Jump to content
wood_jl

How would you "roll your own" PAL Atari 800 (the Big Beige Beast)

Recommended Posts

First off, apologies if I've asked something of this before, but I didn't see that thread. Once again, apologies.

 

One of the milestones I'd like to pass is to have an original beige Atari 800 run all the cool Euro-demos (Numen, etc). That's not the easiest task.

Obviously, that will require an Incognito. Have that, already.

 

But what about the rest? Options are (all require Incognito installation post-mortem):

 

(1) Import a PAL Atari 800 (complete) from England (or wherever, England being most likely).

 

(2) Swap out boards (motherboard, whatever-else-board(s)) to NTSC machine, thereby making it a PAL machine with real PAL boards.

 

(3) Do meticulous stuff like swap out ROMs, ANTIC, GTIA, whatever crystal(s) are necessary. SPECULATION HERE. Most help and suggestions required with this option.

 

 

Technical Wizards (thank you very much now and whenever you chime in), can you describe what would be necessary to accomplish this? What boards (in entirety) would need to be traded (say, main motherboard and CPU daughter-card) to do this, as opposed to do this with changing ROMs, Antic, and whatever crystal(s)?

 

As usual, thanks so much in advance!

 

Share this post


Link to post
Share on other sites

Board swap probably easiest. Personality (OS) board out of the way first, OS is different between Pal/NTSC although you can use the wrong one, key repeat will be annoyingly slow running Pal OS on NTSC Antic and tape operations will be less precise since the baud rate -> AUDF tables will differ. I should think if everything is socketed then simply swapping out the Roms or burning the PAL E and F OS Roms should be sufficient (D Rom is FP which is universal)

 

CPU board - I've no idea if NTSC boards have provision for adding the second crystal required for Pal colourburst. Might be easier to just swap the entire board over. Adding the Pal crystal if provision isn't there would probably = a little bit of a mess.

 

Power supply - difference is 50 vs 60 Hz incoming 9V AC, I suspect should be the same.

 

RF - probably different as even same standard machines use different seperation between video and audio signals, but hey! You'd want to use a real monitor anyhow.

Share this post


Link to post
Share on other sites

I imported a 800 and converted it to PAL successfully.

 

I did have help where I swopped out a card from a 400 model, swopped a chip from the mainboard (can't remember which but I can digout the details)

Also I transplanted the Crystal as everything was a 5th faster! (Crystal is 2 solder joints only so it's a breeze)

 

incognito was added and have a lovely machine (and a NTSC 400 now!)

 

A uk psu from any unit such as a 400, 800 etc work fine as the dc volt/current requirement is the same going to the atari everything is socketed so it's quite quick.

Edited by Magic Knight

Share this post


Link to post
Share on other sites

I suspect motherboards should be identical or at least functionally fully compatible.

 

Clarification on PS - 400/800 has both the external and internal, external of course is a nobrainer and tends to differ among various countries. Internal stage on those machines is to convert that 9V AC coming in into the DC 5V and 12V used inside.

Share this post


Link to post
Share on other sites

I imported a 800 and converted it to PAL successfully.

 

I did have help where I swopped out a card from a 400 model, swopped a chip from the mainboard (can't remember which but I can digout the details)

Also I transplanted the Crystal as everything was a 5th faster! (Crystal is 2 solder joints only so it's a breeze)

 

incognito was added and have a lovely machine (and a NTSC 400 now!)

 

A uk psu from any unit such as a 400, 800 etc work fine as the dc volt/current requirement is the same going to the atari everything is socketed so it's quite quick.

That would have been the CPU card from the 400, it would contain the PAL ANTIC(CO14887)/GTIA(CO14889), and the PAL OS ROM chips(CO15199/CO15299) from the mainboard.

Share this post


Link to post
Share on other sites

On the main board, The main crystal will need to be swaped.

There is a couple of bits near the video circuit that will also need to be swaped. One is the tall inductor. Cannot remember if anything else needs to be changed. Those bits are for the rf modulator. Swap only is you wish to use a tv.

 

James

Share this post


Link to post
Share on other sites

That would have been the CPU card from the 400, it would contain the PAL ANTIC(CO14887)/GTIA(CO14889), and the PAL OS ROM chips(CO15199/CO15299) from the mainboard.

