Author: stimpy (host62-7-162-29.webport.bt.net)
Date: 01-29-2002 22:58
>According to Michael Ruge's Chips'n Chips >docu, no part of the ST accesses RAM at 16 >MHz.
Indeed, but the MCU does run at 16MHz, I believe to allow timing for allowing the accesses from Shifter and CPU/DMA/Blitter. The Shifter does a complete line at one time (When DE is high) and the MCU pumps data out to Shifter.
>About 133 MHz SDRAMs:
>Yes, they are cheap and you can run the >DIMMs in 66.5 MHz, too, as far as i know
>(Johan can tell better). But there's >basically no sense in running the RAM >faster than the CPU.
Well for good compatibility I think using system RAM for the video is best. Therefore, running RAM at 133Mhz will allow good bandwidth. Some SDRAM does not work slower! Just shove configurable waitstaes in for CPU, it leaves options open, some sort of configure tool would be written, like the setup in PC BIOS. You might as well have the DMA running at full speed of bus as well.
|
