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1088XEL Alternative Mother-Board Project


mytek

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Stephen - probably not too urgent at this point, since it looks like the problem really centered around the transfer speed setting for the SIO2PC-USB being a bit too aggressive. But I would be interested to see how far you can push the speed on yours with a stock system.

 

- Michael

I'll let you know. You definitely cannot always rely on PoKey divisor of 0 for all things, that much I know.

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Pajero over at www.atari.org.pl had these concerns after reading some of the latest posts about the timing issues I was having with different Antic chips...

 

 

Mytekcontrols describes ANTIC NTSC different models, they work differently? Is there anything like GTIA bug for ANTIC?

 

To better answer this, it appears that whatever timing issues I was seeing, were mainly related to my use of an 'AND' gate to buffer the PH0 coming from Antic and going into the CPU. This added a delay that apparently was enough to upset some NTSC Antic chips, but not all. Probably having this additional delay in the clock loop put things just on the edge of the acceptable parameters for the Antic chip, with the end result being some chips being more susceptible than others. And this was also strongly influenced by the what the application was doing with PMG's. By removing that PH0 buffer, all Antic chips now appear to work properly (at least all of the different NTSC ones I've tested).

 

The other issue that was not related to Antic, but had me thinking there was a problem, had to do with using Divisor '0' in RespQt for the SIO2PC-USB and with a Hi-Speed OS (provided by FJC's Alt BIOS for the U1MB). So what I found out is that for a few specific applications (games) a higher divisor is required. Hence for Galaxion it looks like nothing below Divisor '2' is recommended.

 

Other than these minor issues (including the reversed address lines on the PIA), the XEL is now looking very solid, and appears to be 100% capable of doing all that a real A8 can do.

 

- Michael

Edited by mytekcontrols
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That Galaxian .ATR image boots and works fine on my Incognito over SIO using divisor zero.

(The k-boot one)

 

Edit: The one from post 464.

 

That's fantastic :thumbsup: And not surprising that some combinations of hardware can do it. But my XEGS U1MB machine can't, and apparently my XEL isn't about to either. The problem is zeroing in on the difference. For me Galaxion is the only game I've come across that won't load properly at Divisor '0'.

 

Kyle thanks for running that test. Now I'll be curious if any U1MB owners can get those same results. BTW, did you remove the caps on your SIO port, because that's even more impressive if you didn't?

 

- Michael

Edited by mytekcontrols
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Yeah the XEL also doesn't use caps on the I/O. Although I got a little over zealous in this aspect and forgot that the paddle inputs absolutely need to have caps in order to perform that crude A/D conversion ;)

 

I think it's highly doubtful that you could use divisor zero on a system that is still capped, but hey you never know.

 

- Michael

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Yeah the XEL also doesn't use caps on the I/O. Although I got a little over zealous in this aspect and forgot that the paddle inputs absolutely need to have caps in order to perform that crude A/D conversion ;)

 

I think it's highly doubtful that you could use divisor zero on a system that is still capped, but hey you never know.

 

My 800XL with U1MB works fine with my SIO2PC-USB devices (based on genuine SparkFun Basic Breakout and those with Chinese clone chips) at divisor Zero. SIO capacitors are present (not touched)

 

madi

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I think it's highly doubtful that you could use divisor zero on a system that is still capped, but hey you never know.

 

I've seen prototype new hardware running on an unmodified 800XL having no problems with divisor zero because they put schmitt-triggers on the serial and clock lines. It even went up to about 250kbps when externally clocked.

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My 800XL with U1MB works fine with my SIO2PC-USB devices (based on genuine SparkFun Basic Breakout and those with Chinese clone chips) at divisor Zero. SIO capacitors are present (not touched)

 

madi

 

Makes me wonder why I can't have success loading in Galaxian with divisor zero when I have no capacitors? Because other than the capacitors being left out, my SIO circuit should be identical to what you have, including the SparkFun board. Maybe I'll put the caps in and see what happens ;)

 

800XL SIO

 

0tjRu1O.png

XEL SIO

OICHVap.png

 

 

Michael, have you tried the SIO FIFO to see if there are different results with Divisor 0?

 

Not yet, but I will.

 

 

I've seen prototype new hardware running on an unmodified 800XL having no problems with divisor zero because they put schmitt-triggers on the serial and clock lines. It even went up to about 250kbps when externally clocked.

