Dead 65XE

[Tezz]

Yep, U34 is rewired on the board

[Tezz]

Ah.. I just looked it up online, the u34 is the CO25953 or a 74LS95 can be reprogrammed in it's place? http://www.atarimax.com/jindroush.atari.org/achemmu.html

 

It seems there was a whole lot more to this then I originally thought..

[re-atari]

Ah.. I just looked it up online, the u34 is the CO25953 or a 74LS95 can be reprogrammed in it's place? http://www.atarimax.com/jindroush.atari.org/achemmu.html

 

It seems there was a whole lot more to this then I originally thought..

Tezz,

 

Apparently you need both chips to upgrade your 65XE to a 130XE via this route. I hate to spoil the party, but this will require quite some effort. You can replace U34 with a PAL16L8 using the JEDEC sourcecode on Jindroush's page, but you need this sourcecode programmed into the chip, and so you need access to (someone with) a PAL-assembler (software) and a PAL programmer (hardware). Besides that, PAL's are nowadays largely replaced with GAL's. They basically do the same trick, but sourcecode for a PAL has to be converted before it can be used in a GAL.

As for the good news, a 74LS95 is a standard off-the-shelf article, that any electronics store should have in stock. It will cost 1 UK Pound at the very most. I can't find any reference to it in the 130XE's schematics, though. Looks like a 74LS95 is only needed if you build in a homemade U34...

 

By and large, I think you'd be better off cannibalizing U34 from your defective 130XE. Be careful though, as there are solderpads for a 20-pin IC but U34 is only a 16-pin type. You have to place the IC lined up toward the left, leaving the 4 extra solderpads on the right open.

 

The 3 resistors (0 Ohm resistors or just plain wires to be more accurate) are indeed wired as in a 800XL F. CAS, A14 and A15 inputs going into U34 are directly routed to it's respective output pins. Exception is CAS for the extended memorybank (U34 pin 10), judging by your photo this is not attached to anything (which is probably the reason why the XE won't start with extended memory present).

 

Instead of PM'ing you, I think you'd be more interested to see the schematics to nearly every Atari 8-bit item at:

 

http://www.dereatari.republika.pl/schematy.htm

 

The ones for the 65XE are there. You can even find schematics for the 1400XL, allthough I don't know how accurate they are.

 

re-atari

Edited March 12, 2007 by re-atari

[Tezz]

Tezz,

 

Apparently you need both chips to upgrade your 65XE to a 130XE via this route. I hate to spoil the party, but this will require quite some effort. You can replace U34 with a PAL16L8 using the JEDEC sourcecode on Jindroush's page, but you need this sourcecode programmed into the chip, and so you need access to (someone with) a PAL-assembler (software) and a PAL programmer (hardware). Besides that, PAL's are nowadays largely replaced with GAL's. They basically do the same trick, but sourcecode for a PAL has to be converted before it can be used in a GAL.

As for the good news, a 74LS95 is a standard off-the-shelf article, that any electronics store should have in stock. It will cost 1 UK Pound at the very most. I can't find any reference to it in the 130XE's schematics, though. Looks like a 74LS95 is only needed if you build in a homemade U34...

 

By and large, I think you'd be better off cannibalizing U34 from your defective 130XE. Be careful though, as there are solderpads for a 20-pin IC but U34 is only a 16-pin type. You have to place the IC lined up toward the left, leaving the 4 extra solderpads on the right open.

 

The 3 resistors (0 Ohm resistors or just plain wires to be more accurate) are indeed wired as in a 800XL F. CAS, A14 and A15 inputs going into U34 are directly routed to it's respective output pins. Exception is CAS for the extended memorybank (U34 pin 10), judging by your photo this is not attached to anything (which is probably the reason why the XE won't start with extended memory present).

 

Instead of PM'ing you, I think you'd be more interested to see the schematics to nearly every Atari 8-bit item at:

 

http://www.dereatari.republika.pl/schematy.htm

 

The ones for the 65XE are there. You can even find schematics for the 1400XL, allthough I don't know how accurate they are.

