TRH9000 - The Yamaha V9990 based open-source video card for the MSX

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By crisag

Resident (39)

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10-09-2022, 16:46

I've been busy with boring work stuff but had some time today to move this thing forward and update you all. I just published to github the prototype board I'm using to validate the main circuit and make some tests with different sync separators/rgb encoders. It is based on the work done by Alexey Wierzbowsky and was adapted to have pads for memory chips, V9990, and two different video chips. I'm testing the Sony RGB encoder (CXA2075M) and the TI Auto-Detecting SD/HD/PC Video Sync Separator (LMH1980) to generate the video signal and study options for superimpose.

Testing the circuit, I found a pin assignment problem on the memory chips that is now fixed. Still need to test a few things and planning to do that in the upcoming weeks.

By sdsnatcher73

Prophet (3668)

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11-09-2022, 07:01

Cool, nice progress! Thanks for keeping us updated.

By erikmaas

Expert (69)

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12-09-2022, 14:01

I notice that on the old schematic (TRH9000_Schema_Revision_0.pdf) there is no connection to busdir. This means that on some computers and slot-expanders you are unable to do I/O reads.

By sdsnatcher73

Prophet (3668)

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12-09-2022, 15:15

Good catch erikmaas! Some info on BUSDIR here and here.

By crisag

Resident (39)

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21-09-2022, 07:22

Thank you both for catching the mistake and providing documentation. I'll implement the circuit to derive the BUSSDIR signal and update the project. Here is a picture of the current prototype. Of course, BUSSDIR is missing there. Smile Fixing it asap.

By sdsnatcher73

Prophet (3668)

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21-09-2022, 08:00

Cool!

By gdx

Enlighted (5847)

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21-09-2022, 10:01

if you are going to do a v9990 with an FPGA, why not make an HDMI output?

By sdsnatcher73

Prophet (3668)

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21-09-2022, 11:10

gdx wrote:

if you are going to do a v9990 with an FPGA, why not make an HDMI output?

Who said anything about an FPGA? It’s using a real V9990.

By PingPong

Prophet (3992)

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21-09-2022, 12:54

cool! is it a working prototype ?

By gdx

Enlighted (5847)

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21-09-2022, 14:28

Oops, I confused with another thread.

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