9978 as coprocessor as the 9990 is to. just use need nice hardware to combine video output. bad my 8280 does not have rhb in and out
I'm lucky to have access to Video9000, but I guess it would not hurt if someone would redesign it with this millennium technology and make it available for wider audience. Out of all implementations I guess it is most close to what V9978 could have been.
You are right.
We have plans to make a full version with superimpose of KrakenGraph but have been delayed due to design and production of our Wozblaster Enhanced.
Now it's time to finish KrakenGraph Lite and then, the full version.
If you make a full version, can you put the Kanjis on a flashrom (or Rom in a slot) for the possibility of replacing them with something else? (eg Hangul, etc)
I too think both V9958 and V9990 combined on a single chip would’ve been what they were going for. The V9990 is clearly not designed to be V9958-compatible (just similar in spirit), so the logical backwards compatible solution is to include the V9958 verbatim and overlay them through the superimpose mechanism. This approach then allowed Yamaha to design the new VDP capabilities unrestrained by legacy considerations (unlike the V9938 which was encumbered by the TMS9918 design legacy).
what we need is someone liking to create an equivalent board in VHDL, sort of a re-engineered V99x8 core with V9990 capabilities.
however i do not know how it is possible to squeze the two vdp's cores in a single FPGA.
if succeded one could replace the internal vdp with this board, but probably it is not easy (due to pinout) as is with F18A that can work as pin compatible with TMS. V9990+V99x8 have a lot of pins.....
I doubt we would have anything different from V9990 as we know. maybe only the i/o ports layout: its structure would be backwards compatible with V9958 and it would implement Text1,Text2, Graphic1, Graphic2 and multicolor graphic modes along the sprite engine (it already implements every bitmapped mode contained in V9938 and V9958 with slight differences in memory mapping and sprite support)
Actually, I wouldn't be surprised at all if yamaha planned to implement backward compatibility using an external PLD/ASIC which translated TMS/V99x8 instructions into V9978(V9990) instructions.
V9990 has been developed based on V9978 specification, but it was not intended to use in MSX.
The original plan of VDP upgrading at the time of MSX2 standard released was implementing multiple VDPs.
Color Bus, included in V99x8 was prepared for that functionality.
IMHO, VDP improvement should be overlaid on V99x8 via its color bus. And if it is that way, any functions will be allowed.
In fact, external palette extension using V99C37 has been released for FS-5000/5500.
We can connect any video device through the color bus, like SMS VDP, Genesis VDP, and V9990 of course.
The important thing is that V99x8 itself needs to be installed for V99x8 compatibility.
