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1088XEL Alternative Mother-Board Project


mytek

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Now that I looked through assortment of original Atari ICs (I knew one day the Ebay pickup would be useful one day), I did count 2 of each the necessary ICs except for single PIA.

So I'm ready for the XEL :-D

Edited by JoSch
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Another minor fix that I did today had to do with the power-up reset circuit. Since I have the the dual 556 timer in an always powered state so that it can switch on main power through the MosFet, this inadvertently disabled the timer circuit that would hold the reset line low for a moment each time power came on. But luckily the fix for this was also relatively easy, only requiring pin 4 (RST) of the Reset Timer to be jumpered over to output (pin 9) of the 2nd Timer that handles the On/Off switch action. So now each time the switch is momentarily pressed the main power toggles on or off same as before, but if the system is powering ON, the Reset Timer comes up momentarily with it's output (System Reset) in a low state. This insures that everything initializes to the same state.

 

New Circuit...

 

ymQqKBG.jpg

 

- Michael

 

 

P.S. Getting this ready for you JoSch ;)

Edited by mytekcontrols
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One thing that has become painly (intentional pun) obvious with all of my XEL testing is that I need a better joystick ;)

 

I don't want to side track this topic too much, so can someone please link me to a topic that does a good review of all the joysticks, because I really need to get something better to work with... and soon.

 

- Michael

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One thing that has become painly (intentional pun) obvious with all of my XEL testing is that I need a better joystick ;)

 

I don't want to side track this topic too much, so can someone please link me to a topic that does a good review of all the joysticks, because I really need to get something better to work with... and soon.

 

- Michael

 

TAC-2 ... you can thank me later. :)

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Does anyone have a list of all the known ANTIC chip part numbers, including all of the different -xx suffices at the end?

 

These are the two types I currently have...

 

C021697-01

C021697-11

 

Same C021697 part number but different suffices (-01 and -11)

 

The -01's I got from BEST Electronics, and the -11 was in one of my XEGS's. It would be even more interesting if someone knows what the suffix represents (date code?, revision level?).

 

Because I'm very curious as to why the -01 is acting differently then the -11. I have two of the -01's and they both act exactly the same, with neither one liking the PH0 buffering between Antic and the CPU. The -01's without PH0 buffering work quite well across all OS's and applications that I've tested with thus far (OS's: 1200XL, 600/800XL, XE, and XEGS). Whereas I just discovered that the -11 is not quite as flexible, works well under a 1200XL OS, and for the most part does a good job with the other OS's, except in certain instances. Case in point would be what will probably become my main test subject, Galaxian. When booting Galaxian under an XE OS, I get a somewhat scrambled screen and if I recall correctly (I'll have to double check this) an inability to start the game. Works just fine under a 1200XL OS.

 

I'll have to do a comparison in my U1MB equipped XEGS with the -11 (which was where it came from) and see if it has the same problem. If it doesn't then I'll have to try adding the 'AND' gate buffering between the 74HCT138 and the GTIA CS to see what that does in the XEL, since I believe that is incorporated in the XEGS.

 

What I am presently going through while testing out these variations, although a bit annoying, is also at the same time quite fascinating because I'm getting a taste for what Atari Engineers probably went through while developing a given machine in the 8-Bit series. And at this point I am very happy with how the XEL is performing, so even if there are some quirks, at least they'll be defined and able to be worked around. Worse case scenario to obtain best compatibility might require using a chip with a specific part number, such as the C021697-01 for an NTSC system.

 

800px-ANTIC_chip_on_an_Atari_130XE_mothe

 

- Michael

Edited by mytekcontrols
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I have a IMP CO12296-31 pulled from a early 800XL and a AMI CO21697-01 in another 800xl. I'll open up another 800XL and 600XL in the morning to check the models. If you want I can send you the 12296 to test with.

Yogi

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I have a IMP CO12296-31 pulled from a early 800XL and a AMI CO21697-01 in another 800xl. I'll open up another 800XL and 600XL in the morning to check the models. If you want I can send you the 12296 to test with.

Yogi

 

Before you do that, let me check what I have in five 800XL's I picked up a while back for parts. but I'll definitely keep your offer in mind :)

 

- Michael

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Does anyone have a list of all the known ANTIC chip part numbers, including all of the different -xx suffices at the end?

