Swapping ANTIC in NTSC to run PAL software, using Lumacode

[dabone]

I've got NTSC ataris (800xl and 130xe), and I'm wanting to run pal only software.

 

I've got lumacode out for the video, so I don't have to worry about PAL color encoding, but do I have to swap both the antic and gtia? Or is one mainly responsible for pal/ntsc?

 

 

[Beeblebrox]

I think in that instance you can get away with just swapping out the antic for a pal antic. 

 

However, and it may not be an issue with LumaCode, but I am not sure if you still need the colour burst crystal and pal system clock crystals. You would do normally when converting ntsc to pal on Atari XL and XE machines. I am not sure if the lumacode/gtiadigitizer has these onboard. 

[dabone]

I just ordered a new antic and I'll try from there. 

I also found this site about the os rom hack.

 

https://www.myatari.com/nirdary.html

 

 

[Rybags]

The XL OS deals with PAL/NTSC OK but relies on GTIA to detect what system is in use.

The main things that are different are the key repeat and bitrate settings for cassette operations.

The cassette stuff shouldn't matter if the main crystal isn't changed, and in theory doesn't matter anyway because the overall differences are slight and Pokey can compensate.

The key rate - PAL on NTSC settings will be annoyingly slow.

There might be software that doesn't work properly on a system modded to PAL but retaining NTSC Antic but it would probably be fairly rare.

Edited December 5, 2023 by Rybags

[dabone]

Ok, I got the Antic, and did the bios mod, and no this mod is not worth it.

 

The system will run more PAL software, but, the timing is off for the lumacode board causing screen artifacts, and quite a bit of PAL software still won't run because of the NTSC gtia and crystal combo.

 

I did order a PAL GTIA and crystal from best, and will follow up on the conversion after I get them.

 

[dabone]

Ok, to convert a NTSC 800xl to Pal with full color hdmi out you need the following.

 

These are from Best, using their pricing.

 

CO21698      (PAL XL / XE ANTIC)    $24.95
CO14889-01    (PAL GTIA)            $20.00
CO16112        (3.546894 MHz XTAL)    $2.50

 

Then you need a Raspberry Pi Zero with headers. ($16.00 from adafruit.)

 

Then from Copperdragons Tindie store.

 

GTIAdigitizer $39.00

RGBtoHDMI Mono & LumaCode $40.00

 

So, not the cheapest project, but it does look nice.

I'm around $160 to $170 after shipping, plus the actual 800XL.

 

If you use the lumacode for other units like I do, then the $56 for rgb2hdmi and pi get split on other machines also.

(I'm using it with my C128, ZX81, c64)

 

 

 

Edited December 19, 2023 by dabone

[Beeblebrox]

@dabone ah, so you don't need the pal colourburst C016801 for this ntsc to pal conversion it seems when using lumacode, etc. Makes sense. 

 

Getting the pal sys clock crystal (C016112) over here in the UK is tricky as there are no modern equivalents, unlike colourburst. 

 

You can get them by salvaging one from an old Atari 2600 Junior console, or of course from other donor a8s. 

 

 

Edited December 19, 2023 by Beeblebrox

[woj]

I have a reverse question - on a Sophia2 + VBXE equipped machine, all it takes to convert one from PAL to NTSC is to replace ANTIC with the NTSC one and get rid of the PAL clock circuitry, doesn't it? The main clock is provided by VBXE, so no need to replace the main crystal, correct?

[Beeblebrox]

30 minutes ago, woj said:

I have a reverse question - on a Sophia2 + VBXE equipped machine, all it takes to convert one from PAL to NTSC is to replace ANTIC with the NTSC one and get rid of the PAL clock circuitry, doesn't it? The main clock is provided by VBXE, so no need to replace the main crystal, correct?

yes, correct afaik.

[Rybags]

The modern day VBXE has 2 crystals so yes, you shouldn't need another if doing a standard change.

Mine is an older one so I had to source my own.

What are you going to do with GTIA though?  In theory if you feed it from the NTSC Antic it should generate video with PAL colourburst encoding and work OK on some devices.

If you swap in an NTSC GTIA - I'm not sure what you should do with the PAL pin that otherwise gets the colourburst - possibly it's just NC on that chip.

[woj]

The PAL pin of GTIA indeed seems to be the question, not really sure what it does or which direction it goes, even though I did read the posts around here a bit. Following the schematics recipe (BTW, it will be my 800XL that will undergo this surgery), it should be simple enough just to remove the PAL clock circuitry and bridge W2 (the bridge suggests that even NTSC GTIA needs something on the PAL pin), apart from sticking in the NTSC Antic. I will be using Sophia2 in any case, which should be both PAL and NTSC friendly, I just wonder what is the minimal mod required to get this going, can I, for example, just socket the 74S74 chip and remove it when needed bridging W2 at the same time. Perhaps @Simius can shed some light on how to do this with minimal effort (= make VBXE + Sophia 2 machine go from PAL to NTSC).

 

EDIT: According to my very limited knowledge of circuits, the minimum I'd have to do is to socket / remove 74LS74 and lift both R72 and R73 to cut the power feed to the PAL circuitry. (EDIT2: and of course change the PAL/NTSC jumper on VBXE). 

Edited January 8 by woj

[Rybags]

It's an input and needed because the PAL colourburst doesn't have the direct ratio to system clock as on NTSC (which is 2:1 vs PAL at 5:2)

[Simius]

Sophia doesn't need any signal on pin 16 regardless of PAL or NTSC. The only things it need is a proper ANTIC and system crystal. 74LS74 and 4.43M crystal may or may not be present. It does not matter. 

[woj]

36 minutes ago, Simius said:

Sophia doesn't need any signal on pin 16 regardless of PAL or NTSC. The only things it need is a proper ANTIC and system crystal. 74LS74 and 4.43M crystal may or may not be present. It does not matter. 

