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Homebrewing and the 7800


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#1 MegaManFan OFFLINE  

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Posted Sat Jan 18, 2003 12:53 PM

I've been wondering about something over the last few days. As we all know, homebrewed games are plentiful on the 2600 (despite the technincal limitations of programming for it) and there are more than a fair share for 5200 as well (some quite complex). The 7800 seems to be a mystery though. A few prototypes have been unearthed, at least one (Klax) had a few print runs that were successful, but nobody seems to be homebrewing games specifically to take advantage of the 7800. Is it because..

(1.) The installed console base is lower than the 2600 or 5200?
(2.) Minimal third party development means the specs aren't well known?
(3.) Getting it to run in 7800 and not 2600 mode is too difficult?
(4.) Nobody gives a sh#%?

I'm curious to what people think and/or if anybody out there smells a homebrew in the wind for 7800 that we just haven't heard about yet.

#2 ubersaurus OFFLINE  

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Posted Sat Jan 18, 2003 1:03 PM

Well the 7800 mode problem was solved a little while back, I know that much... I guess it's just because it wasn't an overly popular system. Same with why there are few master system homebrews, I guess.

#3 MegaManFan OFFLINE  

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Posted Sat Jan 18, 2003 2:05 PM

ubersaurus said:

Well the 7800 mode problem was solved  a little while back, I know that much... I guess it's just because it wasn't an overly popular system. Same with why there are few master system homebrews, I guess.

I still haven't seen an SMS homebrew put on a cart (or that would be worthy to, for that matter). I have a feeling a 7800 would be better supported even if the installed console base was smaller, because of the very concentrated amount of Atari fans that could be reached through just a few sites like AA.

#4 Mitch OFFLINE  

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Posted Sat Jan 18, 2003 2:20 PM

I know of a few 7800 homebrews that were started but nothing has been finished yet. I think part of the problem is a lack of documentation and experienced 7800 programmers that can offer tips. The fact that, until recently, the encrytption wasn't available also was a problem. Hopefully this year will see the first 7800 homebrews. :)

Mitch
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#5 Heaven/TQA OFFLINE  

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Posted Sat Jan 18, 2003 4:52 PM

compared to 2600 7800 is a dream... but the architecture is different to 800 line... that's why it is more hard to code... but not impossible... unfortunatly i have lost some of the sources through a harddisc crash.

lack of installed base and lack of interest is leading to lack of code... don't forget that this goes hand in hand in missing tools for converting data, etc...

hve

http://www.s-direktn...nadj/a7800.html

#6 Nostalgic OFFLINE  

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Posted Mon Jan 20, 2003 4:31 PM

I looked into it for a little while. I did get quickly discouraged by the number of obstacles in the way. The first was the encryption - while the code has been cracked of a sort, the only ways I could gather were to either modify a 7800 (no way!) or graft some code onto the binary each time it is generated. Ick.

The second was displaying images. While you don't have the same difficulties as with 2600 programming, the 7800 has its own weirdness. Images are often stored such that each row is one page apart rather than one byte. You have to construct display list headers and display list lists (really!) to tell the 7800 where the images are and how to draw them. (By the way, "display list" is completely different than the type used in the 5200 and the 8-bit computers.)

The third, of course, is the lack of sample code. For the 2600, you have plenty of source code for completed homebrews and some skeleton code to use as a starting point, like Nick Bensema's "How to Draw a Playfield" and "Guide to Cycle Counting." For the 5200, you could probably adapt a lot of what's been published by Antic, Analog, and Compute! about the 800 series. For the 7800 - not much at all. You'd still have to compile it so that it can be run, which requires dealing with encryption, bringing you back to the first obstacle.

