Hi Unebonnevie,
welcome!
![Smile :)](./images/smilies/icon_e_smile.gif)
unebonnevie wrote:Hi,
What an incredible project Kiwi is! I happen to find it when I was googling about the Yamaha V9958, which I bought a couple pieces from eBay last night. Btw, the I got five pieces of CXA2075M for $10 (USD) shipping included. That was awesome! I am looking to do a VERY simple project to start learning about the V9958 and the V9990. I am planning use the ATMEGA1284 micro-controller as my "CPU" and hook to the V9958. Write some code and see if there is video on the TV.
Great, another homebrewing project.
![Smile :)](./images/smilies/icon_e_smile.gif)
I have some V9958 as well. I bought them before I knew about the V9990. I don't know the ATmega1284 but as long as it is fast enough to serve an 8 bit databus (the V9958 bus demandings) it should be possible. Recently I did a search for Kiwi's rare parts. There is a posting here about that: "Part suppliers". I found one distributor with better prices I have paid.
unebonnevie wrote:1) I HAVE to connect DRAM to the IC to use as VRAM? Or do I have to use special VRAM chips, like the one that Kiwi does? I thought the V9958, for example, had a 128KB VRAM built-in?
I never did anything with the V9958. I guess it uses normal DRAM. The V9990 uses dual-ported VRAM. For the V9958 it might be possible to do a hack for SRAM. There is a
hack for the ZX Spectrum (which uses a TMS9918) which might help.
No there is no built-in RAM. You don't need to take care about timing and refresh but you should take care about a propper power supply for the DRAMs.
unebonnevie wrote:2) Is there a graphic library for the V9990?
Yes, there is Team Bomba's
GFX9k Library. It is written in Z80 assembly for an MSX computer with GFX9k card.
unebonnevie wrote:3) Are the crystal speed for the V9990 and the RGB encoder IC independent of the CPU's speed? I think these crystals are for NTSC generation? In other words, if I used my ATMEGA2184 at 20Mhz, it really shouldn't matter with the V9990 and RGB encoder's crystal speeds?
Correct. This is what I did. But you should take a look at the VDPs datasheet. As long as you comply with it's CPU bus interface timing it should be ok.
Simon