DanBoris
-
Content Count
1,086 -
Joined
-
Last visited
Posts posted by DanBoris
-
-
Ok, since I did a partial disassembly trying to resolve the Food Fight easter egg mystery, I decided to dig into the disassembly further and figure out the rules for instant replays. From my examination of the actual program here is what I see:
As some people mentioned above it mainly has to do with having only a little time left on the cone (you can't leave the level in less then 12 seconds), and having a certain quantity of "close calls" with the chefs. There are also restrictions on which levels it can happen on and how often it can happen. Replays can happen on levels 5-17, 100-499, 600 and up. Seems like an odd set of numbers but that's what the code says. Also once you get a replay you have to wait for 5 more levels where you didn't leave the level early before you will get another replay.
Dan
-
Also the team, like a lot of emulator authors, have to deal with a lot of clueless and even downright ignorant people and this can really wear on your nevers.
nevers?
I only said I was an emulator author, I never claimed I could spell.
-
Well, I find most of the hate is towards MAMEDEV. They have been accused of egotism, elitism and some rather shady dealings. Not to mention the EMU drama that the group tends to get. Stuff like that sucks the fun out of MAME unless you nothing of the drama around MAME.
I've been part of the MAME development team for many years and although there may be a case here and there where "egotism and elitism" may occur, in general I find it to be a very good, easy to work with group of people. For the most part everthing the team does is to serve the goals of the project. Unfortunetly these oftern conflict with the interests of the people using MAME just to play the games. The ROMS not working is a perfect example. MAME always tries to support the best know set of ROMS so it can always be used as a reference for what the correct roms are. By not supporting incorrect roms, it encourages people to get rid of these bad roms sets (althought this often doesn't happen).
Also the team, like a lot of emulator authors, have to deal with a lot of clueless and even downright ignorant people and this can really wear on your nevers.
Dan
-
"The general consensus is the 7800's architecture is essentially just an Atari 2600 with a slightly better CPU, more system RAM, and an advanced graphics chip (MARIA). "
That is a pretty stupid statement. If you say the systems are the same except for the cpu, RAM and graphics chip, what else is left!
Of course the beauty of Wikipedia is that we can change that statement if we like. Any suggestions on what it should say?
-
Got a few Q's about the 7800 hardware:
- Does MARIA drive A11-A15 when doing DMA? E.g. could video data be read out of ROM?
Yes, graphics data can, and usually is, stored in ROM. The only thing that can't be in ROM is the display list due to access time requirements, although it usually doesn't make much sense for this to be in ROM anyway.
- What does the DE pin (pin 9) on the MARIA chip do? Does it have any relation to the TIA DEL pin (pin 10)?
Yes, this appears to be the color delay input just like the TIA has. In the 7800 it's hooked to the same circuit as the TIA DEL pin.
- When the BIOS ROM is enabled, is it mapped to the $8000-$FFFF range? Docs say $F000-$FFFF but it looks like the output latch and A15 are all that's used.
Yes, it appears that the BIOS ROM is enabled in the whole address range from $8000-$FFFF. In a NTSC 7800 the BIOS ROM is located at $f000-$FFFF which is where it is designed to run, but it is also probably mirrored through the rest of the range. PAL 7800 have the Asteroids ROM in place of the BIOS which runs from $C000-$FFFF.
- The MARIA and TIA video busses are combined in an OR latch. Considering the TIA video registers are not accessible when 7800 mode is enabled, could meaningful video data be programmed in the TIA (say the 20-bit playfield registers) and then switch modes to have the MARIA video combined with the TIA display?
It may actually be possible to activate both video siganls at the same time but the problem is that both the Maria and the TIA generate thier own video sync signals, so unless these signals where in sync with each other it would freak out the TV and you wouldn't get a usable display.
- I assume the RIOT RAM is fully accessible and functions normally as expected? Or did Atari not advise 7800 programmers to use it, and it was for 2600 compatibility only?
- Somebody mentioned the timer component of the RIOT loses cycles. I assume this is due to the phase 2 clock generated by MARIA getting slowed down during TIA register access?
