1 Jan
2013
1 Jan
'13
9:36 a.m.
@Mouse: it seems that the Console Code in the rom is
at 2004685a and
upward. The only two occurences of the SCN2681 Register Adresses
[...] are in that region, [...]
20046855: movp $10,$4,$3c
20046859: halt
2004685a: subl2 $24,sp
2004685d: movl $1,r5
20046860: moval 04(ap),r4
20046864: movl (r4),r1
20046867: bisb2 $8,1003(r1)
[...]
Well, the first two lines above are nonsense - movp cannot take
literal/immediate data for all three arguments. This is almost
certainly due to 20046855 being midway through some other instruction;
looking at it myself, I see that segment as being
2004684e: movl $5,1030(r6)
20046853: clrq 1034(r6)
20046857: ret
20046858: movzwl $0,5e24(r2)
2004685d: movl $1,r5
20046860: moval 04(ap),r4
20046864: movl (r4),r1
which is nonsensical enough (movzwl $0 rather than clrl or even
movzbl $0?) to suggest to me that 20046858 is an entry mask, and indeed
disassembling it that way gives
2004684e: movl $5,1030(r6)
20046853: clrq 1034(r6)
20046857: ret
20046858: entry mask: r5 r4 r3 r2
2004685a: subl2 $24,sp
2004685d: movl $1,r5
20046860: moval 04(ap),r4
20046864: movl (r4),r1
which makes a whole lot more sense.
Are you able to find somthing like putchar() and
getchar() there so
that I can call those routines from netbsd's bootloader?
Haven't found them yet, but I haven't looked very much yet. I'll poke
around and, if I manage to find anything, will report back.
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