Tubular Gearhead
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Posts posted by Tubular Gearhead
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With all due respect, having this thread in the A8 and the 7800 forums seems like an attempt to provoke a cross-forum flame war. As I wrote in the 7800 forum as well, how about we all take a deep ole' breath and spend the afternoon playing fun games on our 7800s and A8's?
+1 I second the motion. I have both, love both, play both.
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Wow, that is really neat looking. I for one would love to play this hi-res version, even with the limited colors. I know it is easy for others to say when they aren't the ones doing the coding, but I hope you continue with this project...
It is great to see all the activity on the 7800 front as of late.
Good job!
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though given the system already specifically differentiated between modes on the software side, such a mechanism might not have been useful -unless it was cheaper/simpler than using MARIA/7800 booting to toggle the video)It differentiates in hardware too. When Pin 5 on the LS174 (U11 on the NTSC schematic) is low then MARIA is disabled. When pin 2 of U11 goes high the video mode is "locked".
If MARIA is disabled you can enable your own 2600 AV mod. After the 7800's BIOS has determined the cart type and its found to be a 2600 one then the video mode is "locked" so that 2600 games can't change it back.
Ok, so this got me thinking and looking at the schematic again to try and remember what exactly I did. If you look at U3 (logic gate) you will see that the 2600 and 7800 Luma and Sync signals are indeed switched. The Chroma signals, however, are not. Specifically, the value of R17 has been chosen high so the 2600 signal will not override the 7800 signal causing interference when MARIA is enabled. So, at the very least, R16 and R17 should be replaced with pots and switched before combining @ L1. This would be a good spot for another logic gate (I think that is where I used the old channel switch). If I remember right, I also reduced the values of R11, 12, 13, & 15 by about half, preserving the spread of the Luma logic ladder (is that what it is called?), but making it easier to amplify w/o adding additional stages. I am pretty sure I just used only one transistor. I changed the value of R10, but I am not sure if I added a diode to the Sync or not- I think it was better w/o one. I don't think it was necessary to amplify the Sync. I will try and take some photos of the mod and draw up a schematic at some later time.
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That's correct. It's in the circuit which feeds the rf modulator. Basically, I think the specifications were for somebody to be able to just plug in any cartridge, be it 2600 or 7800, and have the machine play it w/o the person having to slide a switch putting the video circuit in the correct mode. As you said, it could have been done automatically (digitally, MARIA takes over when a 7800 cartridge is plugged in, but the analog signals stay blended), but I guess it was cheaper to just mix all the signals, and work with the values and levels until the compromise was acceptable (although as pointed out, it is noticeable and I don't consider it acceptable).
Couldn't they have used a digital switch (triggered either by booting in 7800 mode or a physical signal on the cart slot) that toggled between MARIA and TIA composite output -only ever connecting one analog video signal at a time? (in the case of a dedicated cart signal, that would eat up one of the few added cart pins... unless maybe they could hack one of the existing VCS pins for such: assuming shield-ground was properly grounded on every single VCS game released, they could pull it high to toggle to MARIA video and at the normal grounded state for VCS -though given the system already specifically differentiated between modes on the software side, such a mechanism might not have been useful -unless it was cheaper/simpler than using MARIA/7800 booting to toggle the video)
Hell, even with a manual switch, they could have left it convenient for the layman (or lazy people who didn't care about color/video quality) and had a mixed setting by default with an on/on/on switch toggling from TIA to both to MARIA with the factory default set to mixed to be fairly foolproof and still avoid any added logic for automatic switching.
Yes they could have. I don't know why they didn't- usual 7800 suspects I guess- money, motherboard space, added complexity, etc...
It has been a few years since I did this modification, so I don't remember exactly what I did, but I might revisit it again and see if I can't change it for automatic switching. I am sure there are several ways to do it.
Anyway, it is almost shocking to see how good the composite video looks in both 2600 and 7800 modes when all the signals are kept separate. It is amazingly bright, colorful and clear... Go figure.
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So... what is "it"?
Anyone have a screenshot? I am curious as well, but I don't have an emulator set up (yeah, yeah, I know it is easy- I just like real hardware and am lazy I guess...
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What a relief! I've been playing 7800 in 2600 mode for a long time, but I just got a 2600 and I couldn't figure out how to turn down the oclors.
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That's odd, I wouldn't have thought a simple switch (be it automatic or manual) would have cost much, and if the compromise was THAT significant it's certainly an odd thing to leave out.
That's at the composite video level, right, feeding into the RF modulator?
That's correct. It's in the circuit which feeds the rf modulator. Basically, I think the specifications were for somebody to be able to just plug in any cartridge, be it 2600 or 7800, and have the machine play it w/o the person having to slide a switch putting the video circuit in the correct mode. As you said, it could have been done automatically (digitally, MARIA takes over when a 7800 cartridge is plugged in, but the analog signals stay blended), but I guess it was cheaper to just mix all the signals, and work with the values and levels until the compromise was acceptable (although as pointed out, it is noticeable and I don't consider it acceptable).