 

re-atari

Thanks a lot for all that info, it's a great help. I think I'll buy the co25953 from best so that i don't destroy a 130xe (even a faulty one). well i have 3 65xe's to upgrade so i think thats the right thing to do. I read that the custom chip was needed with other 320k upgrades but the guide i was following didn't mention it. It was my mistake not to notice that of course it was not present in the 65xe's 130 board. I assumed Freddie was all that was required and that was there. Oh well, I've learnt a lot in the process. At least all my work so far might be still all ok.

[Tezz]

Ok... I'm now just waiting for the CO25953's to arrive from Best, in the mean time I've been reading up on the various (many) 320k memory upgrade methods online and have found a few discrepancies.

 

This is the document that I was originally following:

130XE/320K Upgrade by Scott Peterson (modified by Tom Harker of ICD 01/25/86)

http://aland.roarvgm.com/mods/5.html

 

But, the document that I find on many sites (it too says "Scott Peterson 320k upgrade") is a very different method?

The 65XE 130XE/320K Upgrade! by Scott Peterson

http://www.atarimax.com/freenet/freenet_ma...warticle.php?32

 

The later document has many more stages to it and another 33ohm resistor required.

 

The question is which is the right (or correct) method here? Is the later a later revision? I understand from reading that certain memory upgrades such as the 576k and 1088k can effect normal 130XE compatability with changes to Antic locations etc. (Some of these higher memory upgrades such as 576k and 1088k can have a switch installed to turn the extra ram on/off but they're not upgrades that I want to do) so anyway, I was thinking that maybe the latter was a revision which corrected compatability issues with what I think is a previous method as that latter document says "you'll have a completely compatible 320k 130XE".

 

** EDIT One thing that I didn't mention was that the latter includes upgrading from a 65XE as well as 130XE so that might partly explain why more steps are required

 

Am I right with all that?

Edited March 13, 2007 by Tezz

[re-atari]

Thanks a lot for all that info, it's a great help. I think I'll buy the co25953 from best so that i don't destroy a 130xe (even a faulty one). well i have 3 65xe's to upgrade so i think thats the right thing to do. I read that the custom chip was needed with other 320k upgrades but the guide i was following didn't mention it. It was my mistake not to notice that of course it was not present in the 65xe's 130 board. I assumed Freddie was all that was required and that was there. Oh well, I've learnt a lot in the process. At least all my work so far might be still all ok.

Tezz,

 

I think ordering the IC in the States may be your safest bet. The IC is said to cost around 10 US$ (not exactly cheap), and you have to take the minimum order amount and shipping cost into consideration. But you might easily spend as much money before you have a programmed PAL/GAL at hand.

 

I've given some extra thought to the XE's startup problem when the 41256's are present. From looking at the schematics, I think you could try the following as a temporary workaround just to check if your soldering or any of the 41256's is at fault (no warranty though ). It basically involves rerouting the CAS-signal going into U34 (pin 6), now not to pin 11 (which leads via R110 to the original memorybank) but instead to pin 10 (leading via R111 to your newly installed DRAM's). Both R110 and 111 are 33 Ohm, and located 1 cm over U34 (the UK did go metric, right?). It's just a matter of swapping one side of one of the zero Ohm resistors and connecting this side to its adjacent solderpad on the right. So you leave the end fitted to pin 6 on the bottom row of the U34 solderpads in place, and desolder the top end and resolder it one pad to the right. If the XE again will not boot and just shows a black screen, you don't have to desolder the original DRAM's but just inactivate them by desoldering one of the sides of R110. If that doesn't work, I'm dead in the water...

 

Do keep me posted about the progress you make. I'm beginning to enjoy this tinkering. Sweet memories of days long gone...

 

re-atari

[Gunstar]

 

Do keep me posted about the progress you make. I'm beginning to enjoy this tinkering. Sweet memories of days long gone...

