Looking for 7800 programmer to assist porting a game

[Trebor]

What would be a rough estimate on total number of cartridges I can expect to sell per game?

 

A lot depends on how the consumer views the game you develop and have published.

 

Worst case scenario is likely a handful with absolute best case scenario being several hundred over time:

 

-Anything on cart = Handful or two.

-Subpar game = Dozen or two.

-Good game = Dozens to a hundred or so.

-Exceptional and 'popular' game = Couple to several hundred.

 

Having been a part of and continue to partake in many homebrew development endeavors, it can be a near guarantee that the amount of time and effort placed into developing for the 7800 does not even come close to minimum wage returns. Thus far, the best 7800 homebrews are those which were motivated and driven by a labor of love.

[Synthpopalooza]

I thought about how Super IRG, going between 2 fonts each TV frame, will work with the 7800. It should work for the 160 pixel wide modes. Those 320 pixel wide modes are weird on how they are set up, can those be used for a Super IRG like trick also?

 

I selected a few games that may be ported to the 7800. Including Amok Bots, Delta Space Arena, and Laser Blast X. Favoring games that not really been done much 7800. I am skipping over Megaoids and Helicommander because the 7800 already has decent ports of Asteroids and Choplifter.

 

Question for people that already had produced games on these cartridges, either selling through Albert, on on their own. What would be a rough estimate on total number of cartridges I can expect to sell per game? From working with the 8-bit games selling through Atarisales, I can say the average is around 30 with the smaller games. Tempest and Venture games sold over 50. Not sure how many people have actual 7800 consoles in this world. The ideal with doing sever other games that fit onto a 16K cartridges was to offer people a choice. People may like space shooter games, military war games, puzzles, or adventure.

You can do Super IRG on 320B but it requires setting Kangaroo mode on to kill transparency and unlock all the colors. You get a 9 color + bg 320 pixel mode. I used this for my Sky Scraper title.

 

The only other one where it might be useful is 320D. This is one of the weird ones Where you get all 8 palettes, but even columns get colors BG and 1, odd columns get 2 and 3. Só to do the trick, you set color 2 and BG to the same value, and do a color register swap between 1 and 3 when you do the character swap. In theory this should get you 4 colors per character at 320 pixels, across 8 palettes. This is also useful because 320D uses less overhead than 320B. The interlacing happens in vertical 320 pixel strips instead of checkerboards.

Edited October 21, 2017 by Synthpopalooza

[peteym5]

All the existing games I plan to port over are originally in Antic 4, the 8-bit 4 color character mode. Several of them used semi Super-IRG, where only a few things on screen had extra colors. Complaints I get mostly comes from people using PAL systems that have a lower frame rate. I have to look up on how top 2 row character display at the top or bottom at 40 column 8x8 characters, and the rest of the screen be 160 mode for the game play field.

 

The game we are looking to start with is Delta Space Arena, which is a space shooter, lots of action, great graphics on the 8-bit version. It sold many copies so far. Currently being tested to run on the 5200. I can ever improve on a few things porting it over to the 7800 like extra controller options to work with trackball or driving controller.

[Synthpopalooza]

That's actually not too dofferent. The 7800 hardware has a register called CTRL. Setting certain bits of it will select between hi-res (the 320 modes) and the 160 modes. It is also possible to change it in an interrupt where the top lines of the screen are in 320 while the bottom is in 160. You want to do this near the top as this uses less cycles and eats up less DMA.

 

I strongly suggest looking up 7800 Basic which has a built In topscreen routine that you can tweak to change graphics modes and color registers on the fly.

 

Antic 4 correlates with 160A mode. It displays 3 colors plus BG per character but you can choose from 8 palettes. You don't want to do a lot of palette changes per character line because that eats into your cycles and DMA.

 

This is your recommended setup, and you can then do your sprites in either 160A or 160B ... 160B is workable with sprites atop 160A charmap, it gives 12 colors per sprite, although the memory and DMA cost will be greater.

Edited October 21, 2017 by Synthpopalooza

[Synthpopalooza]

One other caution:

 

If you use 320 for your play field, you can use 320B 4 color mode for sprites, but some colors will not display when paired with your background color. This is alleviated by changing a bit in CTRL to turn on Kangaroo mode, but then this will also make your sprites non transparent. Black squares will show up instead of a transparent sprite background.

[peteym5]

I may use 320 text mode for the score board display at the top of the screen, but 160 wide modes be the primary display for the game play fields. I have to look up on these modes are set up on different portions of the screen.