 

Yes I could see with the right signal conditioning that the caps would pose no problem for even higher speeds. However this is not something I'll be doing on the XEL, since I'm trying to keep things simple, and for the most part divisor zero works just fine (so far I've loaded about 40 games, a few demos, and some applications with only Galaxian having a problem).

 

- Michael

 

Happy Easter Everyone :)

Easter.jpg

Edited by mytekcontrols
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\O/ And we have boot! Despite a few expected teething pains, it's coming together exceptionally well. :D

 

I keep looking at this and the developing 1090-alike project and glancing over at my non-functional 800 and I have these strange schemes that keep popping into my head, even though I have little of the talent to pursue them outside of fever dreams. ;) Both of these boards might be fittable within an 800 case. I wonder who might be the first to scheme to rework and retrofit the card slots in the back of the 800 to be PBI slots instead, with the boards that originally occupying those slots now being incorporated into the main-board, using this project as a base..... In effect creating something that would never be, but many had hoped for - all fitting within original case-work.

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\O/ And we have boot! Despite a few expected teething pains, it's coming together exceptionally well. :D

 

I keep looking at this and the developing 1090-alike project and glancing over at my non-functional 800 and I have these strange schemes that keep popping into my head, even though I have little of the talent to pursue them outside of fever dreams. ;) Both of these boards might be fittable within an 800 case. I wonder who might be the first to scheme to rework and retrofit the card slots in the back of the 800 to be PBI slots instead, with the boards that originally occupying those slots now being incorporated into the main-board, using this project as a base..... In effect creating something that would never be, but many had hoped for - all fitting within original case-work.

I like this idea, and out of all the thoughts about putting the XEL into an original Atari case this one actually makes a lot of sense to me. But to do it right, it really needs to be done in another form factor as you are suggesting. This would be an equally monumental task as the XEL has already been, and not something I will be taking on. However I'm not opposed to someone else doing this based on anything found of use in my XEL design. And as such when this project releases Summer of this year, the schematics and PCB design files for the XEL will be a part of that creative commons release package.

 

Now some people may be put off by my choice of design software, and the fact that it is in a file format that is not easily imported into various other 'open' PCB layout programs. But please keep in mind that the XEL project started out as a personal project, and then transitioned into something to be shared. And by the time that decision was made, I was in way too deep to start over from scratch. However in the spirit of cooperation I propose that for anyone that seriously wants to take on this 'new' project and see it through, I would be willing to use the ExpressPCB to Gerber 3rd party conversion software I purchased to convert any ExpressPCB files sent to me for this project, and this project only. Since the ExpressPCB software is freely available for download and use, my offer should remove any barrier to modifying the XEL files and morph it into a new design. All I ask in return is to respect the choices I made in regards to what tools I decided to use in my XEL project, and the choices I have made pertaining to how this information was and/or will be disseminated. I also ask that people respect my time, and that only individuals with serious intentions take me up on my offer.

 

With that said, I do look forward to seeing what other people decide to do with what I have created in the XEL project, and how pieces of that might find their way into other projects to come.

 

- Michael

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Hello Michael.Can you be so kind and make some POKEY tests?Mono/Stereo songs?RMT player or tmc,mpt or sap...And make video?I will post it on Chipmusic.Org...

 

I think form factor is perfect.There are 1000s of miniITX cases.Lot of are beautiful.Also one can buy not working Atari ST for price of coffee latte. I have buyed 2x defunct STFM for 30euro... So you will have 130xe look, design...And room for XEL and also lot of room for something else /x86 mini itx board for example/.

Edited by Matej
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Hello Michael.Can you be so kind and make some POKEY tests?Mono/Stereo songs?RMT player or tmc,mpt or sap...And make video?I will post it on Chipmusic.Org...

I'll try to do that, but it's going to be low on my 'to do' list, since I will be busy getting stuff ready to send to my beta testers, and still have some other tests that are a much higher priority. For now I can assure you that it works in the same way as the TK-II-Stereo board does.

 

- Michael

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I posted some infos about 1088XEL on Chipmusic.Org http://chipmusic.org/forums/topic/19600/2x-new-miniitx-8bit-ataris-in-dev/ so your board will have more fans...

 

Matej thank you for writing such a nice introduction of both the XEL and the EclairéXL projects :thumbsup: :)

 

As the XEL prototype enters into it's final testing phase, it's looking pretty solid and other than a few minor fixes that will be incorporated into the final board release, a Summer 2017 release into the wild is imminent. So for those that are interested in building their own, buying a complete kit, or possibly even purchasing a fully assembled board we are within a few months of seeing that happen.