 

re-atari

Huh, that just struck me as a bit un-nerving becuase Back in the day, I drooled over all the cool hacks and upgrades, but had very little knowledge of electronics, so I installed a couple kits, but I am just finally now (the past few years) really starting to tinker and upgrade these old 8-bits, since I know electronics now. Point is, while you have sweet memories of tinkering, I have sweet memories of gaming, and am doing the tinkering for the first time now. I'm going back and upgrading all my vintage hardware like I wished for 20 years ago...

It's kinda like a person who has all this brilliant library of illustrated classic literature they've looked at and enjoyed for 20 years, but have now learned to read and are finally seeing the full story behind the illustrations. Playing the games is like looking at the picture, but programming and/or hardware hacking is like being able to read the computer and see the whole story behind the games. For the educated, it becomes a lot more fun to tinker and/or program. I find myself adding upgrades and modifications more now than actually using the computer and those upgrades.

Edited March 13, 2007 by Gunstar

[Tezz]

I think ordering the IC in the States may be your safest bet. The IC is said to cost around 10 US$ (not exactly cheap), and you have to take the minimum order amount and shipping cost into consideration. But you might easily spend as much money before you have a programmed PAL/GAL at hand.

 

I've given some extra thought to the XE's startup problem when the 41256's are present. From looking at the schematics, I think you could try the following as a temporary workaround just to check if your soldering or any of the 41256's is at fault (no warranty though ). It basically involves rerouting the CAS-signal going into U34 (pin 6), now not to pin 11 (which leads via R110 to the original memorybank) but instead to pin 10 (leading via R111 to your newly installed DRAM's). Both R110 and 111 are 33 Ohm, and located 1 cm over U34 (the UK did go metric, right?). It's just a matter of swapping one side of one of the zero Ohm resistors and connecting this side to its adjacent solderpad on the right. So you leave the end fitted to pin 6 on the bottom row of the U34 solderpads in place, and desolder the top end and resolder it one pad to the right. If the XE again will not boot and just shows a black screen, you don't have to desolder the original DRAM's but just inactivate them by desoldering one of the sides of R110. If that doesn't work, I'm dead in the water...

 

Do keep me posted about the progress you make. I'm beginning to enjoy this tinkering. Sweet memories of days long gone...

 

re-atari

That's sound like a good idea to check it out. I assume that that should allow the xe to then boot with the new ram still inserted, of course at that stage the extra ram will not be usable without the ic installed. Incidentally I read up earlier and learned today that its actually the missing ic CO25953 that does all the hard work with the memory management rather than "Freddie". But anyway, not to digress, re-routing to test that it boots sounds like a good idea. I only have my pristine untouched 130xe which i bought back in 1989/90 so i didn't want to start pulling that apart. My original 800xl which i bought in 1985 is still here and fully working also. I'm looking foward to moving house in the next few weeks where i have a dedicated room planned for my set-up as I've not been able to set it all up for a long time and have been like most people of late making do using emulation. I made time and space aside last week in the midst of packing to quickly set-up my spare laptop with the sio2pc and one of the 65xe's. I'm looking forward to setting everything up permanently and after all the hardware hacks ... getting back into coding again.

 

Thanks for all the advice. It's very much appreciated

Tezz

 

PS. The UK sure did go metric! in fact it's actually illegal to advertise things in the old imperial messurements here... Crazy huh

[re-atari]

That's sound like a good idea to check it out. I assume that that should allow the xe to then boot with the new ram still inserted, of course at that stage the extra ram will not be usable without the ic installed. Incidentally I read up earlier and learned today that its actually the missing ic CO25953 that does all the hard work with the memory management rather than "Freddie". But anyway, not to digress, re-routing to test that it boots sounds like a good idea. I only have my pristine untouched 130xe which i bought back in 1989/90 so i didn't want to start pulling that apart. My original 800xl which i bought in 1985 is still here and fully working also. I'm looking foward to moving house in the next few weeks where i have a dedicated room planned for my set-up as I've not been able to set it all up for a long time and have been like most people of late making do using emulation. I made time and space aside last week in the midst of packing to quickly set-up my spare laptop with the sio2pc and one of the 65xe's. I'm looking forward to setting everything up permanently and after all the hardware hacks ... getting back into coding again.

