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repetto74

New to TI99/4A video mod

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Hi to all,

 

I am an happy owner of a PAL TI99/4A since today (I am located in Europe) :-). The machine comes with the RF antenna cable with the big RF PAL modulator and the 6 pin DIN video socket output. I can test this with an old CRT TV I still have but I would like to know what are the best video modding options available to increase video output? Composite, S-video? Any tutorial?

 

Besides that are there also hardware mods available to increase total memory or to improve the machine performance in general?

 

Sorry I am really a noob with the TI99/4A so trying to sum up what is possible to do. Consider that I do have soldering and basic electronic skills + all tools required for the job :-)

 

Many thanks,

Rick

:grin:

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Is that the scart adapter? If so you can use that with hdmi with a cheap box.. if not, the best option is the f18a which is detailed in the "new to the group" faq pinned to the top of the forum

 

Greg

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Hi Arcadeshopper,

 

Nope the RF modulator is not the one with the SCART (PERITEL) output for the french market. I got this from an italian e-bayer and the modulator has been manufactured in Italy also but will need a TV antenna input.

 

To Sinphaltimus : thanks for the greetings and will read closely the thread :-)

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Hi to all,

 

I am an happy owner of a PAL TI99/4A since today (I am located in Europe) :-). The machine comes with the RF antenna cable with the big RF PAL modulator and the 6 pin DIN video socket output. I can test this with an old CRT TV I still have but I would like to know what are the best video modding options available to increase video output? Composite, S-video? Any tutorial?

 

Besides that are there also hardware mods available to increase total memory or to improve the machine performance in general?

 

Sorry I am really a noob with the TI99/4A so trying to sum up what is possible to do. Consider that I do have soldering and basic electronic skills + all tools required for the job :-)

 

Many thanks,

Rick

:grin:

 

Hello Rick :)

 

on the Italian User Club website you can read some guides/tutorials for a mod to the PHA 2036/2030

 

Check out at this link if it can help ;)

http://www.ti99iuc.it/web/index.php?pageid=119&pagina=mod_proj1&sezione=4&data=Mod_and_Tuneed

Edited by ti99iuc

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Best video mod is to fit an F18A to give a VGA output as Greg said above. But if you wanted to stay 'old school' and you have the version of the PAL modulator in a metal case (as opposed to the one in the plastic case), it is possible to get a composite video feed out of it. The attached scan (in German) shows you the basics but you will probably have to do a bit of fiddling to find the right connection points and so on. Instead of fitting a DIN connector as shown, I fed a coaxial cable direct into the case and connected it direct to output of the little video amplifier circuit.

post-31406-0-42789400-1505168165_thumb.jpg

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Hi Stuart

 

Thanks a lot for the schematic. Actually I have various working 8bit machines I would like to output to the same HD TV and with the best option possible. Wherever an S-video mod was possible it was done (Atari XL, VIC-20), composite is the second option when S-video is not possible (ZX Spectrum). The C64 and the Spectrum 128k are respectively S-video and RGB native.

I am using a video upscaler AV/S-Video to HDMI which gives a really nice conversion to the HDMI TV. A composite mod to the TI99/4A will be a very good result then :-)

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I have a modified such modulator, where I get separate sound and video out. I use coaxial connectors for both, one BNC and one of a different type, to easily tell them apart.

 

My console has 64 K 16-bit wide RAM internally, which is another modification which adds both memory and also speed. All external memory (in the expansion box) is otherwise 8-bit wide.

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My old LCD-TV (LG 42LF65) took the TI signals on YPbPr input - best possible quality without any modulator!

The RGB circuit in "Chicago TImes" (ca. 11/1986) is quite easy, only a handful of transistors and passives. That is my favourite, if you have a RGB-capable Scart input.

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Yes the TV can handle RGB as I connected a Spectrum 128k +2 Grey model which comes with a RGB video output through a SCART cable. Any tutorial on how to do this also?

:-D

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Hi Apersson850

 

Any link for a tutorial explaining how to mod the TI99/4A to 64K ?

There must be some for a similar modification. Probably on WHTech. But not exactly for my modification, as it's my own design.

Normally the similar modification installs 32 K RAM inside the console. But to get it 16 bit wide, you but two 32 K chips in there. I though that was a tad stupid, to leave 32 K unused, so I came up with an additional circuit design, which allows you to page in the other 32 K too, 8 K at a time, so that you can get 64 K contiguous RAM in the machine. Thus you can overwrite ROM and change the operating system too, if you like. My design also allows disabling the internal 32 K normal memory expansion. If you want to. If you do, the CPU will instead see a 32 K RAM expansion in the expansion box, i.e. the normal memory expansion.

So my design allows more than just a memory expansion.

  • Fast 32 K RAM expansion internally
  • Another 4 * 8 K RAM can be enabled, overlapping all other memory banks in the console
  • The 32 K internal expansion can be disabled, to allow access to 32 K RAM in the expansion box

The paging is done with CRU bits. The design is done so that it starts with the fast internal 32 K RAM expansion enabled, and the rest disabled. Thus, after a reset, the machine behaves like it had a normal 32 K RAM expansion, just faster.

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Hi Apersson850,

 

Ok now I understand what you mean. Well I would say that considering the fact that the CPU can address 32k of ram maximum I would say that this will be enough for me.

I am just a newbie for what concerns TI99/4A and have a lot of work to do in order to use the machine correctly. Actually I need to build a cassette tape cable to use with the cassette recorder. Then I can consider modding the total ram to 32k (found this tutorial https://www.harmlesslion.com/text/TI%2032k%20Mod.pdf)and then maybe later on I may consider a nanoPEB if this piece of electronic is still available for sale :-)

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