Archived from groups: comp.periphs.printers (
More info?)
In article <8uned05bcvsjbifk6de1rd14tr7p45061m@4ax.com>, Rob
<tele*deletethis*manr@hotmail.com> writes
>Plus you need to have USB 2.0 which you'd find on a newer computer but
>not on an older one. It would make a huge difference. USB 1 would
>definitely be slower than parallel (I believe).
>
That depends on the motherboard and the port configuration.
The actual speeds of the ports are:
standard parallel port: 115kBYTES/s 0.115MBYTES/s)
USB-1: 12Mbits/s 1.5MBYTES/s
ECP/EPP parallel port: 3MBYTES/s
However, in addition to this is the protocol and handshaking overhead.
Data through the parallel port is byte-at-a-time processing, with the
processor needing to poll the port to find out if the last byte has been
acknowledged before it can send the next. This slows the process
considerably and can, depending on the motherboard hardware, heavily tie
the processor up until the entire data stream is sent to the port. USB,
on the other hand is a burst mode bus, where entire streams of data are
sent and acknowledged as a burst. This leaves the processor free to get
the next burst of data or implement something else entirely whilst each
burst is being transmitted. So, even though the peak data rate from an
ECP or EPP parallel port can exceed the data rate over USB-1, there is
usually very little difference in the sustained data rate between them,
and the processor is usually much less loaded by USB than parallel,
which means it gets back to servicing your input quicker.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a ah heck when he's pissed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)