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VAX420: Added ROM patch to correct boot problem on MicroVAX 3100 M10/M20

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This commit is contained in:
Matt Burke
2019-05-08 01:02:54 +01:00
parent 0dff31427f
commit 650cfd4864
5 changed files with 16422 additions and 16401 deletions
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24
VAX/ka41a_patch.com Normal file
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$!
$! This procedure patches KA41A.BIN (V1.6) Boot ROM image to work under
$! the SIMH simulator
$!
$ PATCH /ABSOLUTE /NEW_VERSION /OUTPUT=KA41A.BIN KA41A_ORIG.BIN
!
! Test D - NVR
!
! - This appears to be a bug in the ROM code, which
! causes an endless loop if the NVR is not initialised.
! The subroutine loops until a particular value is found
! in the SIE register however the SIE is a constant and
! never matches the expected value. There are no other
! exit conditions from this loop. The KA41-D V1.0 ROM
! has the same subroutine however the loop is exited
! when the expected value is not found in the SIE.
!
REPLACE/INSTRUCTION 0284C = 'BNEQ 0000280E'
'BNEQ 0000285B'
EXIT
!
UPDATE
EXIT
$