#7 Heaven/TQA OFFLINE  

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Posted Mon Jan 20, 2003 5:09 PM

and that's exactly the challenge... :D

and with the display lists you can do nice things... remember f.e. up to 256 pixel wide sprites! or hardware sprites with each own 3 colors.... so real "arcade" feeling... unfortunatly the vertical movement of sprites is harder than on other systems but not impossible... see robotron2084 which source is complete avaible on dan boris' website if i remember it right....

hve

#8 Mitch OFFLINE  

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Posted Mon Jan 20, 2003 7:35 PM

Nostalgic said:

I looked into it for a little while.  I did get quickly discouraged by the number of obstacles in the way.  The first was the encryption - while the code has been cracked of a sort, the only ways I could gather were to either modify a 7800 (no way!) or graft some code onto the binary each time it is generated.  Ick.

The second was displaying images.  While you don't have the same difficulties as with 2600 programming, the 7800 has its own weirdness.  Images are often stored such that each row is one page apart rather than one byte.  You have to construct display list headers and display list lists (really!) to tell the 7800 where the images are and how to draw them.  (By the way, "display list" is completely different than the type used in the 5200 and the 8-bit computers.)

The third, of course, is the lack of sample code.  For the 2600, you have plenty of source code for completed homebrews and some skeleton code to use as a starting point, like Nick Bensema's "How to Draw a Playfield" and "Guide to Cycle Counting."  For the 5200, you could probably adapt a lot of what's been published by Antic, Analog, and Compute! about the 800 series.  For the 7800 - not much at all.  You'd still have to compile it so that it can be run, which requires dealing with encryption, bringing you back to the first obstacle.

Umm, the encryption program has been found, and a DOS version has been made that is quite easy to run. Check out Dan's 7800 web site for it as well as some sample code.

You are right about there not be much info out there. However, if you check Dan's page and the 7800 FAQ you can find links to several sources of info.

Also, there is no need to modify your 7800, you can develop in the MESS emulator instead. You don't even need to encrypt you game if you don't want to if you are using Eckhard's BIOS instead of the standard one.

Mitch
http://atari7800.atari.org

#9 Harry_Dodgson OFFLINE  

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Posted Tue Jan 21, 2003 5:56 AM

Mitch said:

I know of a few 7800 homebrews that were started but nothing has been finished yet. I think part of the problem is a lack of documentation and experienced 7800 programmers that can offer tips. The fact that, until recently, the encrytption wasn't available also was a problem. Hopefully this year will see the first 7800 homebrews. :)  

Mitchhttp://atari7800.atari.org

Should I be insulted (multiple times) by this posting?

#10 DanBoris OFFLINE  

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Posted Tue Jan 21, 2003 11:42 AM

Nostalgic said:

The second was displaying images.  While you don't have the same difficulties as with 2600 programming, the 7800 has its own weirdness.  Images are often stored such that each row is one page apart rather than one byte.  You have to construct display list headers and display list lists (really!) to tell the 7800 where the images are and how to draw them.  (By the way, "display list" is completely different than the type used in the 5200 and the 8-bit computers.)
.

The trick to conquering the 7800's graphics system is to think of it as a 2 step process. Instead of going directly from game logic to the data structures, you can have an another layer of code in between, a display engine. The display engine could, for example, take a table that contains the sprite postions and what "character" to use for each sprite, and convert this into the data structures that the Maria graphics chip uses. Now you game logic writes to the table, and then you call the graphics engine once per frame to setup the data structures. The cool thing about this is that it allows you to write display engines that mimic almost any type of graphics hardware.


Dan

#11 Mitch OFFLINE  

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Posted Tue Jan 21, 2003 3:02 PM

Harry_Dodgson said:

Should I be insulted (multiple times) by this posting?

No Harry, it was not intended as an insult towards you. I guess I consider you as one of the original 7800 programmers and not a homebrewer. :)

I'm sure if you'd care to write a new 7800 game everyone would be happy to buy it. :thumbsup:

Mitch
http://atari7800.atari.org

#12 Nostalgic OFFLINE  

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Posted Tue Jan 21, 2003 5:02 PM

Mitch said:

Umm, the encryption program has been found, and a DOS version has been made that is quite easy to run. Check out Dan's 7800 web site for it as well as some sample code.

