Atari 7800pâ„¢

S q u e e ! · Post by **S q u e e !** » Wed Dec 14, 2005 6:47 pm

I am now officially going to attempt making the first ever Atari 7800 portable. I have been looking for more info on the system, but I was wondering if this would really be the first or not. Feedback?

Lucretius · Post by **Lucretius** » Wed Dec 14, 2005 7:19 pm

As far as I know, it would be the first. Beware though. The 2600's portability comes from the hackability of the mobo. As far as I know, the 7800 don't got dat!

Post by **Sparkfist** » Wed Dec 14, 2005 7:44 pm

The 7800 motherboard is HUGE!!! Good luck on that because one member thought about it but gave up when non of use could see anything that could be dropped.

timmeh87 · Post by **timmeh87** » Wed Dec 14, 2005 9:04 pm

you COULD map out the traces between ALL the parts, put it back together in a PCB design program, and make yourself a smaller custom mobo. i mean... its POSSIBLE

someone · Post by **someone** » Wed Dec 14, 2005 9:57 pm

timmeh87 wrote:you COULD map out the traces between ALL the parts, put it back together in a PCB design program, and make yourself a smaller custom mobo. i mean... its POSSIBLE

That was my first thought... and then I saw this!
http://www.atari7800.org/schematic.htm
That thing has a lot of stuff on the motherboard.

Reaperman@home · Post by **Reaperman@home** » Wed Dec 14, 2005 10:01 pm

I'm trying real hard to think of a game that was more fun on atari 7800 than any other far easier atari system... Ballblazer? It was a *darn* good ballblazer, I guess...

I suppose the real up swing is that you get to redesign those controllers.

edit: and well, I forgot about that 'masterblazer' game on the 16-bit computers. That was way better then the 7800 ballblazer...

S q u e e ! · Post by **S q u e e !** » Tue Jan 03, 2006 7:02 pm

Well, an update is in store. I found two things.

1) Atari 7800 Video mods

and

2) The Atari this will be performed on

Sorry to drag up this *really* old thread, but I decided it needed to be updated

Zhooibaal · Post by **Zhooibaal** » Wed Jan 04, 2006 3:53 am

I would also be possible to create a multi layer custom motherboard. I mean, it's possible to chop up the design into smaller parts and create those seperately, then interconnect the smaller parts with wires and put that into a portable casing. It still would be quite big because the space you save on the surface, you will gain in height, because fitting it all directely together will even be more complicated if not impossible.
Anyway, it would be a heck of a job to get it small enough.

S q u e e ! · Post by **S q u e e !** » Mon Jan 16, 2006 7:51 pm

Ok, I now have a system to operate on, 4 contollers to test, and 43 games to play when I am completed. I have some basic pinouts, but I now have a question for all of the tech geeks out there:

So, each "button" (really three traces leading to a central point) is "pulled down" when you press it. There are quite a few pins on the board itself, and I have a question regarding them.

When you look at the board with thetraces facing you, there are colored wires coming from the bottom, going to the triggers, and then heading for the connector at the end. There are 7 wires on the main PCB: Green, Red, Blue, Black, White, Yellow, and Brown. Each wire has a trace that connects it to a specific part (duh!), but there is a mystery cap that has its own trace from the right direction button that leads to Black (which I am assuming is Ground). This cap is black in color, appears to be made of plastic, and has no visible markings indicating how many uFs it carries (if it even is a cap). Do you suppose this is just a jumper of sorts, or could this be something dreadfully important?

**EDIT**

Maybe I should add that there are two 720Mohm resistors on the board; one between Ground and red, and one between ground and yellow, can these be removed at any time when I redesign the controller (I will be using a PS2 joystick like the CNC built Atari from Ben's book) and replaced with 4.7kohm resistors like in the book?

Post by **Skyone** » Mon Jan 16, 2006 8:24 pm

Just to add to it, the whole idea is very possible, but large! I mean, that mobo is as big as Shaq's feet.

elliott · Post by **elliott** » Tue Jan 17, 2006 12:49 am

S q u e e ! wrote:This cap is black in color, appears to be made of plastic, and has no visible markings indicating how many uFs it carries (if it even is a cap). Do you suppose this is just a jumper of sorts, or could this be something dreadfully important?

Maybe I should add that there are two 720Mohm resistors on the board; one between Ground and red, and one between ground and yellow, can these be removed at any time when I redesign the controller (I will be using a PS2 joystick like the CNC built Atari from Ben's book) and replaced with 4.7kohm resistors like in the book?

If I remember right the "cap" as you call it is a diode, I can't really remember though. I think it needs to be there. Test it for continuity, and resistance, it is probably just a jumper.

I do know that the two resistors need to be there. They are for backwards compatiblity to one button games. I think they can be anywhere from 400ohms to 800ohms, but they must be the same. I used 620s when I made my two button WICO and NES controllers.

This may help:

Code: Select all

7800 control (buttons)

                                       /----------YLW(-) pin 9
                            Button L  /
                      /---------()---| YLW splits
                     /                \----/\/\/-----\
pin 6 ORG(+) -------| ORG splits           520 ohm    |---BLK(-) pin 8
                     \                /----/\/\/-----/
                      \---------()---|     520 ohm
                           Button R   \ RED splits
                                       \----------RED(-) pin 5

S q u e e ! · Post by **S q u e e !** » Tue Jan 17, 2006 9:41 am

Thank you!