Aye, It took some days to figure out and google what to do, but if i were to do the conversion again, it would take less than 10 minutes as its really a card, 1 IC from the mainboard and a crystal swop in reality.

 

Also the (uk) 810 PSU can power the 800 as can the uk 400 PSU - i use a few and swop over occasionally without giving a monkeys which im using as they are similar in wattage.

 

getting the ntsc 800 into the uk without paying a fair sum is the more tricky part...

Share this post


Link to post
Share on other sites

All I did to mine was swap out the ANTIC chip for the PAL version and that has worked very well. Most games and demos will now run. Dropzone now plays at the correct speed, and PAL-only games like Marbled, Qb, Assembloids work fine.

 

The only problems I have are with software that tries to detect what flavor machine its running on and adjust itself accordingly. I don't know if it's looking at the OS or the GTIA, but my machine still 'appears' to be NTSC to those titles. The Little Princess demo doesn't run - Ridiculous Reality runs in NTSC mode, as does Yoomp! Pac-Man Arcade detects NTSC and runs painfully slow because it's on a 50Hz machine.

 

One other thing to be aware of is that some PAL games use more scan lines than NTSC and sometimes the very top or bottom of the screen will be cut off - scores, status bars, etc.. I just adjusted the vertical size on my monitor to solve that problem.

 

All in all, I highly recommend this mod.. it's easy, cheap and opens up a whole new continent of titles. Just keep a second NTSC machine stock for when you need it. I don't think anyone has yet come up with a way of installing both chips and having the ability to switch between them.

Share this post


Link to post
Share on other sites

Wow, this might not be as easy as originally imagined! Thanks for all the fine input, so far!

 

 

I had failed to consider the different power requirement, as in the 9V power supply is AC on the 400/800/1200, as opposed to the other XL/XE series, where it's DC and one need only use the power supply corresponding to their local power (the "mains") and there's no other consideration.

 

So the PAL 800 "expects" 9V AC at 50hz, so a 60hz Yankee supply will not do it? So what is needed (assuming such availability) would be a "real" U.K. (or wherever else, non-U.S.) power supply, and a converter to 220v 50hz?

 

This appears more "involved" than I originally imagined. Importing an actual PAL 800 and purchasing a power converter (110V AC/60hz - to 220V/50hz) - if such a beast exists and is affordable, would be a necessity?

 

Thanks again, fellas.

Share this post


Link to post
Share on other sites

I have NFI on the initial DC 9V coming in but essentially you have 2 different waveforms and the RMS voltage going in should be the same. I've run the 1200XL Bob sent me using my 50 Hz PSU for the 1050 and it worked fine.

 

The simple Antic swap - multiple problems including the fact the PAL register resides on GTIA, actual "proper" way to region test is to see how high VCOUNT (Antic) reaches but few programs that care about system do it that way.

 

Additional to that you have the fact that the base clocks are sufficiently different that the line/frame rate will be slightly off spec although frame rate on both systems doesn't match the official spec due to the missing half scanline.

Share this post


Link to post
Share on other sites

All that matters is close to 9V ac at about 2A. A 810/1050 PS will work fine. The 50/60Hz factor doesn't matter in the slighest.

 

James

Share this post


Link to post
Share on other sites

All that matters is close to 9V ac at about 2A. A 810/1050 PS will work fine. The 50/60Hz factor doesn't matter in the slighest.

 

James

I agree - DC is voltage with a stable current where AC alternates the current and the frequency is an issue.

 

A 400 tape recorder would have issues, but the input to a 800 is pure DC by the time its at the plug-in jack stage and US or Europe PSU's can be used pertaining to your territory.

Edited by Magic Knight

Share this post


Link to post
Share on other sites

uk power is about 57hz, so don't worry about that.

for a quick and dirty mod to run the pal demos just put a pal ANTIC in your NTSC 800. I know your jvc bvm will handle the funny video signal

Share this post


Link to post
Share on other sites

NecroBump :)

 

Does anyone know if there are 6502B PAL CPU cards, or are they C014806 Sally type only? I want to make my 800 PAL, but I have an '816 in it, so I need the 6502B style board (if they exist).

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...