 

These are the two types I currently have...

 

C021697-01

C021697-11

 

Same C021697 part number but different suffices (-01 and -11)

 

The -01's I got from BEST Electronics, and the -11 was in one of my XEGS's. It would be even more interesting if someone knows what the suffix represents (date code?, revision level?).

 

Because I'm very curious as to why the -01 is acting differently then the -11. I have two of the -01's and they both act exactly the same, with neither one liking the PH0 buffering between Antic and the CPU. The -01's without PH0 buffering work quite well across all OS's and applications that I've tested with thus far (OS's: 1200XL, 600/800XL, XE, and XEGS). Whereas I just discovered that the -11 is not quite as flexible, works well under a 1200XL OS, and for the most part does a good job with the other OS's, except in certain instances. Case in point would be what will probably become my main test subject, Galaxian. When booting Galaxian under an XE OS, I get a somewhat scrambled screen and if I recall correctly (I'll have to double check this) an inability to start the game. Works just fine under a 1200XL OS.

 

I'll have to do a comparison in my U1MB equipped XEGS with the -11 (which was where it came from) and see if it has the same problem. If it doesn't then I'll have to try adding the 'AND' gate buffering between the 74HCT138 and the GTIA CS to see what that does in the XEL, since I believe that is incorporated in the XEGS.

 

What I am presently going through while testing out these variations, although a bit annoying, is also at the same time quite fascinating because I'm getting a taste for what Atari Engineers probably went through while developing a given machine in the 8-Bit series. And at this point I am very happy with how the XEL is performing, so even if there are some quirks, at least they'll be defined and able to be worked around. Worse case scenario to obtain best compatibility might require using a chip with a specific part number, such as the C021697-01 for an NTSC system.

I'm only familiar with PAL Antic variants, C014887 (rev. D) and C021698 (rev. E). C014887 features a 7-bit DRAM refresh, which can max. address 4164 DRAMs (128 rows). With this one a 256Kb memory expansion using 41256's requires added circuitry to provide the needed 8th refresh bit. C021698 (later type) has 8-bit refresh built in. My guess is that this version was designed to give flexibility in the choice which DRAMs to build in. The cheaper (and these days infamous) Micron MT4164's needed a 8-bit refresh (256 rows).

IIRC something similar is going on with the NTSC Antic variants (C021696 and C021697).

 

Probably not the answer to your question, and I think you already were aware of this info ;)

 

re-atari

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I'm only familiar with PAL Antic variants, C014887 (rev. D) and C021698 (rev. E). C014887 features a 7-bit DRAM refresh, which can max. address 4164 DRAMs (128 rows). With this one a 256Kb memory expansion using 41256's requires added circuitry to provide the needed 8th refresh bit. C021698 (later type) has 8-bit refresh built in. My guess is that this version was designed to give flexibility in the choice which DRAMs to build in. The cheaper (and these days infamous) Micron MT4164's needed a 8-bit refresh (256 rows).

IIRC something similar is going on with the NTSC Antic variants (C021696 and C021697).

 

Probably not the answer to your question, and I think you already were aware of this info ;)

 

re-atari

 

You are right that just like PAL, there were two NTSC variants as well...

 

C012296 'D'

C021697 'E'

 

And likely the -xx suffices have something to do with a batch and/or manufacturer within these variants (only guessing). Since I'm also seeing a variation in operation between two parts having different suffices, due to 'glue' circuit timing differences, the suffixes could be significant. And when I see the variations in this 'glue' logic (as in added or missing buffering) between the different A8 series systems, it makes me wonder if some of that was being done to tailor operation specific to a given batch. Probably not the case, but it does make me wonder. Anyway it'll be fun exploring what's being used in the seven 800XL's I have in my collection :)

 

- Michael

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I found two more variations in ANTIC chips in just 2 of the 800XL's I opened up today.

 

C012296D-03 (earlier 'D' version chip)

C021697-31

 

So I tested these as well as the ones I already had in the XEGS with a U1MB installed, and Galaxian.atr as my tester via SIO2PC-USB. And all of them acted exactly the same, working fine under a 1200XL OS, but locking up with a 600/800XL, XE, or XEGS OS.

