra address line, which is pin 1, just ground pin one and it in effect becomes a 64k DRAMS... i cant remember if they are tied together in 800XL's (in 130XE's they are not, in the base ram or ext ram), i would have to look at one...

 

sloopy.