Author: redspctr (dnvrdslgw13poola167.dnvr.uswest.net)
Date: 08-07-2002 02:50
I noticed on the Falcon schematics that the DSP has an X/Y pin that is seems to be used to select which "bank" of memory to use. Or at least that's what I thought it was. Does another pin select external program memory?
Also, the schematics only show address lines 0-14 being used to access the memory. Does this mean that 15 is not connected? Is it available?
I did a search for DSP memory expansions. It seems that there was a daughter board made for the NEXT that boosted the memory to "192K". I take it they meant bytes, not 24bit words.
I read that you swapped your chips out with 15ns SRAMs. Was this difficult. Are they difficult to aquire? Do you know what effect this has on instruction timing? Motorola claims that each external access incures a 1 instruction-cycle penalty. I thought that this was the case with the falcon. But I gather from your comments on your speed increase using ACE, that a 50mhz DSP incures a heavier penalty.
p.s. A bank switching scheme would be really cool on the Falcons DSP, it would allow me to load up the DSP with sample data thereby eliminating the costly send routines! Yeah, 16Megs would be nice for that!