56
votes
How did the Atari 2600 achieve a resolution of 160 x 192 pixels with only 128 bytes of memory?
The 2600 didn’t have a frame buffer. Instead, programs running on it had to draw the picture on the screen pretty much in real time.
This actually had some advantages on a low-cost system. Each line ...
- 127k
37
votes
Accepted
How did the Atari 2600 achieve a resolution of 160 x 192 pixels with only 128 bytes of memory?
According to wikipedia, the Atari 2600 had a resolution of 160 x 192 pixels. had it been monochrome, it would had needed 160*192 = 30,720 bits of video RAM, or 3,840 bytes.
Even more taking colour ...
- 231k
36
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 ...
- 37.9k
35
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 ...
- 231k
23
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 ...
- 127k
22
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 ...
- 127k
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 ...
- 10.3k
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 ...
- 231k
19
votes
Accepted
Where did the lookup table in Entombed come from?
Note on the implementation:
This is 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 shifted in to form the next ...
- 39.5k
18
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 ...
- 231k
17
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....
- 231k
17
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 ...
- 1,086
17
votes
Accepted
What does MOS 6507 do in Atari 2600 when you turn it on without a cartridge?
According to the schematics
These are the things on the data bus:
The CPU (which the question is about)
The ROM (which the question posits is not connected)
The RIOT (a.k.a 6532)
The TIA
The RIOT ...
- 39.5k
17
votes
How did the Atari 2600 achieve a resolution of 160 x 192 pixels with only 128 bytes of memory?
The Atari VCS (it only became the Atari 2600, when the 5200 became a thing) is somewhat peculiar, as its video and audio chip, the "Television Interface Adapter", better known as TIA, ...
- 406
16
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 ...
- 1,008
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 ...
- 8,706
16
votes
Accepted
What contemporary hardware was available for the development of Atari 2600 (or other 2nd gen) games?
Since none of those early systems featured any custom designed CPU, generic development systems / In Circuit Emulators can provide all luxury needed.
GI, first of those offered, beside cross-assembler ...
- 231k
15
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 ...
- 3,974
14
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
...
- 1,792
14
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 ...
- 4,977
11
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 ...
- 231k
11
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 ...
- 1,338
10
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.
...
- 37.9k
9
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 ...
- 37.9k
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 ...
- 923
9
votes
How did the Atari 2600 achieve a resolution of 160 x 192 pixels with only 128 bytes of memory?
It seems you think that there is a frame buffer for a full video screen. And that the CPU draws stuff into the frame buffer and some video chip reads out the frame buffer and sends out as video.
But ...
- 35.6k
8
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 (1980) and was ...
- 16.6k
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 ...
- 38k
8
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 ...
- 643
8
votes
Accepted
Is this really an Atari 2600?
It does look like Atari 2600 Jr model, which is smaller, cost reduced version from 1986.
- 2,813
Only top scored, non community-wiki answers of a minimum length are eligible