DanBoris

Here's my most inspirational "in the wild story". There is a local flea market that I went to every weekend, and there is one stand that always had a bunch of commons, which rarely changed. They where in bins with a bunch of them upside down, so I one day I stared going though them turning over one Combat and Space Invaders after another. About 3/4 of the way through I was just about to give up and walk away, but something made me flip over a few more carts, and low-and-behold I flip over an Atari cart and it's Swordquest Waterworld! Got it for $1.00.

I think the major reason is that up until very recently there wasn't much information on how to program the 7800. The other problem was the encryption key for the carts. Until late last year there was no way to generate these keys, so there was no way to produce real carts that would run on an un-modified 7800. There are some people doing 7800 development, and I think once people start learning the system, there will be more new games developed for it. Dan

Two possible problems. First are you clearing PF1 at the start of the frame? If not then it will always display the same pattern. Also, if you want to only display on that single line you will have to clear PF1 after that line. Dan

So, assuming you don't use the stack for anything else, you can have 128 nested subroutines. This would be slightly less on a 5200 because of interrupts which also push stuff on the stack. Dan

Well, when I am in a video game mood, I listen Good Deals Games on Live365.com. Great streaming media station for people into classic video games. Plays all Buckner and Garcia songs, video game music, interviews with classic game authors, etc. Very cool station. Dan

quote: Originally posted by Cafeman: Dan, what platforms can I make games for using 68000? Could you list all that you know? Why did you learn 68000? I learned it for my job, so I could write test programs for 68000 based data communications equipment I was troublshooting/repairing. Dan

quote: Originally posted by Cafeman: I only know 6502 ASM right now, and I'm no expert. I also plan on learning 68000 ASM someday soon. I know you can make Genesis games with it, and if I'm reading this thread correctly, Jag games use 68000 ASM too. Does the GBA use an ASM language too, or if not, what is the language used for GBA development? You are going to love 68000 assembly. I made the transition from 6502 assembly to 68000 a bunch of years ago, and boy was it a dream! After doing 6502 coding, working with the 68000 is almost like programming in a higher level language. Dan

I have programmed in a number of different assembly languages, and I have to say that 68000 assembly is one of the easiest. Of course this is all relative since programming in any assembly language can be a daunting task. Also, programming a system like the Jaguar can be particularly difficult since it's hard to get help on how to do it, you can't go to the store and pickup a book on Jaguar programming so you will have to work out a lot of things on your own. Dan

quote: Originally posted by -^Cro§Bow^-: Okay Dan, ...or there is still something amiss in the 7800 driver on Mess for the Pokey support. Most likely this is the problem. It's unlikely that a bad dump would only cause music to be missing. I'll have to find some time to take a look at this problem. Dan

The POKEY is DEFINITLY supported in MESS, I know, I put it there The Pokey emulation in the MAME/MESS core is pretty accurate so the POKEY emulation in the 7800 driver should be complete. I will have to checkout Ballblazer on my real 7800 to see what you mean about the music. Also, as Eckhard indicated the audio line coming from the cart (where the pokey is) does get mixed with the audio from the TIA so you can get 6 channels of sound. I have often thought about why Atari didn't include a Pokey onboard. Space was definitly an issue, the 7800 logic board is pretty tight and the POKEY is a 40 pin IC so the would have had to increase the size of the board. I may have also been for economic reason. Since they would have had to make the board bigger it may have increased the cost more the just the price of the POKEY chip, and at that time, they selling price of a console was a very important issue. Putting the Pokey on the cart on the other hand didn't really hurt Atari much since most carts had either extra ROM or RAM on them anyway (POKEY carts had neither) so the cost to make any supercart would have been about equal. Dan [ 02-18-2002: Message edited by: Dan Boris ]

I belive the PAL and NTSC TIAs are different. Best Electronics lists the CO104444D as a TIA, and CO11903 as a PAL TIA. Dan

You can get them from Best Electronics: http://www.best-electronics-ca.com/ Part number CO11903 (PAL "TIA" 2600) $8.00 Dan

As you suspected the problem with this is how much time Maria has to get the data into the scanline. For each scanline you have 456 Maria cycles to generate the scanline. Each byte you transfer to the scanline requires 3 cycles. If you used the 160x2 mode which would give you 160 pixels across in 4 colors, it would require 40 bytes to cover the whole scanline. So 40 * 3 = 120 + 8 (for the header) = 128 cycles per line. So you could only 3 different graphic lines on one scanline. Dan

