Jon Elson wrote: > John Thornton wrote: >> What is DMA? >> > Direct Memory Access. The IEEE-1284 port under ECP mode can transfer > huge blocks > of data to/from system memory without CPU intervention. This is great > for parallel port > Ethernet (thankfully now replaced with USB) and par port page scanners, > and printers, > etc. It is much less likely to be useful for servo motor control as the > blocks being transferred > are going to be quite short.
I agree there would not be much to be gained by running the parports in ECP mode. Mesa is planning to use DMA not for the parport boards, but for the PCI and PCI-Express boards. PCI I/O latency is dominated by bus setup and negotiation, this is especially bad when several busses are chained, as they are with the 3x20. DMA should provide a dramatic speedup in this situation. -- Sebastian Kuzminsky ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
