In article <19991021163116.17429.rocketmail_at_web604.mail.yahoo.com>, Ethan Dicks <ethan_dicks_at_yahoo.com> wrote:
>
>In my ongoing excavations, I've located an orphan board that I would like to
>return to its nest. It's a diode-strapped boot card, M792-YB. The pattern
>looks like this...
>
>
>- - - - - - - - - - - - - - - -
>- o o o o o - - - - - o - o o o 0
>The question is, What's a one and what's a
>zero? Left-to-right? I don't have an -11
>frontpanel or handbook in front of me; is
>bit 0 the MSB?
Looks like only diode=1, right=MSB produces plausible code.
>Any hints? Worst case, I could translate all permutations of the bits
>into octal and figure out what produces the most legible bitstream,
That's what I did :-) Tiny script using Supnik's emulator.
>The eventual goal is to disassemble the bootstrap, thus revealing what
>device it is for.
0: MOV _at_#177570,R1
4: RESET
6: MOV R1,R0
10: MOV #177400,(R0)
14: CMP R0,#177344
20: BNE 40
22: MOV #4002,-(R0)
26: TST (R0)
30: BPL 26
32: TST -(R0)
34: BPL 4
36: CMP (R0)+,(R0)+
40: MOV #5,-(R0)
44: TSTB (R0)
46: BPL 44
50: TST (R0)
52: BMI 4
54: CLRB (R0)
56: JMP _at_#0
62: WAIT
--
Kevin Schoedel
schoedel_at_kw.igs.net
Received on Thu Oct 21 1999 - 12:19:00 BST