> It's my understanding that saying that the bus speed is 33 MHz means that
> data is transferred every 30.3+ nSec. The original PCI bus is a 16-bit bus
> so 33-MHz is the (16-bit) word speed and the byte rate is 66 MB/Sec. Newer
> PCI bus architecture expands to either 66 MHz or 32-bit words or both.
I should have said 33 MHz is the PCI clock speed. Data can be
transferred on every clock, but I've only been able to do it with the DMA
functions built into various PCI cards. I recently had a long search for
a simple parallel interface board which had dma onboard and they claim it
can do 80mb/sec.
I think the PCI bus has always 32 bits wide since day-one. The original
clock speed was 33mhz, and there are now motherboards with 66 Mhz clocks.
There are also families of 3-volt and 5-volt pci cards. Perhaps the 66mhz
stuff is all at 3.3 volts.
It would be real nice to have a single IO MOV instruction which was as
fast as DMA.
-W Wright
-- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
--
For more information on Real-Time Linux see:
http://www.rtlinux.org/
