Poll: Better graphics -- Hardware upgrade development

[TMR]

I think it's related to the DMA of the video chip. Though the Video chip has its own bus, it does need it fulltime on graphics fetch. The CPU isn't halted, so could write (via the control-registers and ports) to the VRAM (the video chip's own RAM) which leads to a bus conflict.

 

Yup... right pain in the arse. =-)

 

Have you ever looked at some code of a NES game? It has a NMI vector on $FFFA so it certainly has a VBlank (or similar) interrupt.

 

i've never looked at other people's code, i prefer to just launch myself ata machine and see what i can do. $fffa is the vblank, $fffc is the cartridge warm start and $fffe is NMI.

[analmux]

I've got a little problem.

 

I don't know if I'll be able to provide the video upgrade boards. Jetboot Jack (who lives in Silicon Valey) said he knew a factory or something that can produce boards, and he can provide NEW (both PAL/NTSC) ANTICs and GTIAs. I don't know if he can still help me with the project.

 

Another problem: It could be too expensive, and there's a risk that there won't be any developing of games/progs for it.

 

Yet another problem: I'm a bit depressed by some words of certain people on this board. Why would we even bother to upgrade the video. So I don't even know if I'm enthousiastic about working on this project anymore.

 

The only thing I'll do in some time, after my big forum break, is post some schematics, with which all other hardware freaks can build it too. Then we'll see what happens.

 

I don't have an atari-dealer in my neighbourhood, and I've got too little money to invest in this, so I'll freeze the project now.

 

So, I'm very sorry to say this.

 

-----

mux

[andy_bernstein]

@ analmux

 

I'm located in Santa Monica so it's easy for me to deal with B&C / Best and they tend to be my primary source for parts. If we work out a large order, we could probably get a better price that usual.

 

Don't let go of your project, I'm very interested ! Once Patrick F. is done with my 130XE, your video upgrade board is my next purchase so that I can program for it.

 

Buzz me with a PM if necessary.

 

Air France KLM... sounds like a good idea (hopefully).

 

AB.

[Thelen]

I've got a little problem.

 

Sad to hear , but I understand your point.

 

Thelen

[analmux]

Okay, I'm finding new inspiration to go on with this. :wink:

 

I suppose I needed the break to concentrate on the lovely girl I met three weeks ago.

 

Andy Bernstein offered me to help in the development, and I would like to go on.

 

I only have to say that I'm not doing a fitting service personally, but only design and testing of betaversions of the video upgrade board.

 

I hope a lot of other hardware freaks around the atari world will love to build the upgrade themselves, or for others.

 

Our task is to produce the board:

Parallelbus device/Cartridge or internal board.

 

The fitting service should consist of mounting a small 15 pins (lpt-like) connector in the backside of the Atari case, and soldering about 15 wires inside the Atari to make the LUM0-3 multiplexing possible. That's a really small job, like making a SIO2PC interface. That should be do-able for do-it-yourself hardware hackers.

 

Okay, that's it for today. I'm waiting for some response from A.B.

 

-----

mux

[andy_bernstein]

Hello Analmux,

 

Yep I'm back - been busy these last few days. I got a brand new soldering iron from Fry's this morning + I'll get the chips from my source.

 

Having said that, I do NOT have any PAL system here in California. If somebody wants to donate a PAL Machine or Board (800XL would fit the bill perfectly), it would be much appreciated.

 

Thanks.

 

AB.

[andy_bernstein]

A Quick note to let everyone know that this project is still very much alive in my heart. As soon as time and money are available, it will be my next priority to work on.

 

AB.

[carmel_andrews]

Didnt Bob Wooley try this one out 'successfully' at the back end of the 80's, i do remember this because it was mentioned in Atari User and/or page 6, chuck steinmann tried something similar with pokey, hence the original pokey stereo upgrade 'gumby'

 

I cant remember the exact spec's of the unit he did, all i remember is that it did 4096 colours/colors (a'la Amiga/ste)

 

someone on one of atariages forum mentioned the c65 from cbm which used an upgraded/updated vic2 chip called vic3, it too had high rez modes and amiga/ste style colour/color range (4096 colours)

[+AtariNerd]

:::stirs the pot:::

 

I know it's been a good while, but any further tinkerings? If we get enough of these projects going, maybe one will....

[+bob1200xl]

 

Here is a dual ANTIC hack. You basically switch in one or the other ANTIC/GTIA pairs and load screen data in normal Atari fashion. Then, you switch to the other and load its data. The two GTIAs outputs are then mixed to give lots of colors and such.

 

 

 

 

Here is a wiring diagram in case you want to build one...

 

 

Bob

 

 

:::stirs the pot:::

 

I know it's been a good while, but any further tinkerings? If we get enough of these projects going, maybe one will....

[+bf2k+]

 

Here is a wiring diagram in case you want to build one...

 

I can't find a pencil!

[+AtariNerd]

Well, I better start working on my soldering skills, then. Maybe after a few years I might get something that won't be a hazard to those I love and care for.

 

Don't want anyone to think I was trying to be snarky. I do appreciate all the things that you creative folks do- know it's done out of your love for the hobby and with your other commitments, it is difficult to find time to do all that you might wish. I would be unlikely to accomplish even a half of what the wizards here are able to. Just like to tease and goad (kindly), get the ideas out there and flowing.

[ClausB]

Here is a wiring diagram in case you want to build one...

Very nice.

 

I notice, however, that if you move the wire at IC3-11 to IC6-26 and XOR IC2-4 with IC12-15 through an RC network with time constant 47 ns, then you can avoid the skew between ANTIC's phi2 falling edge and GTIA's color phase delay reference, providing a more stable horizontal sync signal for advanced interlaced or component video applications. See what I mean?

[+bob1200xl]

Oh, yeah... I was going to consider thinking about that.

 

What I do see is that it's not a good idea to post anything on April 1st!

 

This really is a dual ANTIC/GTIA. I think it's a drop-in except for the fifth LUMA bit that gives you 32 shades of a color. Not sure it's worth it but it does look continuous when you stack them in order. (after you tweak the resistors a little)

 

I found this while I was looking for joysticks. There really isn't much logic involved - thought I might make a board with a CPLD when I get done with this CPU stuff.

 

Bob

 

the horizontal sync...? I kinda deleted that to free up some ANTIC cycles. That's hard for you to trace out, I know, with all blue wires. I started using multi-colored wire after this project!

 

 

Here is a wiring diagram in case you want to build one...

Very nice.

 

I notice, however, that if you move the wire at IC3-11 to IC6-26 and XOR IC2-4 with IC12-15 through an RC network with time constant 47 ns, then you can avoid the skew between ANTIC's phi2 falling edge and GTIA's color phase delay reference, providing a more stable horizontal sync signal for advanced interlaced or component video applications. See what I mean?