 

Thanks for all the advice. It's very much appreciated

Tezz

 

PS. The UK sure did go metric! in fact it's actually illegal to advertise things in the old imperial messurements here... Crazy huh

Tezz,

 

That's correct, in my view the XE should boot if you route CAS to the extended memorybank and disable the original 64K by desoldering R110 on one side. CAS is the only signal that is divided into 2 separate signals (CASMAN and CASBNK), and those are each sent to a different memorybank. All other signals going to the DRAM's are 1-on-1 connections. You can see this clearly in the schematic for the 130XE; I hope you managed to DL what you needed from the Polish website I referred to?

Note however that despite the presence of 256K the XE will only see 64K, as U34 also does a trick to address the extra addressline the 41256's have compared to the 4164's. But, as I said in my earlier post, it should give you an indication whether your soldering is up to scratch or if there's something wrong with the DRAM's. If it boots and shows green blocks in the memorytest, either should be fine.

Of course there is a chance my workaround will not budge, as you are now in effect recreating the earlier situation with the 2 memorybanks filled where the XE did not boot. The only difference is that CAS is now routed to the other memorybank. As I don't have an XE in my collection, I have no way of trying it out to verify that this theory of mine works out in practice. Trial and error...

As for the texts about how to upgrade an XE to 320K, it goes to show once more that a single picture tells more than a thousand words. A picture containing the schematic is badly needed in either of these stories...

 

re-atari

[Tezz]

Update on the 65XE's progress...

 

Much to my surprise, I have now successfully managed to desolder the OS rom, socket it and reinstall the original chip I worked very carefully but even so I didn't expect it to boot first time.. After struggling with it for so long I'm very happy about it.

 

I carefully used a 25w iron and wick to finish the job removing the stubborn soldern that wouldn't shift with my low watt iron.

 

This means I can finally order the 32-in-1 OS!! whoo hoo

 

Next job now though is to add a socket and the CO25953 into the left side of U34 and hopefully then it will see 128k when I repopulate the right bank with my new 41256 ram chips.

 

If all is well with that, I will follow the Scott Peterson mod to make it my target 320k

 

The new XE keyboards arrived last week so with the new paint job, they will also look the part too

[Tezz]

:D

 

Today is a happy day, I finished my 65XE repair/upgrade/restoration. The MMU installation, ram upgrade and OS-ROM socketing was all successful

 

For anyone who's not read this thread before, here's a recap...

 

I wanted to save these from destruction and restore them back to factory condition upgrading them to 320XE's along the way. The first one here, I will be keeping myself and modding further..

 

This 65XE was DOA when I bought it to be rescued. It (along with the other 3 65XE's I bought) had a 130XE motherboard, Atari left out the custom mmu chip and installed with 64k in the left bank.

 

The XE was dismantled and the faulty ram was replaced, the motherboard was jet blasted and throughly cleaned. The outside casing was soaked in hot/warm water with cleaning solution added and scrubbed clean with a small brush, the stubborn marks were removed with spot cleaner and small amounts of household bleech. The case when dry was carefully masked off for painting which was done with grey enamel primer spray 2-3 carefully evenly applied coats. A new keyboard was purchased as the original was very yellow.

 

Inside, I added a socket and installed the CO25953 custom chip into U34 removing the rewiring that Atari installed to bypass the second bank. The right extended ram bank was socketed and 41256 120ns 256k ram chips were installed along with bypass capacitors. I then desoldered the OS ROM and socketed it putting the original ROM back ready for 32-in-1 OS (to be installed next). Happily the GTIA was already socketed on this board.

 

With everthing socketed and 41256 256k ram now installed, the final step will be to do the Scott Peterson 320k mod

 

Here's some photo's.. the finished motherboard, now with socketed GTIA, ram and mmu and the exterior with new keyboard and new paint job (I'll post some before pictures later on)

 

Regards to all,

Tezz

Edited March 31, 2007 by Tezz

[re-atari]

:D

 

Today is a happy day, I finished my 65XE repair/upgrade/restoration. The MMU installation, ram upgrade and OS-ROM socketing was all successful

 

For anyone who's not read this thread before, here's a recap...