Remember, the 7800 is basically a complete, independent 2600 as well as the 7800 Maria system on one motherboard. MARIA has separate Chroma, luma and Sync signals, and so does TIA. They are all blended, and basically what I did was separate them, remove several components (rf modulator, audio choke- since you don't need to blend audio with video anymore, etc), and restructure the circuit so that the signals are stronger. It really isn't that hard- if you look at the schematics in the AtariAge archives you will see how it is laid out (bottom right hand corner of schematic).
But now I have to move a switch every time I take out a 7800 cartridge and put in a 2600 cartridge- Not really a big deal if you ask me.
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The video circuit on the 7800 mixes the 2600 signal with the 7800 signal. The result is a compromise in signal strength and color in both modes. If the 2600 signal is adjusted (by changing some component values), there will be unacceptable wavy lines when playing 7800 games. It is unfortunately just the way it is unless you modify the video circuit. I was not happy with this compromise so I changed the circuit. See below for one of my prior posts...
"I see no reason to not believe that Best developed this modification from something that was done years ago. There are several different ways to build a simple video amplification circuit for the 7800; I developed mine prior to reading about the "easier video mod". One of my goals was to have crystal clear video in both 2600 and 7800 modes so the solution I came up with was to get rid of the entire rf circuit, separate the chroma signals (stock they are blended and the result is a compromise in color and image quality) and use the old channel select switch to choose between 2600 and 7800 modes. I was able to tailor the modification to have bright, non washed out colors in both 2600 and 7800 modes with individual brightness pots for each (the stock luma ladder values have been optimized for the one stage amplification circuit).
Anyway, the point is there are many ways to get composite video out of the 7800, and I think it is very possible that some engineer modified the console Best found.
"I didn't draw out a schematic (
) , or I would post it. Good luck.
Chris
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PM sent for 5 games!
Sounds great, I hope I am not too late...
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You can ship mine the way it is- I have no problem modifying it myself...
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ports
in Atari 5200
As for similarities there were none.
Umm....yeah.
Off the top of my head- the 7800 and 5200 both use the same processor- 6502 (the 2600 used a scaled back version 6507).
Depends on your definition of "similar" I guess. Many differences, yes, but they both had similar graphical resolution, just very different ways of producing it. there are many other similarities as well...
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ports
in Atari 5200
See this is what I mean. This description of atari flashback for example.
http://en.wikipedia.org/wiki/Atari_Flashback
List of games 2600 + 7800. But no 5200. Sounds kinda odd no 520 games included.
Just a suggestion, read up about the differences and similarities and "family ties" between the systems (2600/7800 and 5200) and you will have answered your own question (TIA/Maria vs GTIA).
If I remember right, the Flashback 2 is actual circuitry (although much higher integration), not emulation- that is why you can modify it to plug in real cartridges...
BTW welcome to AtariAge.
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I think best electronics have them. Maybe not listed on his website so send an email to Brad. Funny I was just thinking about this tonight before logging on
A word of caution, however:
Although I know Best is a known good resource for Atari stuff, I ordered one of their 7800 replacement bezels about 6-months ago, and specifically asked them to make sure they took the necessary precautions to avoid it getting bent. I explained that I was replacing a dented original, and suggested they ship it in a box. I think I paid about $15 + shipping
It came in an envelope, taped to a piece of cardboard, and naturally, it was bent.
I didn't attempt to contact them, and just let it go (my fault...
). Also, I assume the only ones they have are the later NTSC ones, as the rainbow was the newer style and not the earlier 1984 version (there is a difference- look very carefully at the color sequence of the rainbow).
Just FYI... CAVEAT EMPTOR
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All single Pac-Man cart orders are shipped.
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I had a 2600 and also an Intellivision. I went straight from the 2600 to a 400, so when the 5200 came out I was pretty excited until I saw the graphics and realized it was basically the same system I had been playing on for years (the 400). I was kind of disappointed in Atari, as I am sure a lot of people familiar with the 400/800 computers were as well. It was repackaged 1979 technology (with several small changes)that we had been enjoying for a long time already...
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Has anyone else noticed that Atari Corp. seems to have recycled some of the 7800 music on some of the later games? Aren't some of the sounds/music in Fatal run the same as Midnight Mutants? Or am I thinking of Planet Smashers...
I'll have to check again tonight.
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Poor sound like what the 7800 puts out doesn't annoy me. Sure 7800 Donkey Kong is a little off from the arcade, but I'll take Mario's squeaky shoes over a modern "Gangsta'" GTA soundtrack any day. I also find that even on the 7800 these soundtracks are more suitable to the game than game music today. Case in point: Kameo. This 360 game is pretty good, but the story, character models, and game world do not at all match up with its "Lord of the Rings" soundtrack. It is a fairy princess turning into a yeti to punch a cartoon goblin. Why is there an orchestra? Give me Midnight Mutants and it's silly pleepy-plop horror music please.
The sins of bad music are much worse today when it is not technology but poor judgement that causes the problems.
