7 replies to this topic

[Longhorn Engineer]

This summer I am going to be working on the 5200 mod. I talked about this new idea I had at MGC and I want some input on it. The idea will be to basically convert the chroma signal to digital via a 8bit video ADC. Run this and the Luma to a microcontroller. I am thinking the propeller chip as its fairly cheap and is very flexible. From here its all code and the Propeller chip can be set to output composite, s-video, RGB (i think), VGA. The PCB will have all the footprints and pinouts and the video mode will be set via jumper. With the MC the timing between the signal should be very easy to dial in.

[wood_jl]

Well, if you could make it also work in the Atari 400, that would be cool. The 400 is the bastard child that nobody cares about. As the fledgling low-boy of the line, I think it's really cool to have one with 48k and WOULD BE cool to have a monitor port - or maybe just S-video and composite/sound jacks.

From ANTIC magazine, April 1983 "New Products:"

Quote

XTRAVIDEO 1
(video monitor output)
HARDSEL
P.O. Box 565
Metuchen, NJ 08840
(800) 835-5465
$39.95

This is a plug-in video monitor output module for the ATARI 400. No soldering is required. It uses a standard RCA phono plug and is compatible with most monitors, including the BMC 12.

As I doubt this is going to happen for the lowly bastard 400, anybody know where to get one of these?

[5-11under]

This is the way of the future, I believe, especially if you consider digital outputs such as DVI.

First of all, I must say that I'm not too clear on how the 5200 derives colour. If it's similar to the way the 2600 does, then I'm still not too clear on how the three(?) chroma outputs work together - are they all analog, or is just the luma that is analog, while the chroma are digital at the source? I'm guessing it would be best, if possible, to digitize (or deal with) each of the four (if I've got the number right) signals individually. I think the challenge (at least one of them, anyway) will be to digitize these signals as accurately as possible, especially given the wide range of colours available on the Atari consoles.

Best of luck in your project!
5-11under

[Longhorn Engineer]

5-11under, on Mon Mar 29, 2010 10:18 AM, said:

This is the way of the future, I believe, especially if you consider digital outputs such as DVI.

First of all, I must say that I'm not too clear on how the 5200 derives colour. If it's similar to the way the 2600 does, then I'm still not too clear on how the three(?) chroma outputs work together - are they all analog, or is just the luma that is analog, while the chroma are digital at the source? I'm guessing it would be best, if possible, to digitize (or deal with) each of the four (if I've got the number right) signals individually. I think the challenge (at least one of them, anyway) will be to digitize these signals as accurately as possible, especially given the wide range of colours available on the Atari consoles.

Best of luck in your project!
5-11under

If its anything like the 2600 and 7800 then it has a 4bit luma signal and a already analog chroma signal that is just 1 signal. I think a 8bit ADC should be enough but I can always use a 10bit it is needed. Chroma comes out as a single signal out of the GTIA. I will probably just use 10 bit. A 8bit would be easier to program and it will give 256 colors (ideally) and as I understand the GTIA can produce 256 different colors. However I think that is cutting it a bit close.

Luma and sync will be able to be connected to the MC without and needed parts as they are digital already. I have been looking at datasheets for ADC video ICs and Ti makes a few that could possibly work (for around $6). The Propeller chip is about $8. Would need a couple caps and resistors so its looking at to be roughly the same price point as the current 2600 and 7800 mods.

This mod should work on Atari 400/800 as I think they use similar setups (digital luma, analog chroma).

The Propeller looks like it can even output digital RGB if you really wanted it to so it can be easily converted to what ever you wanted (HDMI?).

Now this signal will not look better then S-video will but even S-video is beginning to be phased out of HDTVs.

But yes the process that is the most critical is the ADC step for the color. That has to be on target.

[candle]

there is one way that is with us for some time



atari 5200 with vbxe board inside

[Longhorn Engineer]

candle, on Sun Apr 11, 2010 3:53 AM, said:

there is one way that is with us for some time



atari 5200 with vbxe board inside

Thats not exactly what I had in mind candle but thanks.

[sermajic]

candle, on Sun Apr 11, 2010 3:53 AM, said:

there is one way that is with us for some time



atari 5200 with vbxe board inside

did this

http://www.atarihq.c...0faq/04_13.html

tried on 3 5200, no chroma on either , just clean black and white video
tried changing


RCA jack
2k 1uF __
Chroma ---/\/\/---|(-----------------------------------O__ CHROMA
| OUTPUT
GND \/



the 2k with 500 ohms as read in other site, no luck
also tried adjusting the pot for colour

please help!

[thegamezmaster]

wood_jl, on Mon Mar 29, 2010 10:12 AM, said:

Well, if you could make it also work in the Atari 400, that would be cool. The 400 is the bastard child that nobody cares about. As the fledgling low-boy of the line, I think it's really cool to have one with 48k and WOULD BE cool to have a monitor port - or maybe just S-video and composite/sound jacks.

From ANTIC magazine, April 1983 "New Products:"

Quote

XTRAVIDEO 1
(video monitor output)
HARDSEL
P.O. Box 565
Metuchen, NJ 08840
(800) 835-5465
$39.95

This is a plug-in video monitor output module for the ATARI 400. No soldering is required. It uses a standard RCA phono plug and is compatible with most monitors, including the BMC 12.

As I doubt this is going to happen for the lowly bastard 400, anybody know where to get one of these?

The Atari 400 was my first computer and still have one and love it and have many fond memories from back in the day. I'll never get rid of it or quit using it.