Questions on the Atari 2600's Hardware

[PaultheRoman]

What exactly is missing from our knowledge of the Atari VCS/2600's hardware that prevents us from making a perfect hardware clone of it? I've looked around, and apparently there's already a lot of information, and even hand-drawn schematics, on the TIA custom chip. What else is there missing?

[ColecoJoe]

A lucrative market?

[Keatah]

I don't think it has anything to do with missing information. But, instead, cost and time. And motivation to implement every last detail in a way that makes it compatible with the original.

 

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Further thoughts on this. There are FPGA examples/cores out there for the VCS, which are pretty good, but I don't know how complete they are. Do they output control signals on controller connectors? So that AtariVOX and Sega controllers can be used?

 

And then we have the weird desire to package these replicas in non-standard cases which make operating the system non-intuitive compared to the original.

 

Dare I mention cartridge dumpers which are a complete waste of time?

Edited September 17, 2018 by Keatah

[Keatah]

You may find this thread of interest. It deals with software emulation and how much detail it needs to go into.

http://atariage.com/forums/topic/279643-transistor-level-vcs-emulation/

[PaultheRoman]

Dare I mention cartridge dumpers which are a complete waste of time?

 

What do you mean? Why do you say that?

 

Further thoughts on this. There are FPGA examples/cores out there for the VCS, which are pretty good, but I don't know how complete they are. Do they output control signals on controller connectors? So that AtariVOX and Sega controllers can be used?

 

Can you link me to some of the FPGA cores? That sounds interesting. As for whether they output control signals, I don't know, haven't heard much about Atari VCS FPGA clones.

 

 

And then we have the weird desire to package these replicas in non-standard cases which make operating the system non-intuitive compared to the original.

 

What do you mean by that? I'm pretty sure that the case is not at fault here, if anything it's the lack of a manual, whether printed or in PDF form. Can you show me what it is that your referring to when you wrote this?

 

 

I don't think it has anything to do with missing information. But, instead, cost and time. And motivation to implement every last detail in a way that makes it compatible with the original.

 

If all the information is available, then it shouldn't really be so hard to make a perfect clone of it. Manufacturing aside, it would just be a matter of how much time your willing to spend in gathering all the information needed.

Edited September 17, 2018 by PaultheRoman

[Keatah]

Cartridge dumpers generally don't work with carts that have circuitry beyond the main rom chip. At least that's the situation (now) with the Retron77. It seems to be somewhere around 70-75% compatible. Cartridge dumpers feel cheap to me. All the hard work is done by the emulator developers. All the manufacturer does is build the shell and interfaces. But to be fair, the compatibility level of the Retron77 goes up if you use the microSD card and roms.

 

One core that seems popular is the A2601, it works on the MiST or other similar hardware if recompiled.

http://arekuse.net/blog/tech-guides/fpga-mist-guide/

https://hackaday.com/2010/09/15/atari-2600-recreated-in-an-fpga/

And you should simply do a search on "atari 2600 fpga cores" to get many more links. Some will even link back here to AA.

 

By weird cases I mean mounting the board and its associated in something that precludes having the proper 6-switch available. Some projects rely on on-screen controls or even require you use a controller different than the standard 2-axis 1-button Atari Joystick. Some projects put the cartridge in in non-ergonomic manner or prevent some oddly shaped carts from fitting at all. Some projects may simply not bother with external connectors for controllers and rely on built-in controls - so you don't have the ability to use the keyboard or driving controllers or trak-ball/mouse, or any hacks.

 

There aren't any secrets about the VCS being kept hidden or anything. All the information is there, on the internet. Much of it here on AtariAge. The source code for the FPGA cores is on github. The PCB schematics and TIA internal schematics are available. The sources for Stella emulator are on github. The 6502/6507 is a well-researched and documented chip. The RIOT is pretty straigtforward and still made today IIRC.

 

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So making a clone of the VCS is just matter of bringing all the details together, and doing it in an economical fashion.