Question about an 800XL OS in a 1200XL

[ACML]

If I put a 600/800XL OS in my 1200XL, do I have to replace the MMU? I know the built in BASIC function requires the MMU, but what if I only want the OS still on (2) 28 pin 27C64's? Actually, I'm going to use 27C128's and have the 400/800 OS-B selected with the RF channel 2-3 switch on the back. I'm currently using the 1200XL Rev 11 which is 99% compatible with the 600/800XL OS, but i'm finding a few European titles that won't play nice with the 1200XL rev 11 OS. Why are these titles, mostly Polish, having an issue? I like the ATARI rainbow logo on the 1200XL. I guess they used that space (ATARI logo) for the PBI code in the 800XL OS (my theory anyway).

[Rybags]

Shouldn't be needed if no Basic ROM inside the machine.

 

You could probably work out the issue with the programs by running in Altirra with the 1200XL OS and see where it crashes. Most likely cause would be that they use illegal OS entry points. Often those programs are XL/XE only and lots of people outside the US never had 1200XL exposure so didn't know that it's OS was different.

 

Not sure the exact mapping, but the logo code was replaced by the PBI handler, although I believe they also moved some stuff around which slightly improved compatability with the 400/800 OS, but again the programs with problems there are almost always doing illegal OS calls.

[Gunstar]

Are you sure that the problems with those european titles aren't a PAL/NTSC issue? Lots of euro software won't run on NTSC machines, and about 90% will work, IF a PAL Antic is installed, but not all.

What programs are giving you trouble? I can try them on my 1200XL with a PAL ANTIC and Rev 11 OS to see if they work for me. (I have a 32n1 OS, so I can try other OS too).

Edited October 5, 2011 by Gunstar

[Gunstar]

Sorry if I'm being patronizing to you, ACML, but I know 1200XL's were only sold in the U.S., so they are all NTSC, and many PAL programs won't work becuase of this, not becuase is a 1200 OS. As stated, I have a 1200XL equiped with a PAL ANTIC, which allows many euro games to work that otherwise wouldn't, but some still won't, appararently becuase they check for a PAL OS.

 

On top of that, I also have the 32n1 OS that has all PAL OS's on it, including XL/XE revisions, and even when I choose a PAL OS and have the PAL Antic, there are STILL some stuff that won't work from europe.

I've come across these in euro demos, I think they must also check the GTIA chip. These programs actually stop loading, even with a PAL OS and PAL ANTIC, and show a text message something like this; "this is an NTSC machine this demo requires PAL, upgrade to Pal today!"

This makes me chuckle, since I don't really consider it an "upgrade" since the Atari's resolution is less than either NTSC or PAL, so there's no advantage there I can see, plus you have to put up with the flickering 50hz display. It's a necessity for PAL programs, not an "upgrade."

 

I heard someone also installed a PAL GTIA chip to get past that problem, although I can't verify that, though if it works, I'll do it.

Edited October 5, 2011 by Gunstar

[flashjazzcat]

This makes me chuckle, since I don't really consider it an "upgrade" since the Atari's resolution is less than either NTSC or PAL, so there's no advantage there I can see, plus you have to put up with the flickering 50hz display. It's a necessity for PAL programs, not an "upgrade."

When it comes to demos and games, the extra VBL cycles of a PAL machine make a difference. For that reason (from a coding point of view) I regard PAL as advantageous in some ways, although the overall advantage in processing speed is entirely negligible. Is the flicker caused by using PAL Antic with NTSC monitors? It's not something I've witnessed.

 

I heard someone also installed a PAL GTIA chip to get past that problem, although I can't verify that, though if it works, I'll do it.

I have a PAL Antic and GTIA in a 1200XL, but without a VBXE (whose RGB output does not need adjustment), a second osciallator is required to drive the PAL colour circuit. I think a professionally produced board which perhaps sits under the GTIA would be most useful.

Edited October 5, 2011 by flashjazzcat

[Rybags]

PAL is higher resolution, 625 vs 525 lines at the same aspect ratio.

 

CRT TVs and monitors intended for PAL don't flicker.

 

The OS used on the XLs (99.9% sure that includes the 1200) is universal, there's no unique PAL/NSTC ROMs.

 

Most software if it bothers to check for PAL/NTSC will do so via GTIA, although the Antic version is more important re available cycles per frame but takes a bit more effort to check.

 

Also, I doubt putting the 800 OS on a ROM will work - you'd want to use one of the existing ones that's modified to work on XLs.

[Gunstar]

My point in resloution is that it doesn't matter if it's 525 lines or 625 lines when the Atari's highest resolution is 320x192 (slightly higher on the PAL? but too low to make use of 525 or 625 lines of resolution.

Even when I play PAL games or demos that will work on a straight NTSC 8-bit, I don't lose any resolution, I just adjust the vertical height on my monitor and any PAL overscan graphics that run off my screen are visible.

If your going to be viewing something that actually uses more than the NTSC 525 lines, then the PAL screen has the advantage, but not with an Atari 8-bit (at least in graphic resolution, regardless of internal speed changes of the PAL Atari).

 

I have a Commodore 1084S 50/60hz monitor and there is more flickering with 50Hz than 60Hz. Those who grew up with PAL probably don't notice, but those of us used to 60Hz refresh can most definately tell. Sure, you can get used to it, but so what.

These days, even NTSC 60Hz interlace flicker on a CRT bothers me since I've gotten used to the progressive output on modern TV's and monitors! I even notice the flicker on my at 75Hz on my PC CRT monitor more now! Regardless of the refresh rate, modern LCD, Plasma, etc. don't flicker, and I've gotten used to that.