 

Locks up after displaying this image...

 

v5fdKJu.jpg

 

 

And although I thought Galaxian would work under an XE OS on the XEL, I must have been mistaken because it too exhibits the exact same behavior with all of the ANTIC chips I have. Just for grins I also bypassed the buffering between the 74LS138 and GTIA CS on my XEGS and saw no difference.

 

Now for the interesting part... I brought the Side Loader back up, and tried all the versions of Galaxian that were on the CF I purchased with my SIDE2 from Lotharek. All of them worked flawlessly under any OS I have, including an XE OS. Now unfortunately I don't have a CF card reader that works at my shop (where I'm presently at). so I can't transfer the 'XEX' Galaxian files to my PC, put them in a ATR wrapper, and load them back in via SIO2PC-USB. At some point I will do this to see if it's my version of Galaxian that is causing problems, or loading in from the SIO2PC-USB that is the issue. here's the file I'm using if anyone wants to test this out under an XE OS: Galaxian.atr

 

So it would appear that the XEL with only PH2 buffering, is working as well as my XEGS :thumbsup::)

 

- Michael

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At some point I will do this to see if it's my version of Galaxian that is causing problems, or loading in from the SIO2PC-USB that is the issue. here's the file I'm using if anyone wants to test this out under an XE OS: attachicon.gifGalaxian.atr

 

So it would appear that the XEL with only PH2 buffering, is working as well as my XEGS :thumbsup: :)

 

- Michael

 

I just tested your Galaxian .atr (which is a k-file conversion like so many throughout the years). Works just fine on my U1MB-equipped 800XL using an XL OS, an XE OS, an XEGS OS and even OS B.

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I just tested your Galaxian .atr (which is a k-file conversion like so many throughout the years). Works just fine on my U1MB-equipped 800XL using an XL OS.

 

Thank you for doing that :)

 

Gives me something to use as a reference.

 

- Michael

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Ah, you caught me before the edit - I also tested XE, XEGS and OS B. It boots up and plays on all of them for me.

 

Sorry about that ;)

 

After thinking about this for a bit, I remember setting the SIO2PC-USB divisor to '0' yesterday, but likely didn't do that until sometime towards the end of my testing session. Since the loading method for Galaxion that failed was via SIO2PC, I went back in and incremented the divisor up by 1 until it started working (with the end result being 2). So although a divisor setting of 0 worked for most things, loading Galaxion pushed it over the edge.

 

So with that done, I went on to retest the 4 different ANTIC chips I have in the XEL under all 4 OS's I currently have in my U1MB (1200XL, 600/800XL, XE, and XEGS). I'm glad to say any combination is now working just fine :)

 

DrVenkman can I ask you a favor, and have you upload your version of OSB that you are using in your U1MB?

 

- Michael

Edited by mytekcontrols
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I'll test that Galaxian ATR on my NTSC 130XE as soon as I finish up dinner.

 

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

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Got it - thanks :)

 

As expected this OS also works at loading Galaxion into my XEL - no problem.

 

- Michael

Great news!

 

I realized after I uploaded that one that I have two "padded out" OS B roms. One is the unmodified other than the file size (filled out to 16K). The other, I used a hex editor to customize the Memo Pad message. After I uploaded I realized I don't know which version I gave you. So if the Memo Pad message isn't the standard ... Oops. :)

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Great news!

 

I realized after I uploaded that one that I have two "padded out" OS B roms. One is the unmodified other than the file size (filled out to 16K). The other, I used a hex editor to customize the Memo Pad message. After I uploaded I realized I don't know which version I gave you. So if the Memo Pad message isn't the standard ... Oops. :)

 

It's been so long since I booted up into this older OS but it looks good to me "ATARI COMPUTER - MEMO PAD".

 

- Michael

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Glad to see you stomped that bug :) Just a note that may be of interest to builders, I noticed that Best Electronics has both the older CO12296 and the CO21697 ANTICs, but the older is $5 and the newer is $10. Seeing as both these ANTICs are functional equal in the XEL, it would be a point to shave some of the cost.

Yogi

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