Video output from the HEC!
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- čas přidán 22. 11. 2022
- As a response to the recent progress of the Z80 Retro Board project, I decided to first do something with the TMS9918. Here is the result.
Someone in the comment section of my last video suggested me showing the bottom side of the board, I planned to do it in this video, but forgot it entirely... - Věda a technologie
Well done! Keep going 😉. DRAM s are power hogs...hence the decoupling capacitors being required to prevent relatively large glitches in the power lines.
Excellent work, I am very proud of you.
hello Andy,
It's a nice project that you have. Juste one thing about noise, IMOH I would put a 100nF close to every single chip on the board to avoid noise related problem as it is stated in every chip datasheet.
Keep the good work, can't wait to see you launching an MSX game on your board!
Looks great, nice clean image and sharp font render.
Not sure if it was intentional, but I liked how the text was typed out character by character. Very nostalgic, like old teletype or terminal emulators.
It is kind of intentional. The original goal is to type each character during vblank, so I poll the VDP for that. I'm sure I can do 2 or even more characters at a time, but didn't implement it for simplicity, plus coolness!
Congrats of getting it to work ! Must be amazing to see the hardware come to life like that 💪 Looking forward to the details of Monika ..
PS: Which font did you use, is it the MSX font by any chance ?
Yes it is. Because it fits into 6-by-8 pixels. (So I can use it in text mode)
Maybe you want to explore the video input mixing feature of the chip.
I do. But I am 90% sure that it will be a mess. Core problem? the phase of the color subcarrier of the input composite signal must be absolutely in sync with the signal from the TMS9918, otherwise the color will be messed up. I may be able to get around this by hooking up two TMS9918s and feed them exactly the same clock and reset signal, but overlaying TMS9918 image on the output of something like a VHS player is going to be almost impossible.
Are you still implementing your design for memory protection? I think it'd be interesting to look at ways you can make use of it within an OS light enough to run on the Z80 in general
Yes and no. This board is capable of all the things I talked about in that video. But only a small portion of it has been tested working. Therefore I'm currently running it under some sort of 'real mode' and the CPU has access to everything.
@@andyhu9542 Maybe just have a switch that enables the memory protection, and some AND gates so it loads a different ROM with the memory protected OS.