1 Jan
2013
1 Jan
'13
10:07 a.m.
Mouse wrote:
Cool. I don't even know what the heck an entry mask is.
Sorry, never done assembler on such an "big" machine.
There are two occurences of "0c 00 10 20" in the code, at 200468b2 and
20046932. 0x201000C is the Address of the SCN2681 Transmit Buffer/Receiver
Holding register so I think the routines should be there. The Address ofi
the Channel A Status Register 20100004 is also appearing in this area
(200468a3, 20046923, later at 20046c82, 20046cca and 2004c43c).
Regards,
Holm
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@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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