Yes, it is a fully functional RIOT chip, but when you access it the system clock is slowed down to 1.19Mhz which is why the Atari documentation recommends not using it for anything but IO. The timers would have limited usefulness since the mix of fast and slow clocks would make it hard to get an accurate time out of them. Not sure why they don't want you to use the RAM.
Dan
-
I saw this on a newsgroup in response to a question about I/O Error on Arkanoid:
Check to see if maybe one of the coin switches are stuck.
If one is stuck, the game will lock up at power up with the
"I/O Error" message. If this is the case, clearing the stuck
coin switch should take care of your problem.
Hope this helps.
Dan
-
dan, we call this "random map generator" as it is based on random algorithm which is fed by seeds so you can recreate the levels each time again... --> diablo 1+2...
or nethack...or rogue...I just took a closer look at Telengard and it doesn't use a random number generator. Here is the pseudo code for it's map generator:
Q=X*1.6915+Y*1.4278+Z*1.2462+X*1.4278+Y*1.2462+Z*1.6915: HI = Q AND 255 Q=X*Y*1.2462+Y*Z*1.6915+Z*X*1.4278 IF Q & 0x03 != 0 THEN Q = (Q >> 2) AND 0x0F If Q > 9 then Q = Q - 9 HI = HI + (Q << 8) HI=HI+Q*256 END IF HI = INT(HI)
X, Y, and Z are the room coordinates in the maze. Each level is 200x200 and there are 50 levels. The value of HI defines each room as follow:
bits 0-1: Top wall, 0 = no wall, 2 = wall, 3 = door
bits 2-3: Left wall, 0 = no wall, 2 = wall, 3 = door
bits 8-15: Special items, Inn, Pit, Teleporter, Starway, etc.
Dan
-
-
Yes, this sounds very similar to how Telengard does it.
In this game, the maps are randomly generated but are the same each game. The game uses an (ugly) random number generator to compute the sequence of random numbers. If the seed is the same, the sequence will be the same. That's why the maps are the same each game, but are programmatically generated 'randomly'. That's why the first step of this reverse engineering was to write the same random number generator the game uses. A good way to have a different sequence every game, is (generally) to use the clock as seed. But the developpers wanted fixed seeds to let the player learn the dungeons and choose the good and bad ones. The lack of memory prevented to store all the dungeons (9k per dungeon). So they've done a random map generator using fixed seed.
Does your word 'mathematically' mean the same thing ?
edit: spelling
-
Do you plan to release the source code for this? I would be really interested to see the algorithm.
I have been studying the game Telengard recently and it has a really interesting way of generating it's map. The map in Telengard is huge, 50 levels with 2,000,000 rooms, but it doesn't generate if randomly. It has a clever little algorithm that generates the map mathematically so that it's the same every time you play the game.
Dan
-
You don't need inverters for the 5200 cartridge to use a standard eprom. Unlike the 2600, the 5200 has active low chip enablee. If you need it the schematic for the cart can be found on my page:http://www.atarihq.com/danb/a5200.shtml] http://www.atarihq.com/danb/a5200.shtml[/url]
Dan
-
Now I guess I'll spend the better part of the day looking through all my roms seeing what other messages if any I can find
Kenny
No need to, check out this thread:
http://www.atariage.com/forums/index.php?s...c=83980&hl=
although I must have missed Millipede since that not on my list.
Dan
-
According to the Internet Pinball Machine Database
http://www.ipdb.org/search.pl?any=solar+ri...earchtype=quick there where two versions of Solar Ride, one was electro-mechanical and the other was solid state. If the machine your looking at has digital score displays then it's a solid state one.
Dan
I have been looking for a good and inexpensive pinball machine for years now.
I have been offered a Gottlieb 1977 Solar Ride for $550.
It is close by and the seller has restored it and it is in good working condition.
This guy seems to have a LOT of pinball machines and seems to sell quite a few around this price.
This is the lowest I have ever found a working Pinball machine.
It is still a huge chunk of change for me, so I would like to know two things...
1) Is this a good deal?
2) I think it's electro mechanical although it has a digital display... if that makes sense... how hard are these to maintain?