 

Right now I am working out a way to port the 8-bit font character graphics to a bitmap image that can be translated with the 7800 graphics converter. Easiest thing to do is have Altirra display all 128 characters in Antic 4, save screenshot for the other program. I know the 7800 Maria arranges the bits differently than how Antic/GTIA just arranges them with the bit pattern. I could also write a program that just re-arranges the bits for the 7800, if someone hasn't done it already.

[CPUWIZ]

I am curious about the cart production, are you using new circuit boards, or is this all recycled stuff from old games? Thanks.

[video61atarisales]

I am curious about the cart production, are you using new circuit boards, or is this all recycled stuff from old games? Thanks.

they can be both. before my accident you sold me six of them to experiment with, i never got to, now i do not know where they are. i have lots of ones i can recycle, but i would rather use new, less work. so do you still have any for sale?

 

thanks,

 

lance

www.atarisales.com

[CPUWIZ]

Oh, hey Lance, hope you are doing better. I am sure I have some, IIRC you were only going to use the normal 48K config and not fancy bankswitched stuff, right? I'll hit you up via PM, when I get my next batch from China, I should have 50-100 of those.

[Synthpopalooza]

I may use 320 text mode for the score board display at the top of the screen, but 160 wide modes be the primary display for the game play fields. I have to look up on these modes are set up on different portions of the screen.

 

Right now I am working out a way to port the 8-bit font character graphics to a bitmap image that can be translated with the 7800 graphics converter. Easiest thing to do is have Altirra display all 128 characters in Antic 4, save screenshot for the other program. I know the 7800 Maria arranges the bits differently than how Antic/GTIA just arranges them with the bit pattern. I could also write a program that just re-arranges the bits for the 7800, if someone hasn't done it already.

I used precisely this method (a screen shot from my ICE editor in Super IRG running in Altirra) to do the sky scraper title screen. You can do the screenshot, and arrange it as a sequential png, use Gimp to posterize to 4 colors and export a PNG. 7800basic will import it for you.

[peteym5]

This is what I extracted from Delta Space Arena and converted so far. I know that the colors do not match what is in the game, but we change the palette colors inside the program all the time. The Antic 3 Font image is also included. Didn't I read somewhere that the 7800 can only display from a font that is only 256 bytes long, within the same memory page. There should be a work around this, but we only use this for the scoreboard at the top of the screen.

 

The one game I am not considering right now is Tempest because it would be very difficult to draw the webs. Needs an 8k screen in RAM to do the line drawing. I thought about a character mode solution to this, comprised of characters of all the possible line drawing angles.

 

I should ask everyone what games from my collection would you like to see ported over to the 7800.

 

[Synthpopalooza]

Actually not accurate. The font has a limit of 256 characters and they have to be from the same block. You can actually use several fonts but all up it has to fit in 256 characters. The size of the font depends on two settings: Graphics Mode, and single wide vs double wide.

 

160B möde allows 12 colors + BG but the colors are organised in nibbles like GTIA modes on the 8 bit. So each character is 2x8 pixels, or 4x8 if you set doublewide. It uses more ROM space than if you use 160A which is 4x8 pixels single wide or 8x8 doublewide.

 

The other limitation is you can only plot 32 characters of width at a time. You can break up the screen into 20 column halves however and plot them sequentially.

Edited October 22, 2017 by Synthpopalooza

[Synthpopalooza]

The other thing is if you do Super IRG tricks, you have to have each font half on separate graphics blocks in the same position and you can't put any sprite graphics there. You swap the character set pointer every drawscreen to do the effect.

[video61atarisales]

Oh, hey Lance, hope you are doing better. I am sure I have some, IIRC you were only going to use the normal 48K config and not fancy bankswitched stuff, right? I'll hit you up via PM, when I get my next batch from China, I should have 50-100 of those.

thanks, very slow, perhaps another 1-2 years, but its better than it was four years ago for sure. yes, so far we are sticking to 48k or less. i will surely buy them. perhaps you have one available now for testing?

also, if we want larger configurations in the future, will you have a board for that to?

 

thanks,

 

lance

www.atarisales.com

[Jinks]

This is what I extracted from Delta Space Arena and converted so far. I know that the colors do not match what is in the game, but we change the palette colors inside the program all the time. The Antic 3 Font image is also included. Didn't I read somewhere that the 7800 can only display from a font that is only 256 bytes long, within the same memory page. There should be a work around this, but we only use this for the scoreboard at the top of the screen.

 

The one game I am not considering right now is Tempest because it would be very difficult to draw the webs. Needs an 8k screen in RAM to do the line drawing. I thought about a character mode solution to this, comprised of characters of all the possible line drawing angles.

