> As usual I am still quite confused > If the Mesa hardware will do the critical work, step generation, why > does it matter so much about the motherboard > > Richard
I believe that without the full EPP in effect, the port has some pins that are write only, and some that read only. IIRC the readable pins in the other modes only add up to 5 (a normal printers status bits), but I'd expect the mesa boards need a full 8 bits going both ways, and only the EPP mode can do that. Peter W. can clarify that if I'm full of it since IIRC those boards are his. :) Better it comes straight from the person who knows for sure. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> The eyes of taxes are upon you. Yes when EPP mode is used for communicating with smart peripherals (like Mesa or Pico) it is used as a bidirectional 8 bit data/address bus. Other modes can do this (the so called PS2 mode can) but EPP mode has built in strobe generation and handshaking so is much faster for data transfer than PS2 mode (and much simpler than ECP mode). To add to the confusion sometimes EPP mode is suggested for software step setups, The reason being that some parallel ports change the I/O mode of some pins from open drain with a pullup to push-pull when in EPP mode VS SPP or PS2 mode. If the pin needs to source current to drive an OPTO this may be neccesary. ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