-
Love: Getting more fuel by shooting a fuel tank (e.g. Scramble/Super Cobra)
Dan
-
WOW...that is awsome! And exactly what I was looking for.....Haunted house was my favorite! Thanks!
I totally forgot about Haunted House, I distinctly remeber playing that one back in the day!
There was another electro-mechanical I remeber playing alot, which I have never seen on the net. It was a firefighting game where instead of a gun you would control a water nozel that would spray real water at a building at the back of the machine. The windows of the building would light up as if on fire and you would have to direct the water nozel at that window. The game even had a hand operated windshield wiper to clean the front glass of the machine.
Dan
-
Umm.. all computer and videogame systems use some off the shelf components. The entire graphics and sound system plus part of the IO for the 2600 was in a custom IC.What do you think of this...
"Atari initially threatened clone producers with lawsuits, and actually sued Coleco over its 2600 module and Gemini clone. However, since the 2600 contained no patented material and was made up of all "off-the-shelf" hardware (and no copyrighted software), the company evidently realized litigation was futile. Coleco and Atari settled out of court, and many other companies quickly came out with their own 2600 clones, some of which are still made to this day."
That was from http://www.classicgaming.com/museum/2600/ and I've read similar things many times in many places. It's some huge misinformation campaign?
Edit: Some more research shows that perhaps this is misinformation, stemming from the fact that early Atari 2600 clones were made from entirely off-the-shelf parts. I know the Gemini board is *very* busy looking compared to a real 2600's.
Edit #2: Found one of my Gemini boards, and it had only three chips - the 6507, the 6532, and a custom one labelled "Coleco 73192 E4002", manufactured 8307. I'm pretty sure older Geminis had near a dozen ICs, so I guess they later integrated them to save costs, once they had settled with Atari?
The TIA chip in the 2600 that handles video, sound and some IO was definitely a Atari propritary part and not an "off the shelf component". Incorrect information has a tendancy of spreading from one web site to another, this doesn't make it correct. I am not sure if Atari held a pattent on any of the TIA technology at the time of the lawsuit with Coleco.
It's unlikely that the clone machines, like the Gemini, used off the shelf parts instead of a custom IC, since it would take dozens of standard logic chips (I would bet a 100 or mote) to re-create the funtionality of the TIA.
Dan
-
Hi,
I am interested in writing a disassembler for the Atari 7800. I have never done anything emulator-related before, and I am having trouble finding documentation.
Thanks,
Nick
Most 7800 ROM images start with a special 128 byte header (see below) that was not part of the original cartridge. The remainder of the ROM image is just a straight dump of the binary data in the cartidge. There is nothing that seperates 6502 instructions from graphics or other kind of data. The only practicle way to do this is to create a tracing disassembler that traces all the possible execution paths through the code and marks them as code, so what remains after the tracing is the data.
Cart Header:
To work with this emulator ROM images must have this 128 byte cart header at
the start of the raw data. This header allows the emulator to know the features
of the cart thus preventing you from having to use a bunch of command line
options.
0 Header version - 1 byte
1..16 "ATARI7800 " - 16 bytes
17..48 Cart title - 32 bytes
49..52 data length - 4 bytes
53..54 cart type - 2 bytes
bit 0 - Pokey cart
bit 1 - Supercart bank switched
bit 2 - Supercart RAM
55 controller 1 type - 1 byte
56 controller 2 type - 1 byte
0 = None
1 = Joystick
2 = Light Gun
100..127 "ACTUAL CART DATA STARTS HERE" - 28 bytes
-
If you are trying to run VSS under windows XP, you will probably need VDMSound (http://sourceforge.net/projects/vdmsound/) to make the sound work properly.
Dan
-
There was a site that was doing basically that, Starroms, but unfortunetly they in-explicably closed up shop earlier this year, don't know if there was ever a public explination of why. Hopefully someone else will attempt this, since I agree with you selling old roms at a low cost would probably generate a lot of business.
Dan
I imagine right now the DRM issues are the problem. I bet someone is working on a solution right now. But if they're not, they should be. First person that does that is going to corner the market. If you price the roms reasonably and make up your money on gross sales, it will succeed.