 

I wanted to save these from destruction and restore them back to factory condition upgrading them to 320XE's along the way. The first one here, I will be keeping myself and modding further..

 

This 65XE was DOA when I bought it to be rescued. It (along with the other 3 65XE's I bought) had a 130XE motherboard, Atari left out the custom mmu chip and installed with 64k in the left bank.

 

The XE was dismantled and the faulty ram was replaced, the motherboard was jet blasted and throughly cleaned. The outside casing was soaked in hot/warm water with cleaning solution added and scrubbed clean with a small brush, the stubborn marks were removed with spot cleaner and small amounts of household bleech. The case when dry was carefully masked off for painting which was done with grey enamel primer spray 2-3 carefully evenly applied coats. A new keyboard was purchased as the original was very yellow.

 

Inside, I added a socket and installed the CO25953 custom chip into U34 removing the rewiring that Atari installed to bypass the second bank. The right extended ram bank was socketed and 41256 120ns 256k ram chips were installed along with bypass capacitors. I then desoldered the OS ROM and socketed it putting the original ROM back ready for 32-in-1 OS (to be installed next). Happily the GTIA was already socketed on this board.

 

With everthing socketed and 41256 256k ram now installed, the final step will be to do the Scott Peterson 320k mod

 

Here's some photo's.. the finished motherboard, now with socketed GTIA, ram and mmu and the exterior with new keyboard and new paint job (I'll post some before pictures later on)

 

Regards to all,

Tezz

Good to hear the restoration turned out all right; every A8 rescued from the scrapheap is a good result. As a usefull side effect, you have gained invaluable experience in hardware projects (and desoldering in particular ). All tinkerers learned to overcome their fear of possibly ruining something this way. Of course it will not prevent them from inadvertently ruining some component along the way every now and then...

 

re-atari

[+Guitarman]

Of course it will not prevent them from inadvertently ruining some component along the way every now and then...

 

re-atari

 

That's for sure!!!

[Tezz]

Thanks for everyones help, support and advice. It was much appreciated.

 

It's a bit of fear of the unknown with the desoldering. If I damaged the board, that kinda would've defeated the whole purpose of rescuing them so I was extra cautious proceding and learning along the way. I'd advice for others to do it in that way because jumping into something heavy handed without experience is a sure fire way to disaster.

 

I would whole heartedly recomend desoldering wick over using a pump it was way easier and successfull. Most of my struggles were from using an iron at too low a wattage (7w) although it did the job and didn't damage the IC's either.

 

I hope this all helps anyone else wanting to do the same thing and rescue more XL's and XE's.

 

Regards,

Tezz.

Edited March 31, 2007 by Tezz

[hueyjones70]

If I just want to make my 65XE into a 130XE all I need to do is install the sockets in the empty column, fill the sockets with 4164 or equivalent RAM chips and install the CO25953 in the left most slots of U34? I saw a 74LS95 mentioned, where does it go?

On 3/12/2007 at 5:30 PM, Tezz said:

 

 

[+kheller2]

13 minutes ago, hueyjones70 said:

If I just want to make my 65XE into a 130XE all I need to do is install the sockets in the empty column, fill the sockets with 4164 or equivalent RAM chips and install the CO25953 in the left most slots of U34? I saw a 74LS95 mentioned, where does it go?

 

Depends on the 65XE.   NTSC 65XEs w/o expansion port are 900XLFs and not easily converted. 

[Beeblebrox]

@hueyjones70   This might help

 

 

[hueyjones70]

My 65XE has the same MB as the one in this thread except that it is a PAL. Does that make any difference?

[manterola]

I guess that if you have the motherboard marked 130xe(64x4) you just need two 4464 RAM chips and the EMMU (CO25953). 

[hueyjones70]

Mine has 8 4164 RAM chips and 8 empty slots; just like the one in the pictures.

[hueyjones70]

This is totally irrelevant to the current topic but this 65XE that I have has the best stock video that I have ever seen on an A8. No jail bars and crisp well defined characters.