Kirk Wallace wrote: > On Fri, 2011-01-28 at 14:55 -0800, Kirk Wallace wrote: > ... snip > >> I found a card that looks a lot like a Sunix PAR4018 which is known to >> work(?), on Newegg: >> http://www.newegg.com/Product/Product.aspx?Item=N82E16815158040 >> > > Oops, Newegg's picture has "4008T" on the board so it may or may not be > a "4018", but I guess I'll find out. > > I tested years ago with a 4008A chip, and it worked fine! > I also forgot to mention that ECP may not be an option because it uses a > FIFO which has latency which is a bad thing. So really, if EPP is > broken, that only leaves SPP and PS2 modes, or some other user defined > mode which would be unique to the application. > ECP is not an extension of EPP, it is a way to make really fast streaming transfers to a device that works just like a standard parallel port, like a printer. So, if the remote device wants EPP, then ECP is not at all compatible. EPP has both address and data transfers, so you can have an array of registers and write to or read from them in sequence. ECP has no address transfer, so you'd need to adapt some other signal to make the distinction. Also, EPP has the computer always the master, while with ECP, the drvice becomes the master when the computer is reading. It is a totally different scheme. ECP does not really use a FIFO, it does DMA to/from system memory. Also, it isn't clear whether DMA is easily handled under the RTAI environment. If not, then ECP isn't going to work.
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