On  5 Jul 98 at 5:40, ghelm wrote:

> In the BIOS setup of my TX motherboard I have three (3) printer port
> options.  Can someone please explain the differences between "ECP",
> "EPP", "SPP" port settings.

SPP:
  Standard Printer Port
    Might include birdirectional operation if the port hardware
supports it.  often has an IRQ reserved, but never uses it.

EPP:
  Enhanced Parallel Port
    One approach to making the parallel port more useful for other
sorts of external devices.  Uses an IRQ.

ECP:
  Enhanced Communications Port
    Another, more extensive, approach to making the parallel port
useful for external devices.  Uses an IRQ and a DMA channel.

  Some BIOSes offer a fourth "EPP/ECP" selection, which tries to be
compatible with use as either type.

  The parallel port was designed to send data to a (slow) printer,
and receive a few status signals (e.g. Not Ready, Out of Paper) back.
Although some early clones saved a few pennies by not doing so,
people discovered that IBM's original Monochrome Display Adapter
could receive as well as send data.  Ever since then there has been a
small market for external devices which interface through this port.
[Parallel means that it can move bytes in the time it takes a serial
port to move BITS, theoretically.]  Hard Drives, CD-ROM drives,
networking connections, scanners, Zip drives ....
  EPP and ECP are the results of two separate standards efforts to
enhance the parallel port in order to improve the performance of such
a connection.

  Rules of thumb:  Most printers are happy with SPP, unless they
offer advanced features or high throughput.  Most mass storage
devices want ECP if at all possible, and will be slowed considerably
by anything less.

David G