more VXT2000 stuff

Hello.

I have borrowed a VXT2000 model VX20A-AA, and, of course, it is slightly
different than my VX20A-CA.  First of all, it has a memory hole; there
is no region of memory 200000-3fffff. This is unfortunate, because the
boot program is relocated to somewhere in that region.

Changing RELOC=0x39F000 in sys/arch/vax/boot/Makefile.inc to something
else which is actually in an existing memory region, for example
0x3d000, solves that problem.  (Why is the address 0x39f000 the default
value?)

(The -CA loads the MOP image at 0xd000, the -AA at 0x400a00. This should
probably not matter.)

Then there is the problem again with console output.  (Maybe I should
emphasize that I'm not using a _serial_ console.  I'm using keyboard +
monitor as my console.)

Using rom routines, 20040058 is putchar, and 20040044 is a non-blocking
getchar, just as on my VX20A-CA.  With these routines, the boot program
runs, detects ethernet and does all the rarp + nfs stuff.  (Compiling
the kernel seems to work up until the final link. Then it fails. So I
don't know how far it would make it inside the kernel.)

Ragge's putchar/getchar doesn't work on either of the two VXTs I have
tried.  (One possible explanation could be that Ragge is using serial
console. (??))

However, if I change the line

	static volatile int *vxtregs = (int *)0x200A0000;

in .../vax/boot/boot/consio.c to 0x200A0040 instead, I can read data
from the keyboard, but the values returned are keyboard scan codes and
not ASCII values.



Anders