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BSD boot sequences expects csr in R1

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This commit is contained in:
Neil Webber 2025-04-06 08:13:39 -05:00
parent 9b0c1b906f
commit 2e6359f384
1 changed files with 8 additions and 6 deletions
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14
boot.py
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@ -48,15 +48,17 @@ def boot_hp(p, /, *, addr=0o10000, deposit_only=False, switches=0):
# NOTE WELL: THIS ASSUMES THE MACHINE IS IN RESET CONDITION WHICH
# MEANS MANY OF THE DEVICE REGISTERS ARE ASSUMED TO BE ZERO
#
# MOV #176704,R0 -- note how used
# MOV #177000,-(R0) -- word count - read 1K though boot really 512
# MOV #071,-(R0) -- go!
# The BSD boot program expects to find the CSR (176700) in R1. Note
# how cute this little program is in obeying that :)
# MOV #176704,R1 -- note how used
# MOV #177000,-(R1) -- word count - read 1K though boot really 512
# MOV #071,-(R1) -- go!
program_insts = (
0o012700, # MOV #0176704,R0
0o012701, # MOV #0176704,R1
0o176704,
0o012740, # MOV #177000,-(R0)
0o012741, # MOV #177000,-(R1)
0o177000,
0o012740, # MOV #071, -(R0)
0o012741, # MOV #071, -(R1)
0o000071,
0o0, # HALT
)