I agree with this. Some 7800 games have pretty good sounds considering the limitations- Midnight Mutants is a good example (and w/o Pokey to boot). There has to be a happy medium, some of the modern games have music that is way overdone and just isn't necessary or doesn't match the game.
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This sounds great!
It sounds like 2011 will continue the 7800 momentum from last year. I am very excited to see some of these new games- kudos to you!!!
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The NES has quite a few homebrew projects going for it at the moment :-
How hard can it be to program an NES game? Claim you are making a new game, then make a cart that cycles colours as if it is not connecting properly, and no one will ever know the difference.
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Well, to get back on track, this topic is "7800 vs. NES" so flicker is never an issue, at least not for the 7800...
I disagree. If you use up your MARIA bandwidth you'll see flickering. By that I mean sprites will no longer be drawn. If you get to that point in development you have to redesign the game.
Understood. Of all people you would know... I kind of meant this as a tongue-in-cheek friendly poke in the side to the NES fans anyway.
I just don't like seeing the underdog take so many punches without throwing one out as well. As this discussion is getting more "splitting hairs" technical I will try to keep my comments back to opinions and observations and leave the in-depth technical stuff to the experts...
That said, the 7800 is still better.
This thread is sort of similar to Honda fans commenting on a Harley Davidson (or Ducati, or pick your brand...) website and piling on the evidence of how the Honda is technically "superior" to the Harley. It may be true, but in the end it isn't a Harley so it really doesn't matter.
BTW- I have owned several Hondas (still do) and I am also a big Harley fan- they are both good machines.
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i have an atari 400 with a broken keyboard, would it be possible to hack an atari 800 keyboard to work? i know it will not physically fit without modifications but would it work electrically?
I did this modification way back in 1983- I used an atari 1200 keyboard (bought @ flea market) and velcroed it where the old membrane keyboard was. Electrically, yes, the number of pins is the same on several of the Atari 8-bit keyboards, although the actual connector may be different. It seems like I had to change the end on the 1200 keyboard to plug it into the edge connector for the old membrane one.
It wasn't too hard...
Replacement 800 keyboards pop up all the time for around $20 I believe. Seems like a good way to go.
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BTW- HAPPY NEW YEAR EVERYONE!!!!!!!!!!!
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I don't understand the nitpicking from Atari fanboys regarding NES graphical capabilities. Atari 2600 and SMS fans complaining about too much flicker??
Well, to get back on track, this topic is "7800 vs. NES" so flicker is never an issue, at least not for the 7800...
Oh my gosh, look at these hideous NES graphics. I don't know how anyone can stomach it. Let's play some XBOX 360 instead.
Once again, a great game that benefits from expanded ram and extra processors on the cartridge. Quite impressive, really it is, but we have nothing to compare it to in the 7800 library. Throw those same chips on a 7800 cartridge- and the Atari would have no problem impressing lots of people as well.
Who knows, maybe we'll see some good stuff on the horizon with the 7800XM.
Atari Fanboy? Never really thought about it, but I guess I am guilty...
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....and the NES has some pretty bitchin' music in W&W, Ikari 2, MM2 that I don't think anybody would compare to a hello kitty music box.
Yeah, maybe it is time I gave the NES a third or fourth chance. It is just a lot of "first impression" I have to overlook. I am sure there are some good games I am missing out on, but I just have a hard time getting past all the "most popular" ones that have been mentioned that I dislike so much. Like I said, when I think "Nintendo" I immediately think of SMB, funky Japanese graphics, kid themes, funky sprites with weird halos around them that look like they were pasted onto a tiled background, etc, etc.
Right or wrong...Halos???
Wow, you have more patience than I have @ the keyboard.
Anyway, good discussion- but I guess it is just a matter of taste. Growing up in a heavily Atari influenced era (not just VCS, but 400/800, 5200, etc.), I noticed a distinct difference in the look and feel of the games post Nintendo, and as I said, I don't care for it. The younger generation would not necessarily feel this way as they grew up with the Nintendo graphics. I feel the same way about today's cartoons compared to the Merry Melodies and Looney Toons of the past. Back to games, it was/is an artistic change of culture compared to the way the games began and the way they were going in America and Europe. I prefer any Ultima over Zelda, I just wish the old ones were bigger with better graphics
.As far as halos, that is probably not the best description... but this is kind of what I mean as far as the characters looking like they are moving in a plane right above a tiled background and are not cohesive with it- maybe it is also just the poor color choice.
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Opinion of the 7800 vs 8bit
in Atari 8-Bit Computers
Posted
Groovybee- I am glad you are around to champion for the 7800. It has been the "redheaded stepchild" Atari, and generally missunderstood for far too long.
The A8's have always been my favorite 8-bit machines to play games on, but the 7800 has some great possibliities that were never exploited until now- and there will be more suprises in the future. So anyway, I just wanted to publicly say that I am very happy you are doing so much for the 7800, so that we will have more examples to show off it's capablilities... I for one, am very excited about the 7800 scene.