 

I should ask everyone what games from my collection would you like to see ported over to the 7800.

 

Venture please.

[peteym5]

We will eventually be porting most of the games in my inventory over to the 7800 if the first one we works out well. Venture has been added to the list.

 

With the 7800 cartridges, how is the extra RAM normally mapped? Is it always available? I need to see which board types have sockets for both RAM chips + EPROM, and who has them.

[Mord]

Most of the time I believe extra ram is usually mapped in the $4000-$7FFF range for 16k. Some formats will have 32k available as 2 16k banks in that range.

[Trebor]

For some games, such as Impossible Mission and Jinks that utilize just 8K RAM, it is mapped from $6000-$7FFF, according to the bankswitching guide posted by Eckhard Stolberg.

[peteym5]

Well Venture is now one of the listed Atari 7800 games to be ported over. I can make the sprites multi-colored and sprites not be limited to the player/missile sizes. I made up a small image of what the sprites may look like on the 7800. I can make it more arcade like.

 

We will be producing these games for the stock 7800 and will not be taking advantage of any special upgrades or modules, like that XM module.

Edited October 24, 2017 by peteym5

[tep392]

Now I know the 7800/Maria can put 8 multicolored sprites on screen at once, drop down to 7 if you want to have background/character mode.

You should avoid thinking about the 7800 sprite capability in terms like "how many objects per line". It can be much more than 8 or even less than 8. You should think in terms of how much time does Maria have to draw the objects. Is there character mapped background to draw and how wide is it? If the background is sparse, it might be more efficient to build it with objects. Each object requires some overhead clock cycles plus the time to draw each pixel. How many colors and what width are the objects? Some might be 4 pixels wide while others are 32. So until you layout your screen and define the color depth and width of your objects, you don't really know how many objects per line you can draw. All you know is how many color clocks Maria has to work with.

Also, give 7800basic a good look. It is very efficient and handles the display list complexity for you. You can put assembly code in line with your basic code making it very easy to combine the two. Heck, you could use basic only for the graphics and just plunk all your game code in as strait assembly.

edit:

I made the score line in Donkey Kong PK using objects instead of character graphics. I needed to squeeze in more characters than what was possible in 8 pixel wide chunks. The objects are still defined as 8 pixels wide but they are spaced closer. The black space of the adjacent objects actually overlap. "1UP", "2UP", "HI" and each number are an object, so 21 total on that line. No programming tricks necessary.

[Synthpopalooza]

Well Venture is now one of the listed Atari 7800 games to be ported over. I can make the sprites multi-colored and sprites not be limited to the player/missile sizes. I made up a small image of what the sprites may look like on the 7800. I can make it more arcade like.

 

We will be producing these games for the stock 7800 and will not be taking advantage of any special upgrades or modules, like that XM module.

This includes using stock TIA sounds and no POKEY?

[peteym5]

Right now, we are focusing on games that can be just an EPROM with no RAM or Pokey chips because those are not as expensive to make and sell. I was referring to external modules like that XM module, or any special internal upgrades people may had done to their 7800 like adding stereo pokey board inside the system. The music and sound for Venture may be simple enough to do with just TIA, but right now I am figuring out the graphics part of these games. This XM module sounds great, but looks like people are loosing faith in that thing.

 

Most of the games only have 8 to 12 sprites moving around at once. Delta Space Arena may need as many as 20. Venture only had 8, so I figure it can handle most of the games I plan to put together. The Miniature Golf can be set up to only use 7 objects.

[Jinks]

Yes Venture! Would be great to have the best 8 bit console version of this game!

[Synthpopalooza]

Well Venture is now one of the listed Atari 7800 games to be ported over. I can make the sprites multi-colored and sprites not be limited to the player/missile sizes. I made up a small image of what the sprites may look like on the 7800. I can make it more arcade like.

 

We will be producing these games for the stock 7800 and will not be taking advantage of any special upgrades or modules, like that XM module.

You could do this game in 320 mode. 320B for your player and 320A (mono colored sprites) for the enemies and the character map. I think it would look great.

[Trebor]

Sticking as close to the Arcade original as possible, Venture seems to work well and is a great fit for the 320 mode(s).

 

The Arcade features one color enemies and even Winky is monochromatic. Winky's bow is the same color as he is in the game. The yellow is only attached to the shooting arrow.

 

Absolutely as always, developer's prerogative, though if sticking with enhancing the original graphics looks with multi-colored sprites, then it may look better balanced if both player and enemies are handled with multi-colors utilizing the 160 modes. Otherwise, keeping it as Arcade 'exacting' as possible, those 320 modes can really make the game shine to graphic perfection.