Sorry my question is a little off topic, but, perhaps you know.
In an A2000 system with a 32-bit accelerator and 32-bit fast ram, is there any improvement in the A2091's performance by adding the 2 Megs of 16-bit Fast Ram to the card itself? Faster DMA? More buffer?
In a purely 16-bit A2000 (No 32-bit accel or mem), does the A2091 perform better when populated with those same 2 Megs of Fast versus having all the Fast Ram on a separate ram expansion?
It depends on where the 32 bit Fast RAM is located. If it's in 24 bit address space the A2091 can DMA directly to it but if it's in extended 32 bit address space then the A2091 must either use PIO (or a buffered DMA patch) to perform the transfer. The DMA buffer is either in MEMF_24 or Chip RAM so A2091 Fast RAM is important for extended 32 bit Fast RAM only systems.
The filesystem uses a fixed amount of memory for a buffer specified in the RDB or mountlist at boot time. Additional buffering is used when a buffered DMA patch is installed but not by the filesystem.
Yes, in a purely 16 bit A2000, the A2091 Fast memory is still a little faster than chip memory thus performance is improved.
Can this co-exist with the 14mhz a2091 mod?
A better question is why would it not co-exist?
