A little bit of 8 Bit: 65XE upgrade to 128k RAM

[tfhh]

Hello everybody! i found this great thread about 65XE ram upgrade, but just discovered mine has a 130XE(64x4) motherboard with unpopulated U11, U12 and U35: since aren't more available on ebay the C25953, is there a way to program a GAL for replacing it?

It´s not so easy to expand this XE mainboard. I would strongly suggest to take a more modern expansion. For power users the Ultimate 1 MB is a good choice (availible at Lotharek) or for example my 512 KB SRAM expansion. If you want to DIY, then take this: Hias SRAM expansion. Depends on what you want and how much money you will spend

[rubber_jonnie]

I have the sdrive max, that I use with 65xe and with my 800xl, but I think I'll upgrade only the 65, because the 800 is boxed and I take it out from its polys rarely, to preserve them!
I'm very interested in VB/XE too, I use RGBtoHDMI for most of my retrocomputer, and I am waiting for the OSSC+koryuu i bought some days ago for digitalizing the composite output of the Atari's ones, but if it won't work as expected, I'll go for the VB/XE solution too!

Neither of mine are boxed, though with the 800XL I was careful when doing the VBXL upgrade to make sure that the case was not altered in any way at all as it's otherwise original, and of course I kept the parts so it can be reverted.

I did modify the case on the 65XE so I could retain the monitor port, and since the modulator was long gone (Never worked well and eventually died) I expanded that hole and put the VBXE connector there, which is a 13 pin connector like that of the ST.

The cable I have is SCART, but it works just fine with my OSSC to HDMI. I do tend to plug direct to TV though as it has SCART anyway, and I use the OSSC for my other stuff.

[aotta]

Thank you all for the hints, i've ordered the Ultimate 1Mb and going to desolder the CPU and MMU.
I'll keep the RF modulator since it works fine, and all 65XE's motherboard is in good condition, while the case has some damages, so i'll not worry if i'll have to drill it for a connector if i'd decide to add the VB/XE addon.

[rubber_jonnie]

Thank you all for the hints, i've ordered the Ultimate 1Mb and going to desolder the CPU and MMU.
I'll keep the RF modulator since it works fine, and all 65XE's motherboard is in good condition, while the case has some damages, so i'll not worry if i'll have to drill it for a connector if i'd decide to add the VB/XE addon.

If you're going to keep the modulator, simply remove the original 5 pin connector for the monitor and fit the 13 pin in it's place. Dimensionally it's pretty identical apart from 13 pins instead of 5.

I simply lay the 13 pin connector on it's side once wired up to VBXE and then hot glued it in place on it's side. Doing this means no damage to the mainboard in case you want to go back to the original setup.

This is the socket on my XE:

Video_socket.jpg (66.62 KiB) Viewed 968 times

And you could simply do the same as I've done at the modulator hole at the monitor port to it's left.

And here is the modified modulator hole:

Resized_Modulator_Hole.jpg (66.57 KiB) Viewed 968 times

And how it looks on my 800XL:

800XL_VBXL_Output.jpg (73.17 KiB) Viewed 968 times

Obviously because of the connector key it means rotating the plug 90 degrees to plug in, but once in, you won't notice, especially if you have a permanent setup.

[Trollbra]

Hoping nobody minds, especially since we are predominantly 16 Bit, but having just completed a successful upgrade of my 65XE from 64k to 128k, I know how difficult it was to source the parts, so I wanted to share with everybody.
.........

Mine worked first time, but if it doesn't work for you, I suggest a magnifying glass to make sure there are no solder whiskers bridging pads, and that all the chips are nicely seated.

If it doesn't work first time, provided you've used sockets, then you can remove the chips and check it's all good without.

Hi,

I followed steps but that doesn't work for me. It's strange, 128k games start with graphics glitch (see video below) but no problems with 64k games !



My motherboard :

201219123411453933.jpg (406.05 KiB) Viewed 309 times

PS. RAMs and OS Rom checked with SYS-Check, no problem.


Thanks.

[rubber_jonnie]

Have you definitely checked the upper 64K bank and not just the original lower bank?

If you can you may want to move the RAM chips around, see if that changes the problem. You could also try getting a tester for the RAM.

If I'm honest, the fault is not at all clear from that video, you might be better off with some static screenshots, and you may want to get some static shots of the upgrade.

I'd suggest that you might want to recheck all the soldering, check all the chips have power and check the address, chip select, data in/out lines etc to make sure they are doing as expected.

What is that game by the way, it looks cool.

[Trollbra]

Have you definitely checked the upper 64K bank and not just the original lower bank?

If you can you may want to move the RAM chips around, see if that changes the problem. You could also try getting a tester for the RAM.

If I'm honest, the fault is not at all clear from that video, you might be better off with some static screenshots, and you may want to get some static shots of the upgrade.

I'd suggest that you might want to recheck all the soldering, check all the chips have power and check the address, chip select, data in/out lines etc to make sure they are doing as expected.

What is that game by the way, it looks cool.

The game is Crownland : http://a8.fandal.cz/games.php?name=C&bu ... =&from=250

I check 64k and 128 bank with Sys-Check cartridge, it's ok !

128k games screenshots :

Desert Falcon

1.jpg (75.65 KiB) Viewed 319 times

Mario Bros XE

2.jpg (116.73 KiB) Viewed 319 times

Crownland

3.jpg (148.41 KiB) Viewed 319 times

Solderings

4.JPG (391.66 KiB) Viewed 319 times

5.JPG (70.22 KiB) Viewed 319 times

[exxos]

@Trollbra can you please upload images instead of not linking them to other sites. If your not sure how to do this, then please see the pinned topic on how to attach images, thanks

[rubber_jonnie]

I can't see anything obvious from the soldering, but the picture isn't the sharpest.

If the RAM checks OK with a diagnostic cartridge all I can suggest is:

1. Go over all the soldering with a magnifying glass or microscope to ensure there are no solder whiskers.
2. Swap the positions of the RAM chips, see if the problem moves/changes.
3. If you can test the chips individually, do so.

Unfortunately my XE has since had an upgrade to Ultimate 1MB so I can't compare with mine.

I'm assuming the game program is in the 1st bank, and graphical data is contained in the second 64k bank and mapped in, so whatever is being loaded there is getting corrupted. Or if it needs to be unpacked in some way, is being corrupted then.

It could be that you have a faulty MMU too, I don't know if you have a spare available to try

I'm not really an expert on the inner workings, @tfhh or @guus.assmann may be able to offer more specific help.

[rubber_jonnie]

@Trollbra can you please upload images instead of not linking them to other sites. If your not sure how to do this, then please see the pinned topic on how to attach images, thanks

In addition to uploading the images to the forum, if you could also ensure the orientation is correct before upload as well please.