Hopefully other people find this as interesting as I do...
The problem with component output from the TI-99/4a, is that the 9918 chip in the US versions of this computer only outputs composite.
Until recently, it's been pretty much said that component output isn't possible because of the 9918.
Turns out this can be swapped with the 9928 chips, like in the Coleco's. In fact the UK versions of the TI-99/4a actually used the 9928.
But a Coleco doesn't have to be torn apart, as this chip can be bought for like $10.00 at http://www.arcadechips.com/product_info ... ucts_id=85
The 9928 outputs R-Y, B-Y, and Y.
A Djpubba at atariage.com has been actually experimenting with this, but is mostly focusing on RGB.
The big thing to note is that it has been actually shown now that the component output from the 9928 *will* need additional circuitry to work with the component inputs of a television.
The thread on Atariage where this has been discussed is:
http://www.atariage.com/forums/index.ph ... 5191&st=50
It started out as a thread about the state of TI-99/4a web sites and quickly became about getting composite output from the TI!
Djpubba’s focus is RGB output, rather than component or S-video, but did some really cool experiments with straight component output from the 9928 on post # 54, and then trying the ColecoVision video mod from 8bitdomain on post # 59.
It turns out, neither worked right (colors off, oversaturated)
On post #60 and #62 he tried it with 100k pots and then also pull-down resistors and got a great picture.
At this point, he refocuses on RGB, so if anyone tries to create a circuit for this to get proper component output, or possibly S-video they will be on their own at this point…….
For those interested in RGB, he used the Vidiot board in a Baby Pac-man which uses a 9928 and converts its output to standard RGB + Sync. It seems to have worked very well!
Schematics for the Vidiot are at
http://arcadecollecting.xmission.com/rgvac/babypac.pdf
This all started when I decided I wanted to pay someone to get component or S-video output for the TI-99/4A and found the thread on Atariage where a solution was being discussed.
So, I'm trying to generate interest in this really cool project wherever I can, just because it's so exciting!
And perhaps if I'm lucky once someone is successful doing this and posts what they did, I'm hoping to be able to pay someone skilled to do this mod for me...
(I have no electronics experience so I can't do it myself)
Anyway, just thought I’d see what people here think about this modification...
Ti-99/4a-Getting component output
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Life of Brian
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