Re: problem reading VGA text fonts

Martin Ostermann (ost@comnets.rwth-aachen.de)
19 Nov 1996 13:24:39 +0100

koenig@tat.physik.uni-tuebingen.de (Harald Koenig) writes:

>
> what's different between AXP and x86 ?

Hm, just came back to my mind ... When I did my first Jensen patch, I
used BusToMem() to replace slowbcopy. That didn't work. The difference
basically was, that BusToMem() reads a word at a time, not bytes.

If you use DENSE memory, the AXP reads a quadword at a time. The
SlowBcopy routine does this. Maybe this isn't OK on some cards?
OTOH, the outb() in there should make sure that that's done for each
byte to read.

Anyway, there's probably a reason that this routine was called
slowb(yte)copy in the first place.

> what should be tested/checked next ?

Try to access the font space via SPARSE memory, a byte at a time. You
can use the Jensen Patch with TEST_JENSEN defined, but make sure you
fix the tests in SlowBcopy.c, which weren't made depended on the
define.

Martin

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