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30

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 exactly the same sinusoid, but four of the other colour bits set its phase. So for both NTSC and PAL: three bits set the amplitude of one signal; four bits set ...


30

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 drawn when they are enabled on the actual line (Y coordinate) and whenever RESPx is triggered (X coordinate). To display the 6 aliens, RESPx gets triggered 6 ...


21

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 the TIA) IMP Intersil MA (it’s not clear which manufacturer this is) Motorola National Semiconductor OKI Semiconductor Synertek TSU United Microelectronics Corp ...


20

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 vertical resolution of the score area (where you see "13") is higher than the vertical resolution of the game play area. No, it isn't. Atari 2600 [...] is ...


20

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 disturbing it (or as little as possible). The missing information is represented as red and blue differentials with regard to the luminance. NTSC and PAL carry ...


15

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 read significantly higher than the output rating.


15

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 were caked in 35 years of black gunk. Using a Q-tip and a light amount of rubbing alcohol, I was able to clean the contact points, being careful not to leave ...


14

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 decoded when RAM was accessed and A7 was used as chip select. This mirrored the 128 ($80) bytes two times over ZP and Stack (at $0080 and $0180) (*1). So all 128 ...


14

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 modern PC and console games do. This is because both the audio hardware on old computers and consoles was much more limited, and because there wasn't enough ...


13

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. a.2) There is a standard for the connector used by most 8 Bit machines, as their DE9 is part of the series Cannon developed in the 50s. Here D is the general ...


12

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 SECAM GTIA was never produced. The PAL GTIA is used in France and the Lum outputs are run into an onboard encoder to produce a "psudo" color depending ...


12

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 was first used an the Atari 2600 VCS, went on to their early 8-bit machines and was then adopted by Commodore.


9

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 does require a certain memory handling - and quite some RAM as well. To program the 2600 with its bare bone 128 Bytes of RAM is already a tough job in Assembly ...


8

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 enough about 5 volts to allow a cheap regulator circuit to convert it into 5 volts. There is an upper limit which will cause essentially immediate damage--typically ...


7

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 National Semiconductor. This article has lots of details, including pictures of the many versions of the TIA IC with many different manufacturers' stamps.


6

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 prototypes of the 2600 began in late 1975, shortly after the 6502 was introduced. C made its first appearance anywhere in 1972 and Kernighan and Ritchie wouldn't ...


6

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 Atari and spray plastic safe contact cleaner into the controller socket and system pins and then insert and remove several times to clean up those connections. ...


5

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 C64 (1983) and Amiga (1985) computers as full implementations. There were others which were mostly compatible such as the ColecoVision (1982) and Sega Master ...


5

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 human who plays for long enough to figure out how to trigger all the sound effects, in which case you almost might as well have captured them when you play. Given ...


5

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 advisable to have, at least, a multimeter. With it, you can see whether the 7805 receives voltage input (left pin), whether this voltage is enough for the regulator to ...


5

C didn't have anywhere near the popularity and ubiquity that it does today. As has been mentioned elsewhere, the 6502 is a crummy target for a C compiler, notably with it's sparse, 8 bit register set. Recall the sparse architecture of the machine: 128 bytes of RAM and 4K of ROM. A 4K assembly language program, with several 8-bit, and a few 16-bit counters ...


5

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 memory. If you were willing and able to switch your usage of X and A then you could have 01100000 in X, therefore the argument you supply to SAY would be 001b - ...


4

On the 2600 vertical resolution — the number of unique pixels shown in a column — is the game author's choice. It can be anything less than the upper bound imposed by the video signal. The 2600 has no DMA. It's TIA video chip cannot fetch anything. The entire display is push. The CPU pushes a new line of background and/or it pushes a new line of sprite data ...


4

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. At a glance I was optimistic they'd do what I needed, and I turned out to be right. I grabbed a 232-MTA S12 Mono TV Tuner box made by Contemporary Research. ...


3

The Atari 2600 needs to go through an RF modulator before it will display any video or play any audio on your TV. You mentioned that you have an coaxial adapter. Some of those adapters actually do a good job separating the audio/video signals. Some, are just pass-throughs and aren't suited for real RF modulation. If you have an old RF modulator box like ...


3

Regarding the "only 8 colours" point, these are the standard colours available with RGB controls when the only choices are to turn the red, green and blue channels either on or off. Running through the truth table for the options available:- red off, green off, blue off: black red off, green off, blue on: blue red on, green off, blue off: red red on, green ...


2

We used to replace the domes with half razor blades (split in half along the long side). The blade can be attached in the center, below the metal ring, and right there you can put a little bit of paper to lift it up. It was a lore more 'loose' than the original contact dome, but it was durable.


2

Many old systems don't have sounds in the way you think of them. Instead, the game has several pre-recorded notes (recorded as in written by hand, probably not more than a byte or three), which the game or program can use in succession. To get these notes, I suggest using TheSoundsResource. Keep in mind that what you're doing may have copyright issues, as ...


1

Perhaps Anthony Henderson? AtariAge says he worked at Atari circa the 2600, and worked on Graphics there.


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