I had wandered through there. I may not have understood how to use the validation key generator. It sounded like you'd have to run it every time you recompiled your code, which isn't appealing. It's quite possible that I misinterpreted things. If so, I'll feel sheepish. :)

Quote

Also, there is no need to modify your 7800, you can develop in the MESS emulator instead. You don't even need to encrypt you game if you don't want to if you are using Eckhard's BIOS instead of the standard one.

I wasn't aware of this. However, I found it invaluable to work on an unmodified 2600 when I was creating Euchre, so I can't see not wanting to run a 7800 game on the real thing during development.

#13 Mitch OFFLINE  

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Posted Tue Jan 21, 2003 7:44 PM

Nostalgic said:

Mitch said:

Umm, the encryption program has been found, and a DOS version has been made that is quite easy to run. Check out Dan's 7800 web site for it as well as some sample code.

I had wandered through there. I may not have understood how to use the validation key generator. It sounded like you'd have to run it every time you recompiled your code, which isn't appealing. It's quite possible that I misinterpreted things. If so, I'll feel sheepish. :)

Quote

Also, there is no need to modify your 7800, you can develop in the MESS emulator instead. You don't even need to encrypt you game if you don't want to if you are using Eckhard's BIOS instead of the standard one.

I wasn't aware of this. However, I found it invaluable to work on an unmodified 2600 when I was creating Euchre, so I can't see not wanting to run a 7800 game on the real thing during development.

How were you planing on testing the game on a real 7800? Do you have an EPROM burner and EPROM cart?
There are a couple 7800 RAM carts currently in development and at least one of them doesn't require the encryption in the game.
One last point, if you are burning EPROMs, adding the encrption is a very minor extra step. It's simple and only takes a second or two for it to run. 8)

Mitch
http://atari7800.atari.org

#14 Allan OFFLINE  

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Posted Tue Jan 21, 2003 7:54 PM

What the 7800 needs is for someone to write a tutorial like there is for the 2600 and 5200/8-bit. I think that would help start more people writing games for it.

Allan

#15 Clint Thompson OFFLINE  

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Posted Wed Jan 22, 2003 2:31 AM

I have always wondered the same thing....
...I've always been a bigger fan of the 7800 just because it was
supperior to the 2600...

I could imagine you could do some pretty neat things with the 7800 given the time and knowledge!

Com''on someone ;-)

Clint Thompson
:P

#16 Harry_Dodgson OFFLINE  

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Posted Wed Jan 22, 2003 6:18 AM

Mitch said:

Harry_Dodgson said:

Should I be insulted (multiple times) by this posting?

No Harry, it was not intended as an insult towards you. I guess I consider you as one of the original 7800 programmers and not a homebrewer. :)

I'm sure if you'd care to write a new 7800 game everyone would be happy to buy it. :thumbsup:

Mitchhttp://atari7800.atari.org

I've had a few people try to get me to do something on the 7800...
It's just so much easier to do games for the Lynx. If you have seen
the code for BumperTanks, you'd know how much work goes into a
fairly simple demo for the 7800. Plus, the Atari tools for the 7800
look very bad when compared to the Epyx tools for the Lynx. It's
just one of those "path of least resistance" decisions.

Harry

#17 Heaven/TQA OFFLINE  

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Posted Thu Jan 23, 2003 2:10 AM

8) 7800 is really easy...

from programming level and knowledge: (easiest 1st)

- 400/800
- 5200
- 7800
- LYNX
- GBA
- PSX
- C64
- ...
- 2600

just my personal ranking... i have done code on all of the machines... PSX seems really similar to GBA & 7800 with the display list tile based system... (primitives).

2600 is for me a mystique box... :) it would take me ages just to write a kernel routine... no thanks... ;)

http://www.s-direktn...nadj/a7800.html

get the tools and you can kick off A7800 coding...

hve

#18 Harry_Dodgson OFFLINE  

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Posted Thu Jan 23, 2003 5:43 AM

Heaven/TQA said:

8) 7800 is really easy...  

from programming level and knowledge: (easiest 1st)

- 400/800
- 5200
- 7800
- LYNX
- GBA
- PSX
- C64
- ...
- 2600

just my personal ranking... i have done code on all of the machines... PSX seems really similar to GBA & 7800 with the display list tile based system... (primitives).

