34 votes
Accepted

What's with the Atari 2600 colors on SECAM?

The TIA manages a very large palette on NTSC and PAL systems because it takes advantage of the way that composite colour is encoded: three bits produce luminance, and the colour subcarrier is always ...
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  • 32.2k
34 votes

How does Space Invaders on the Atari 2600 display all the aliens?

It's rather simple. Neither the multiple sprite mode, nor any secret trick is used. The TIA doesn't have any directly-accessible register for storing a sprite position ahead of time. Sprites are ...
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  • 166k
22 votes
Accepted

Who made the Atari 2600 TIA video chip?

The TIA chips were manufactured by a number of different companies, in a number of revisions over the years; the Atari Compendium’s page on the topic lists: American MicroSystems (“AMI” marking on ...
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22 votes
Accepted

Who owned the rights to the TIA chip?

The TIA was designed by Jay Miner while he was working at Atari. I'd be very surprised if Atari did not hold whatever rights could be held. That being said, the rights that could be held to an IC ...
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  • 7,799
20 votes
Accepted

How does Atari 2600 TIA display multiple resolutions in Asteroids?

There is probably an easy explanation for this based on some facet of how the TIA generates the display. As is readily visible in the image taken from a real Atari 2600 displayed on a modern LCD, the ...
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  • 166k
20 votes
Accepted

Atari 2600 paddle controllers slow, jittery

So I loosely followed the instructions on this site: Atari Paddle Repair (Cleaning Jittery Paddles) Once I had disassembled the "pot" and exposed the metal ring, I could see that the contact points ...
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  • 2,334
19 votes

What's with the Atari 2600 colors on SECAM?

NTSC, PAL and SÉCAM are all colour-carrying signals based on existing monochrome transmission signals. This means that colour information has to be added to the existing monochrome signal, without ...
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16 votes
Accepted

How did the Atari 2600's 6507 handle zero page and stack with only 128 bytes of RAM?

I presume that these locations [Zero Page and Stack] are hard-coded into the workings of the 6502 Yup, they are. So how did this work? Simply by partial address decode. Address bit A8 was not ...
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  • 166k
16 votes

Atari 2600 high voltage output

The Atari 2600 has an unregulated transformer. Transformers of this type only produce their design voltage under load; if you're just connecting a voltmeter between the output wires, it's going to ...
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  • 8,353
15 votes

How do I rip sounds from Atari 2600 ROMs and save it in a more modern format?

Ignoring the copyright issues of such an endeavor, you're going to have a very hard time of ripping audio in a conventional sense. Old games don't store their sound effects and music as waveforms like ...
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  • 908
13 votes

What's with the Atari 2600 colors on SECAM?

There is an explanation listed in the Atari Mania FAQ: Jerry Jessop explains why French Ataris produce fewer colors: I will tell you why it only has monochrome out, because it's SECAM and a ...
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  • 1,682
13 votes
Accepted

What is the history of DE-9 joystick ports?

Two questions, three plus answers. Did this standard have a name? a.1) There is no neutral standard for joystick ports, hence no standard name. When speaking manufacturer/machine needs to be named....
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  • 166k
13 votes

What was the small (cheap) atari-2600 compatible personal computer (not legal) called, that you could program 2600 games, in the 80's?

The Bit 60 and Bit 90, from the company BIT CORPORATION, were said to be able to accept VCS 2600 (hereafter called, simply, VCS) cartridges but there's scant information out there about them. The Bit ...
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  • 2,386
12 votes

What is the history of DE-9 joystick ports?

The DE-9 joystick port is close to a standard D-sub connector (note that it uses the "E" shell and not the much larger "B" shell from the DB-25 serial or parallel port connectors). For joysticks, it ...
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  • 2,865
11 votes
Accepted

How does Space Invaders on the Atari 2600 display all the aliens?

This answer elaborates a bit on the answers by @Raffzahn and @thrust26. The answer by @thrust26 is correct. The alien sprites are not positioned by repeated RESP0 or RESP1 triggers as the code below ...
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  • 891
10 votes

Were some Atari 2600 games written in C?

Moste likely your friend was referring to modern time developments, not contemporary games. While today CC65 does deliver acceptable results for every day jobs, the 6502 isn't exactly C-friendly. C ...
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  • 166k
10 votes
Accepted

Did Atari make more money from arcade games or consoles?

There is a New York Times article (The Game Turns Serious at Atari from December, 1982. One quote from it is: Atari is also facing problems in its two other businesses. Its arcade game business has ...
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9 votes
Accepted

Is it possible to bend tension back into Atari 2600 joystick contact domes?

TLDR; Yes you can bend them, don't bend them too much and don't flatten the dimples. First be sure the contact disk is the issue. If the problem is intermittent, You can also remove power from the ...
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8 votes

Atari 2600 high voltage output

The design of the Atari 2600, and many other devices that use "9-volt DC" wall bricks, doesn't really care about receiving exactly 9 volts, subject to a few constraints: The voltage must be far ...
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  • 26.3k
8 votes

What causes the horizontal lines at the left of the Atari 2600 screen?

Each moveable object on a 2600 is handled by an individual counter. Each counter has the same period as the width of the display and triggers a new output of the object when it wraps around. ...
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  • 32.2k
7 votes
Accepted

Fastest way to write 0x00 to a zero-page memory location? (6502, Atari 2600)

My second bite of the cherry: another of the undocumented opcodes is SYA/SHY/SAY which will: AND Y register with the high byte of the target address of the argument + 1. Store the result in ...
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  • 32.2k
7 votes

Who made the Atari 2600 TIA video chip?

There were 12 different versions of the TIA, and it was manufactured by a whole host of different manufacturers, some of which are well-known. The manufactures included AMI, Synertek, Motorola, and ...
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  • 56.5k
7 votes
Accepted

Recommendations for high quality cheap RF demodulator

Although a VCR would have worked, I couldn't get my hands on one for free and I wanted to avoid the amount of space it took up. I ended up grabbing some mystery units they were throwing away at work. ...
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  • 441
7 votes

Were some Atari 2600 games written in C?

Only people who worked for Atari or third-party game developers could say for sure. For early development, the history of the 2600 and C don't align very well. Atari began design for the first ...
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  • 633
7 votes
Accepted

Is this really an Atari 2600?

It does look like Atari 2600 Jr model, which is smaller, cost reduced version from 1986.
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  • 1,750
7 votes

What is the first documented instance of video game console "Frying?"

I think it would be unlikely to work on computers, as opposed to consoles. The trick relies on corrupting values in RAM (by disrupting the DRAM refresh cycle) without also corrupting the game code; ...
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  • 16k
6 votes

What is the history of DE-9 joystick ports?

From what I can see on the Wikipedia page about the Atari Joystick Port, it seems that the whole "cross platform" standard of the DE-9 joystick started with the VIC-20 (1981) and was followed by the ...
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  • 14.1k
6 votes

Where did the lookup table in Entombed come from?

So: what's the core idea of this algorithm? It looks like some variation of a linear-feedback shift register. These look at some of the bits in the value, and then produce another bit which is ...
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  • 33.6k
5 votes

How do I rip sounds from Atari 2600 ROMs and save it in a more modern format?

I'm going to chance my arm that there's no automated solution because there's no [realistic] automated way to find and trigger all the possible sound effects. You're probably going to have to be a ...
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  • 32.2k
5 votes

Atari 2600 shows no signs of life when power is applied?

If the power led doesn't turn on, your first suspect is the voltage regulator, as you have spotted. It's a very common one, 7805, easily found. For any repairment attempt, however, it is very ...
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