On Wednesday 21 Aug 2002 18:14, Z F wrote:
> Do you think that the problem with ECP printing is related to the
> software or it is the printer which does not understand ECP protocol?
I'm not sure. It could be either. Or, if the printer is 'daisy-chained' off
the SuperDisk drive, it could be to do with the extra connectors and
cable-length affecting signal-integrity in high-speed ECP mode.
I seem to remember that I always found printing through my PP drive somewhat
unreliable, both under Windows and Linux. I eventually bought a
USB-to-Parallel cable for the printer which solved the problem nicely.
>> ... the SuperDisk almost certainly uses EPP mode, and will
>> work substantially slower if ECP mode (or ECP+EPP mode) is selected.
> I must say that while SuperDisk works, it consumes huge amounts of CPU
> resources and it is practically impossible to do anything while the
> disk is in use. System load goes to 2.00 on my Pen4 1.7GHz even with
> nice=20 parameter.
I think that's much the same for any parallel-port disk device. My SyQuest
drive does the same if I do large uninterrupted reads/writes. Recent kernels
seem to be much better in that respect, though. I'm using 2.4.19 now and,
although the system becomes a little bit choppy at times, I can still use KDE
successfully while the drive is being accessed. Kernel preemption may also
For reference, my Panasonic IDE LS-120 SuperDisk drive (double-speed, 1440rpm)
gives me about 825kB/s for the first 8MB of an LS-120 disk. You should be
able to cram about 1MB/s through the port in EPP mode (according to
benchmarks I ran on the SyQuest drive under Windows some years ago) but the
Linux driver seems to struggle to reach 350kB/s. Or maybe it's just the drive
getting old :-)
>> You should be able to see something in your dmesg output from the
>> protocol driver that tells you what mode it's currently using...
>> Example from my EPAT-based SyQuest drive
> I guess you are talking about "mode 5(EPP-32)" in your example which
> would change when switching between EPP and ECP port modes?
Yes, sorry, I forgot to point out that bit. It would drop back to "mode 0
(4-bit)" or something if the port was in ECP or ECP+EPP mode. (It's a while
since I last tried it.) And the drive would come screeching to a halt, or
very nearly - IIRC, I used to get about 50kB/s when I attached the drive to
my old non-EPP-capable 486 PC.
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