PCI throughput on older PC31

mrippa · Joined: 09 May 2008 Posts: 1

Hi -

I was trying to calculate the theoretical throughput from a DOS host to the PC31 target through dual port memory. MY PC31 has a TMS320C31 with a 60MHz clock. The board is configured for 32-bit wide dual port memory.

So running on a 33 MHz pci bus, I should get 133 MB/s. Is there anything on the PC31 side that limits this? According the the hardware manual, I'm "zero wait-stated" with the 32-bit wide DPR configuration.

Thanks,
-Matt

gmiller · Joined: 07 Mar 2006 Posts: 105 Location: Simi Valley, CA.

The ISA is not going to give the maximum throughput in a windows computer 16Mhz. This is the buss speed for burst mode. In reality you can only get about 1/2 this speed maximum to start with. Since there is burst more and request time this leads to slower over all accesses. On the ISA with the buss requests and latency of windows I would expect maybe a max of 8Mhz for a throughput rate. Each computer will vary from there. This rate will be downgraded from there depending on what the DSP has to do. If there is high interrupts and other calculations this will be much lower. PCI is much faster with a 33Mhz or 66Mhz clock.

Respectfully Gary