[Linux-parport] parport_pc disables Hercules mode of mdacon on one
keesan at iamjlamb.com
Wed Jul 21 21:48:29 EDT 2004
I have three computers set up with both VGA and Hercules cards, to display
VC 1 and 2 on the TTL and 3 and 4 on the VGA monitor.
insmod mdacon mda_first_vc=1 mda_last_vc=2
On two of the computers, no matter whether I boot with loadlin from the
Hercules or VGA mode, I end up with two terminals working in each mode.
On the third computer, a 1997 Pentium I with AMI BIOS and a generic
Hercules card (I can check the chip if that helps):
1. Boot from Hercules mode - I get all four terminals displaying in
Hercules mode on the TTL (but I think the last two don't display properly
and get sort of scrambled).
2. Boot from VGA mode - terminals 3 and 4 now display properly in VGA
mode but terminals 1 and 2 have the text smeared out across the line
I have parport and parport_pc in rc.S to insmod when I boot on all three
I was able to get the third computer to work by NOT insmod'ing the
parport_pc module. Load all the modules manually and mdacon works
properly with parport_pc, but then I load parport_pc and the Hercules mode
goes bad again. It does not help to load mdacon before rather than after
parport_pc, or to rmmod parport_pc after the problem occurs.
The fix is either not to use mdacon at all, or to insmod parport_pc
manually only when needed for printing, after first switching to a VGA
terminal. Then I need to reboot (into DOS and then again into linux) to
use both monitors. I don't often print in linux.
Slackware 7.1, 2.2.16 kernel (specially compiled with minimal drivers for
Basiclinux 2). I have not tried a different Hercules card in there, or a
different kernel (bare.i, for instance, which I think has parport_pc built
My theory is that mdacon and parport_pc are using the same RAM on that
computer, if that is possible. Another computer will not work at all with
Hercules cards due to RAM conflicts of some sort, I think.
Is there some way to specify where in RAM to load a module?
Would it help anyone if I were to try a different Hercules card or a
different kernel and report back?
DOS works fine as far as switching between monitors with the mode command.
I have the workaround, but am posting because I could not find any related
cases and hope to help someone else (not that a lot of people are
currently using TTL monitors for linux). I presume if I knew enough I
could rewrite mdacon.c or parport_pc.c and compile them myself.
I don't know of a way to use my printers without parport_pc.
More information about the Linux-parport