Here is an arial photograph from Mapquest of the area where the Atari headquarters used to be. Appears that most of the building are still there, and can be matched up with the map mentioned above. http://www.mapquest.com/maps/map.adp?mapdata=xU4YXd

You can run some 2K and 4K rom images on an un-modified Supercharger. There is a program by Bob Colbert called Makewav that converts the .bin files to .wav files that Supercharger can load. The reason the modification is needed for some games is that the Supercharges uses a series of memory locations to control it's bankswitching and RAM etc. So if a game tries to use these addresses it will crash. You can get more info here: http://members.home.com/rcolbert1/super.htm Dan

This gets a lot more complicated then the 2K and 4K carts. The 2600 can only directly address 4K of cartridge ROM, so to access the bigger ROMS you have to do bankswitching. To make a copy of a 8K or larger cart you will first have to determine the bank swithcing scheme it uses (there is a document floating around by Kevin Horton which explains all the schemes). Next you will have to build a logic circuit that simulates that bankswitching and controlls the upper address lines that don't come directly from the system. As to the problem of the ROMS having more pins, one way to work around this is to solder a socket of the size of the EPROM into the spot on the cart PCB and let it hang over to the pin 1 side of the EPROM. Most of the pins that match up will have the same function so you will only have to rewire the overhanging pins. Hope this helps Dan

The 20 year figure is also just an estimate. I have seen engineering documents say that EPROMS could last up to 100 years. Also, we are gauging bit rot based on old EPROMS, it's quite possible that newer EPROMS will take even longer to suffer bit-rot. Dan

I actually never thought of Cro§Bow's idea. Forget about my idea, use his. Dan

quote: Originally posted by Jet Boot Jack: Bill - the Shamus sprites move at 1 pixel increments not 4! The data is rotated thru the characters - that's the way I've done it in the past - with either 10 characters each at different data offsets or copying the data into a block of 6 characters or so you can get 100% smooth motion!! sTeVE It appears that in Shamus a sprite has to be fully within a character cell before it can change direction. With this restriction in place it will only take a max of 2 character cells to hold a 4x8 sprite. Without this restriction a 4x8 sprite could potentially appear in 4 characters cells at once. Dan

I took a look at the Shamus display list, it uses ANTIC mode 4. The enemies do move nice and smooth, but they never overlap. I have to say this is a very impressive use of a character mode. Dan

<BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>Originally posted by Cafeman: <STRONG>Dan, I am using VSS .80. Do I need to download a different 'version' of VSS for the debug feature? I will check it out. </STRONG><HR></BLOCKQUOTE> Moderator Edit: The 'debug' version of VSS .80 is located here: http://atarihq.com/danb/ <BLOCKQUOTE><font size="1" face="Verdana, Arial, Helvetica">quote:</font><HR>[QB] Also, Popeye doesn't run in VSs .80 for me - the screen is black but I hear the music. Popeye doesn't run in Atari800win for me either -- it crashes. QB]<HR></BLOCKQUOTE> Maybe you have a bad ROM image for Popeye. I do recal at one time there were some bad images floating around. Dan

For copyright reasons I would be reluctant to scan and post the articles, but a lot of the material in these articles is also in the book De-Re-Atari which you can get here: Moderator Edit: De Re Atari is located here: http://www.atariarchives.org/dere/ Chris Crawford wrote the first 6 six sections of De-Re and some of the sections are verbatim copies of the Byte articles.

If you look at the display list of Joust you will find one DLI at the start, then 2 towards the end. I assume from this that after that first DLI the game simply stays in the DLI for the entire height of the screen, making the sprite position moves as needed. Doing this will each up a lot of processing time, but this wouldn't be a problem with a game like Joust since it has fairly simple game logic and doesn't need the time to do other stuff. If you didn't want to do it this way, you could dynamically alter the display list for each frame and insert DLI's only in the places where you needed them. You can easily determine where different players and missiles are used by using my VSS emulator (www.atarihq.com/danb). The debug version has the ability to turn each player and missile off by pressing keys on the keyboard. Dan

If anyone want's it, here is the Eastern Front source code (I went crazy the other day searching for this). Eastern Front Source Chris Crawford was a master of the Atari 8-bit hardware. He did an excellent series of articles on every aspect of the 8-bit hardware for Byte magazine in 1981/1982 that I still constantly refer to. Dan

Yes, in theory they should work with any system that has a ROM. I have used it with the 7800 and the Odyssey 2, work great on both. The only trick can be building a socketed cartridge to plug the emulator into. For example the eprom emulator I use has a 28 pin connector on it, but O2 carts only take 24 pin EPROMS, so I had to so a little re-wiring to get it to work. Dan