Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Make Ys available on the RGB connector #39

Open
sdsnatcher opened this issue Jul 3, 2022 · 3 comments
Open

Make Ys available on the RGB connector #39

sdsnatcher opened this issue Jul 3, 2022 · 3 comments
Labels
enhancement New feature or request

Comments

@sdsnatcher
Copy link

sdsnatcher commented Jul 3, 2022

Please add the Ys signal to the RGB connector. The pin-5 of the DIN-8 MSX RGB connector was meant to be the Ys signal from the VDP.

To save some pennies on a transistor, many MSX models came with just a resistor divider connected to that pin.

But for those on the SCART world, it's very useful to have a funcional Ys pin, since the TV can superimpose the MSX image over other sources.

I attached here a screenshot of how it was implemented on the Philips NMS-8245.

Philips-NMS-8245_Ys_pin

@sdsnatcher
Copy link
Author

There are a lot of free inverters on the current Omega schematic, and any of them could also be used to implement the Ys signal too:

Ys_pin_on_Omega_proposal

@skiselev
Copy link
Owner

skiselev commented Jul 3, 2022

Thanks for the suggestion! I'll add it to the next revision.

@skiselev skiselev added the enhancement New feature or request label Jun 28, 2023
@Leshak-pcb
Copy link

There are a lot of free inverters on the current Omega schematic, and any of them could also be used to implement the Ys signal too:

Ys_pin_on_Omega_proposal

Since Ys is terminated with 75 Omh resistance this is probably too much for 74HCT04. Increasing series to 150 Omh results in 18.7 mA current - pretty high, but acceptable for 74HCT.
74ACT04 can source up to 24 mA, but is it suitable for a clock generator?

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
enhancement New feature or request
Projects
None yet
Development

No branches or pull requests

3 participants