I don't know that you would even have to bother with DRM. Since all these ROMS are already floating around out there on the net and are quite easy to find, there really is no point in protecting them with DRM, if someone really wants a copy for free they don't need to get it from the guy who downloaded it from a legitimate site, they could just get it off another site.
Also, I think it would be hard to come up with a DRM scheme that was permissive enough to allow you to play the game as you wanted to. Atari 2600 emulators for example run on a ton of platforms, PC, Mac, Linux, Dreamcast, GP2X, etc. It would be hard to come up with a DRM scheme that would work across all platforms.
Dan
-
Ok. Now you're saying something a lot different than your original post, and I can completely agree with this. I've been saying for awhile that someone needs to start an iGames site where you can download legally licensed ROMs with DMRs built into them.
Hey... if you're part of the development team, and you want to do something to encourage the manfuacturers to get on board... there you go. Push to have DMR incorperated in the ROM format, even if it means a complete overhaul of the ROM encoding method.
You do that, and you get the manufacturers selling their titles for $.99/rom, you'll have a legitimate business model that will make them tons of money. It is a matter of WHEN... not if... and MAME might as well be the one that innovates the standards...
There was a site that was doing basically that, Starroms, but unfortunetly they in-explicably closed up shop earlier this year, don't know if there was ever a public explination of why. Hopefully someone else will attempt this, since I agree with you selling old roms at a low cost would probably generate a lot of business.
Dan
-
I don't know anything about that specific site, but if these people have no problem breaking the law in selling something like this, they probably wouldn't have a problem ripping you off, and if they did you would have no re-course since you are buying something illegal.Dan
These guys are often *every* bit as comitted and genuine in their passion for MAME as any hardcore retro collector here on Atari Age. The guys who copy MAME sets on DVD as a service often have a policy page, and you can get a feel for what drives them by reading this.
Almost ANYONE doing this is doing it as a passion, not as a business, and certainly not to get rich. I think it shows a tremendous lack of understanding to assume that they're "breaking the law" for monetary gain. As far as I've ever seen, most of the people who do this probably lose money in the long run.
Trust me, as a member of the MAME development team, I understand the situation. Yes, you are correct not everyone is doing this for monetary gain but there are some that are. The MAME team has contantly had to battle with people who abuse MAME for non-legitmate commercial purposes. People who sell ROMS of disks and associate these closely with MAME by using the MAME name, or actually including MAME along with the ROMS (which is against the license), put MAME in a very negative light and may drawn the attention of the copyright holders. The MAME team does everything it can to protect the original goals of the project which are to document and preserve these games. They also support legitimate projects that secure legal rights to the games, in the hopes that more companies will allow thier games to be re-released in a legal manor.
Dan
-
I was looking around on the internet and I found some sites that allow you to buy around cd's/dvd's with a complete set of MAME roms on it. I found this site, http://www.freemame.us/shop/index.php?productID=121. I was wondering if this is a good site and any other info people can give me on this idea? Thanks.
I don't know anything about that specific site, but if these people have no problem breaking the law in selling something like this, they probably wouldn't have a problem ripping you off, and if they did you would have no re-course since you are buying something illegal.
Dan
-
How much is one of these machines worth? From what I understand, its a predecessor to Space War from 1968.
I saw a mint condition one go at an auction earlier this year, and although I can't remeber the actual selling price I don't think it went for over $200.00.
Dan
-
Another good arcade close to New Jersey is Challenge Arcade in the Berkshire Mall (located near Reading PA, in the town of Wyomissing). When I walked into this arcade it was like stepping back into the 80's! They have a good number of classic arcades and pinball machines (as well as some newer games), and they are all in excellent condition, the operators obviously take good care of thier machines. You can get more information and see some pictures here:
http://www.classicarcadegaming.com/locations/ca/index.htm
Dan
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
my unofficial Sally questions thread...
in Atari 7800 Programming
Posted · Edited by DanBoris
The halt line is not actually visible to the software running on the cpu. The halt line simply stops the 6502 clock in synchronization with the instruction cycle, and tri-states the data and address bus so that the MARIA can take control of the bus.
Dan