> On 11/3/21 6:29 PM, Claudio Sánchez wrote: >> Ideas: >> >> - Create a secondary display card with a VIC-II that would use >> its own memory. > > Use the VDC from the C128 as a second video chip, but that one can run on its own 16 MHz clock... Maybe you could double the dot clock and use that instead? > > Gerrit Yes, I thought about a secondary video chip, but the way it should be handled by the CPU wouldn't be the same as the VIC-II is handled... More than anything else because the VIC-II handles the CPU!!! I would like to know how the BA line works in the C64, as seen from the cartridge slot, regarding the VIC-II. I mean... THE BA and /DMA lines are used to "unlink" the CPU from the bus so an external device can directly write to the internal memory, but... how do this relate to the VIC-II? The VIC-II cannot be unlinked from the bus AFAIK, so... (light bulb turns on in my head) maybe *that* is the reason of the presence of the DOT clock in the cartridge slot. To make whatever is attached to the expansion bus be able to be in sync with the VIC-II, that cannot be stopped. I think that by using DOT clock, the external device would replace the CPU in the turn it has to access the internal RAM. ADDENDUM: Corrections and/or enhancements are encouraged.Received on 2021-11-05 21:00:02
Archive generated by hypermail 2.3.0.