 

There ARE unique PAL/NTSC roms, I have them on my 32n1 OS! Why I don't know, if your are right about them not being needed, but they definately exist!

Edited October 5, 2011 by Gunstar

[Gunstar]

PAL/NTSC preferences aside, I am also wanting to hack another 1200XL I have with OS and Basic from either a 600 or 800XL. Are there instructions somewhere for this? I've already put in 28-pin sockets. I don't necessarily need basic. But all I really know about this hack is from installation of the APE WARP 32n1 OS upgrade on my other 1200XL. Do I change out the same resisters (W7/8/9 locations for W11/12/13)? How about W6 removal? The APE board also connects a couple wires between MMU and PIA and the 3 wires off the board to locations r23 r15 r59, do I need to worry about any of these connections?

[+rdemming]

There ARE unique PAL/NTSC roms, I have them on my 32n1 OS! Why I don't know, if your are right about them not being needed, but they definately exist!

 

There are different PAL/NTSC versions of the 400/800 OS. But the XL OS is the same for PAL and NTSC.

 

Robert

[flashjazzcat]

PAL/NTSC preferences aside, I am also wanting to hack another 1200XL I have with OS and Basic from either a 600 or 800XL. Are there instructions somewhere for this? I've already put in 28-pin sockets. I don't necessarily need basic. But all I really know about this hack is from installation of the APE WARP 32n1 OS upgrade on my other 1200XL. Do I change out the same resisters (W7/8/9 locations for W11/12/13)? How about W6 removal? The APE board also connects a couple wires between MMU and PIA and the 3 wires off the board to locations r23 r15 r59, do I need to worry about any of these connections?

Bob's instructions are pretty good:

 

http://www.retrobits.net/atari/pbi.shtml

 

I'm assuming the APE WARP's jumpers from PIA are designed to intercept the console keys at bootup. I didn't bother with any of this when I modified my 1200XL. I followed Bob's instructions, the only difference being that I installed Basic on a 28 pin EPROM, so the socket and jumpering were slightly different from Bob's original guide.

 

All the information you require is here:

 

1200XL OS/Basic Mod

[Rybags]

The 32in1 has connection to the SELECT key, the other wires are for GND and RESET (since the unit triggers Reset itself when you exit the menu).

 

You have to put the Select connection otherwise you can't get the startup menu.

 

The PIA connection isn't done for other machines, I'd say that it's only needed on the 1200XL to connect the PB1 pin to the MMU.

[+bob1200xl]

Running a 50hz monitor in a room with 60hz lighting will flicker quite a bit...

 

Bob

 

 

 

PAL is higher resolution, 625 vs 525 lines at the same aspect ratio.

 

CRT TVs and monitors intended for PAL don't flicker.

 

The OS used on the XLs (99.9% sure that includes the 1200) is universal, there's no unique PAL/NSTC ROMs.

 

Most software if it bothers to check for PAL/NTSC will do so via GTIA, although the Antic version is more important re available cycles per frame but takes a bit more effort to check.

 

Also, I doubt putting the 800 OS on a ROM will work - you'd want to use one of the existing ones that's modified to work on XLs.

[+orpheuswaking]

Running a 50hz monitor in a room with 60hz lighting will flicker quite a bit...

 

Bob

 

 

 

PAL is higher resolution, 625 vs 525 lines at the same aspect ratio.

 

CRT TVs and monitors intended for PAL don't flicker.

 

The OS used on the XLs (99.9% sure that includes the 1200) is universal, there's no unique PAL/NSTC ROMs.

 

Most software if it bothers to check for PAL/NTSC will do so via GTIA, although the Antic version is more important re available cycles per frame but takes a bit more effort to check.

 

Also, I doubt putting the 800 OS on a ROM will work - you'd want to use one of the existing ones that's modified to work on XLs.

 

 

That's why you play with the lights out

[Gunstar]

PAL/NTSC preferences aside, I am also wanting to hack another 1200XL I have with OS and Basic from either a 600 or 800XL. Are there instructions somewhere for this? I've already put in 28-pin sockets. I don't necessarily need basic. But all I really know about this hack is from installation of the APE WARP 32n1 OS upgrade on my other 1200XL. Do I change out the same resisters (W7/8/9 locations for W11/12/13)? How about W6 removal? The APE board also connects a couple wires between MMU and PIA and the 3 wires off the board to locations r23 r15 r59, do I need to worry about any of these connections?

Bob's instructions are pretty good:

 

http://www.retrobits...atari/pbi.shtml

 

I'm assuming the APE WARP's jumpers from PIA are designed to intercept the console keys at bootup. I didn't bother with any of this when I modified my 1200XL. I followed Bob's instructions, the only difference being that I installed Basic on a 28 pin EPROM, so the socket and jumpering were slightly different from Bob's original guide.

 

All the information you require is here:

 

1200XL OS/Basic Mod

 

Thank you very much. I wondered why I couldn't locate the mod myself with google, since I wasn't searching for the PBI mod, but OS mod. I overlooked the PBI mod instructions! Not something I'm interested in since I just use SIO2PC and one 1050.

[Gunstar]

Sorry for hijacking your thread ACML, we both happen to be working on the same thing apparently.

 

I have one more question about the OS upgrade. Bob Wooley's instructions refer to W9 jumper instead of W13, is this a mistake, or is it becuase this version is using a 24-pin rev. C basic rom and Guitarman's version is using a 28-pin(?) eprom?

I know the 24-pin rom needs a couple pins bent up and connected elswhere too, where the eprom version has just pin 26 disconnected.

[Gunstar]

Never mind with my question in the last post, I found the answer in a paragraph of Guitarman's instructions I had overlooked previously. Thanks again to flashjazzcat and rybags for their help.