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The F18a DIY alternative with HDMI :)


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I don't know about the space. How much room over the TMS9918 on there ? You can reduce the height of the board by using machined female pins on the FGPA board and machined male pins on the board I think this will make it smaller. Then the TMS you connect direct the female machined pins from the board. 

 

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@Duewester I was looking into pictures of the TI 99/4a I think the board will hit the case. I need to make a new board with the TMS on top. That would work. I can make a second version and then I will post on the github. I made it for the NABU PC and there is plenty of space. I think it is similar to a CX5MU, my board probably won't fit there.

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34 minutes ago, marauder666 said:

Would this also work on machines which use the TMS9928A(60Hz) or TMS9929A (50Hz) which output something close to component video.  The F18A does work when installed instead of these VDPs.

The code in this solution is the F18A code, and software-wise the TMS9928A and the TMS9929A are identical.  The difference is in clock frequency and output signal.  So to answer your question:  Yes, this board can be used in a TI-99/4A if you get it to fit.  The clearance above the TMS99x8A is much lower than in the NABU PC, however, so the full stack of boards will probably not fit.  Without the RF shield, the second version posted by @retrocanada76 might work, but I'd rather use SMD components to make the stack even smaller - The buffers will fit under the DIL-40 footprint no problem.  It will still be a bit fiddly to get the HDMI cable inside.  Is the VGA output even all that useful if there is HDMI?

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I'd use 74LCX16245 as buffer chips like on the original F18A - They're easy to find and the TSSOP-48 footprint fits into the DIL-40 footprint.  I'd also make the config jumpers into solder jumpers on the PCB underside rather real jumpers as the configuration of the board is typically not changed after it has been installed once.  Let me know if you don't want to KiCAD this and I'll give it a shot.

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53 minutes ago, Hans23 said:

I'd use 74LCX16245 as buffer chips like on the original F18A - They're easy to find and the TSSOP-48 footprint fits into the DIL-40 footprint.  I'd also make the config jumpers into solder jumpers on the PCB underside rather real jumpers as the configuration of the board is typically not changed after it has been installed once.  Let me know if you don't want to KiCAD this and I'll give it a shot.

but then you need what an AND port for the CSR CSW -> OE line ? On TTH an AND port would be large as another LVC245 i just added a read and a write LVC245. If you wan't to make your SMD design go ahead it would be interesting to see. I was thinking in using 3x TSOP-2. For the VGA connector, maybe use the same as the MK1 ?

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