 

Some people have been concerned about the cost, but keep in mind a pretty good chunk of that is because of the required Atari LSI chips having gone up in price over the years. If you can source those chips from an old A8 that you no longer use, the cost drops by $60. If you already have a U1MB and have the skills to desolder the headers and replace them with vertical ones (or know someone that does), you can knock an additional $60 off the total cost.

 

Looking at it from a modular standpoint the cost breakdown goes something like this...

  1. $75 --- XEL board and all discrete components (minus Atari LSI chips and the other items listed below)
  2. $60 --- CPU, ANTIC, GTIA, PIA, POKEY(x2)
  3. $60 --- U1MB
  4. $25 --- UAV
  5. $15 --- SparkFun BOB-12731 (SIO2PC-USB)

Note: This is only the cost of parts and does not include assembly labor and shipping. The XEL board cost is predicated on a minimum build of 10 pieces.

 

So in the grand scheme of things, the XEL board by itself is not that costly. But yes you will need most all of that other stuff to make a complete working system. However some things can be left out initially, such as the 2nd POKEY or the SparkFun board. And as I already pointed out some items like the Atari chips can be recycled from older unused equipment. And obviously if you are skilled enough to assemble your own, there will be no labor costs added.

 

After next week, I'll try to get some more demo videos posted showing off the various aspects.

 

- Michael

Edited by mytekcontrols
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Will there be tests with VBXE and/or Rapidus?

 

Yes. But that will be done by members of the BETA Test Group I assembled (Stephen for one), who will be getting their boards next week. I don't personally have either one of those boards, otherwise I'd participate in this testing as well. And both of those boards are a bit expensive (especially Rapidus at almost $200), and I already have just a little over $1,000 invested into this project as it is (all non-refundable R&D). So it just wasn't in my budget unfortunately. Although the other people that will be testing the XEL with these upgrades, are much more likely to know what things to do in order to give it a good shake-down. I'm really more of a hardware guy myself, and would be reliant on software that other people wrote to do this.

 

- Michael

Edited by mytekcontrols
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I have 2x not working A130xe so some parts will be there.As I live near Lotharek I will buy Ultimates from Him (I meet Him at EU Atari partys).So I will take 2x minimal kit. Another question is will XEL support VBXE or SOPHIA? As one of mine A130xe spare board got wrong gtia (only b/w colors...).For me price is good.And I have 20x Pokey at home so Pokeys are not problem.As I am CAD designer I will do 3d printed case for me.Inspired from XEGS or MegaST...I will opensource files than.

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I have 2x not working A130xe so some parts will be there.As I live near Lotharek I will buy Ultimates from Him (I meet Him at EU Atari partys).So I will take 2x minimal kit. Another question is will XEL support VBXE or SOPHIA? As one of mine A130xe spare board got wrong gtia (only b/w colors...).For me price is good.And I have 20x Pokey at home so Pokeys are not problem.As I am CAD designer I will do 3d printed case for me.Inspired from XEGS or MegaST...I will opensource files than.

 

Sophia is no problem, and I have one mounted and running already on my XEL version 1.0 board (I'll take a picture and post it soon). The VBXE should also work and there looks to be enough room to do so, as well as required signals at the MPBI connector.

 

Wow 20 POKEY chips :-o those would be worth a lot on today's market.

 

I will enjoy seeing what kind of case(s) you create :)

 

- Michael

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Sophia in XEL

 

That is the stock cable that Simius sent with the Sophia, except for the additional 10 pin IDC connector added by me for RGB/YPbPr-THRU to DIN-13 (ST Monitor Compatible) rear panel connector. Either the stock D-Sub 9 or the DIN-13 can be used for monitor connection.

 

CVgXooY.jpg

 

XEL/Sophia Component Output

 

Go8VFh0.jpg

 

 

- Michael

Edited by mytekcontrols
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I spoke with Lotharek a few weeks ago about the possibility of getting U1MB boards already stuffed with all vertical instead of right-angle headers and he seemed open to the idea, but more negotiation will be required to firm this up.

 

csYzmHH.jpg

 

I can't fully describe what a great feeling it is to simply plug this into the XEL without fussing with ribbon cables and mounting screws. And due to the R&D nature of the first run boards, I have had to remove and replace this numerous times, with each time bringing a smile to my face :)

 

- Michael

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