So I can leave all the PAL circuitry in place, do not touch it, just plug in NTSC ANTIC and switch the clock on VBXE, correct? If so, soooo sweet!

[woj]

So, just for the record and completion, on a PAL VBXE system with Sophia 2 I replaced ANTIC with an NTSC one, moved the jumper on VBXE to NTSC and that is it, I have a fully working NTSC system. As a bonus I flashed and made it default the NTSC core onto VBXE, this is also on the edge of trivial, and I finally understood what the whole fuss about these NTSC palettes was 😀 

[sideburn]

I have a PAL XE and I just bought the Lunacode and RGB2HDMI from c0pperdragon. This should work without issue on the pal 65XE correct?

 

Also this is my first PAL machine. Is there a list of PAL specific software and demos for the Atari 8-Bit somewhere?

Edited 14 hours ago by sideburn

[Beeblebrox]

1 hour ago, sideburn said:

I have a PAL XE and I just bought the Lunacode and RGB2HDMI from c0pperdragon. This should work without issue on the pal 65XE correct?

 

Also this is my first PAL machine. Is there a list of PAL specific software and demos for the Atari 8-Bit somewhere?

FJC has done a recent video with regards to GTIA digitiser, etc. Granted it's with an 800XL, but will still be relevant.

Just make sure you've purchased the PIhat as well, which engages with the RBG2HDMI. You have to download software also to pop on the micro sdcard.

 

FYI courtesy of Mytek:

https://forums.atariage.com/topic/353560-c0pperdragon-gtiadigitizer-for-atari-8bit/?do=findComment&comment=5359425

 

 

I installed one in a pal XE earlier this year. Ripped out the RF as it was a test rig and I didn't need AV comp or RF anymore, (the RF modulator is needed for AV comp on an XE, (not so on an XL)). Gave me a nice output, but in the end I popped my Sophia2 in as all self contained. I love the fact I have a spare GTIA from adding Sophia2, (a direct GTIA replacement). Gives me a spare GTIA for other machines I have with dead ones. Also, using Sophia2 means you can convert an NTSC XE or 800XL to a PAL machine, where you only need the sys clock crystal and a PAL antic. 

 

I may pop the GTIAdigizer into an 800XL at some stage.

 

Not sure in respect of a comprehensive list of demos and games which are PAL specific. 

 

A lot of the Polish demos will be PAL only. (So the excellent Rewind demo). Also, some polish games like Albert are PAL only.

 

Just download em and try is my advice.

Edited 13 hours ago by Beeblebrox

[sideburn]

43 minutes ago, Beeblebrox said:

FJC has done a recent video with regards to GTIA digitiser, etc. Granted it's with an 800XL, but will still be relevant.

Just make sure you've purchased the PIhat as well, which engages with the RBG2HDMI. You have to download software also to pop on the micro sdcard.

 

FYI courtesy of Mytek:

https://forums.atariage.com/topic/353560-c0pperdragon-gtiadigitizer-for-atari-8bit/?do=findComment&comment=5359425

 

 

I installed one in a pal XE earlier this year. Ripped out the RF as it was a test rig and I didn't need AV comp or RF anymore, (the RF modulator is needed for AV comp on an XE, (not so on an XL)). Gave me a nice output, but in the end I popped my Sophia2 in as all self contained. I love the fact I have a spare GTIA from adding Sophia2, (a direct GTIA replacement). Gives me a spare GTIA for other machines I have with dead ones. Also, using Sophia2 means you can convert an NTSC XE or 800XL to a PAL machine, where you only need the sys clock crystal and a PAL antic. 

 

I may pop the GTIAdigizer into an 800XL at some stage.

 

Not sure in respect of a comprehensive list of demos and games which are PAL specific. 

 

A lot of the Polish demos will be PAL only. (So the excellent Rewind demo). Also, some polish games like Albert are PAL only.

 

Just download em and try is my advice.

Thanks for the info. This project is an xe to laptop conversion so I think the copperdragon lumicode solution should work out fine. 
 

I just finished this conversion from a 1977 “superboard ii” single board computer to a “portable” : https://osiweb.org/osiforum/viewtopic.php?t=882

 

So this next round should have a lot of improvements and best of all it’ll be an Atari 8 bit with Fujinet built in. Much more useful than the behemoth 70s machine!

Edited 12 hours ago by sideburn

[Beeblebrox]

2 minutes ago, sideburn said:

Thanks for the info. This project is an xe to laptop conversion so I think the copper dragon solution should work out fine. 
 

I just finished this conversion from a 1977 “superboard ii” single board computer to a “portable” : https://osiweb.org/osiforum/viewtopic.php?t=882

 

So this next round should have a lot of improvements and best of all it’ll be an Atari 8 bit with Fujinet built in. Much more useful than the behemoth 70s machine!

wow, just checked out the link!! Seriously cool!!  

[sideburn]

Thanks! I’m exited about doing an xe laptop! Just having a little bit of a slow start getting the motivation to do it all over again. That project was Brutal. 

[Beeblebrox]

21 minutes ago, sideburn said:

Thanks! I’m exited about doing an xe laptop! Just having a little bit of a slow start getting the motivation to do it all over again. That project was Brutal. 

I can imagine.  

[+mytek]

2 hours ago, Beeblebrox said:

FYI courtesy of Mytek:

https://forums.atariage.com/topic/353560-c0pperdragon-gtiadigitizer-for-atari-8bit/?do=findComment&comment=5359425

 

My apologies to COpperdragon for misspelling his name (I left out one 'p'). Did anyone beside myself notice that?

 

I'll have to fix that

[sideburn]

Haha I did not notice 

Edited 9 hours ago by sideburn