2600 is for me a mystique box... :) it would take me ages just to write a kernel routine... no thanks... ;)

http://www.s-direktn...nadj/a7800.html

get the tools and you can kick off A7800 coding...  

hve

I see according to your list, that you think the 7800 is easier than the
Lynx. What tools are you using for each one? I like using any paint
program I want to do Lynx sprites (even boring Paint included with
all windoze systems), covert it to 16 or 32 color IFF format,
and handycraft does the palette, compressed sprite data, and SCBs
for me. I create the template and file directory for my code and
handyrom builds the image for me. Then I pass all this
good stuff into a Howard board and I get real time testing and
debugging with (symbolic) instruction and bus backtracing ability. I
couldn't ask for a more friendly development environment.

Harry

#19 Heaven/TQA OFFLINE  

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Posted Thu Jan 23, 2003 7:14 AM

hmmm... :) are these custom PC tools? and the official lynx ones??? i have a Lynx 2 but never touched it with coding... just small routines with the Handyemulator but it was no problem to have a big TAQUART logo sprite zooming... just converted with tools found on the net...

hve

#20 Jetboot Jack OFFLINE  

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Posted Fri Jan 24, 2003 2:41 PM

Having investigated 7800 homebrew as an alternative to my current 400/800 efforts I've decided to stick with the 8bit. The toolchain is just not as good, I can get many more useful PC and 8bit utils than stuff for the 7800 :(

But I would be very interested to learn of any great LYNX tools out there to allow me to develop for that - I wouldn't want to target real hardware at first I'm more than happy to build cart images and use Handy or the like to test with - but what tools are there - can anyone enlighten me??

sTeVE

#21 CPUWIZ OFFLINE  

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Posted Fri Jan 24, 2003 2:56 PM

Jetboot Jack said:

Having investigated 7800 homebrew as an alternative to my current 400/800 efforts I've decided to stick with the 8bit. The toolchain is just not as good, I can get many more useful PC and 8bit utils than stuff for the 7800 :(

But I would be very interested to learn of any great LYNX tools out there to allow me to develop for that - I wouldn't want to target real hardware at first I'm more than happy to build cart images and use Handy or the like to test with - but what tools are there - can anyone enlighten me??

sTeVE

Check Bastian's website ...

http://www.geocities...Byte/4242/lynx/

#22 Jetboot Jack OFFLINE  

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Posted Fri Jan 24, 2003 3:36 PM

Thanks for the infos!

sTeVE

#23 Nostalgic OFFLINE  

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Posted Fri Jan 24, 2003 4:24 PM

Mitch said:

How were you planing on testing the game on a real 7800? Do you have an EPROM burner and EPROM cart?
There are a couple 7800 RAM carts currently in development and at least one of them doesn't require the encryption in the game.

Well, I was hoping that something would materialize while I was working on it. :) I have no aptitude with electronics, so I certainly wouldn't try one myself.

I wonder if the 2600 flash cart that Cupcakus is working on is compatible with a 7800...

Cupcakus: if you read this forum, please let us know!

#24 Mitch OFFLINE  

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Posted Fri Jan 24, 2003 10:29 PM

Nostalgic said:

I wonder if the 2600 flash cart that Cupcakus is working on is compatible with a 7800...

Cupcakus: if you read this forum, please let us know!

No, I'm afraid it wouldn't work with 7800 games.

Mitch
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#25 Atari Joe OFFLINE  

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Posted Tue Feb 25, 2003 2:27 AM

if you ask me the best way to make a 7800 home brew is you get one of the harry dogson monitor cartridge and then you plug that into the cerial port on the xe or the st or even on a pc and then you can make your own 7800 game. i see first hand all the new games being made and boy let me tell you that with the monitor cartridge you can do anything. you can take 8-bit games and then with the source code you can make them into 7800 games and then add on maria programing and boy let me tell you it is slick as can be. -Joe




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