Tubular Gearhead

MG used leaf springs right?

I think we can stick a fork in this thread... I'm pretty sure it's usefulness is over.

Exactly what PARTICULAR GROUP are you referring to.. I'd sure like to know, since I did not specify any such group.. Why, the Liberal Human Garbage Group, of course (or LHGG as we like the call them). The influence of this noble body can be felt everywhere in modern society. That's why it's such a glorious world we live in, where everyone's just as talented and intelligent as everyone else, no-one can be rejected or excluded from anything, risk is intolerable and is being gradually eradicated, rules are really "guidelines", and everyone's allowed to mess up at least a hundred times before they start running out of second chances. Fortunately, in accordance with LHGG guidelines, we'll be obliged to hold a full and open enquiry into the banning incident, and the ejected member will be entitled to handsome compensation on grounds of discrimination. In fact, since he had two accounts, he'll be entitled to double compensation. He'll also receive counselling... meanwhile, we'll be obliged to endlessly debate the lamentable loss of playground slanging matches on the forum. Seriously... I'm glad we have at least one person here (MG) who's not afraid to say it how it is, and I sincerely hope we don't spend another 1K posts pointlessly discussing how we could have done things differently. There must be better things to talk about... I believe this humorous take on the situation hits the nail on the head, and I'll second the message contained here. Although MEtalGuy66 might have chosen to be a little less frank, I don't think he meant to offend anyone, just to point out that people have to be held accountible for their actions. Unfortunately, those most offended by these ideas tend to be the same people who want to live in a conseqence free world (and also interpret a particular political alignment where there was none intended)... But hey... where's that popcorn?

Sorry for bumping up a thread from last summer, but... I just compared my green Polaris last night, and it also weighs more than my other Tigervision carts. Can anyone confirm that they have a green Polaris that doesn't weigh more? Maybe it is just a characteristic of all the green versions? Anyone have any other thoughts on this?

I promiss guys, I will take good care of it.

You really should understand the 7800 at a technical level before commenting . Graphics crippled eh? You can do an APAC like display (169 colours) at an effective resolution of 126 x 80 (X x Y) on a stock 7800 machine. With additional RAM on cart that increases to 160x80 which is twice the x resolution than the A8 can do. The 7800 can place a 13 colour sprite on top of any 4 colour backgrounds or other sprites anywhere on screen. The 7800 can mix and match 13 colour graphics and 4 colour graphics in any way the programmer imagines given the limits of RAM or the bandwidth of MARIA. The 7800 can display 25 colours horizontally per scan line without programmer tricks. In 320A mode (1BPP) MARIA can display its graphics using 8 palettes thus allowing 9 unique colours per scan line to be achieved without programmer tricks. In 320B mode (2BPP) MARIA can display its graphics in 4 colours using 2 palettes thus allowing 7 unique colours per scan line to be achieved without programmer tricks. The 7800 doesn't have an OS. It has a BIOS which is used to identify the cart type 2600/7800 and on NTSC machines it puts up a logo and checks the cart signature. The BIOS is switched out of the memory map to allow games to boot. You've obviously missed the port of Tempest to the 7800 that I did from the BBC micro computer. Tempest usess a frame buffer which is constructed in cart RAM. 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.

+1 I second the motion. I have both, love both, play both.

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!

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.

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.

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... ).

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.

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

PM sent for 5 games! Sounds great, I hope I am not too late...

You can ship mine the way it is- I have no problem modifying it myself...

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...

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.

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

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...

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.

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.

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!!!

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.