HP 64746 User Manual page 171

Looking at the trace we see:
Trace List Depth=512
Label: Address
Base: hex
----- ------- ---------------------------------------------------
-014 00040C MOVE.W
-013 00040E 3F02
-012 000410 0832
-011 000412 MOVE.W
-010 800832 3F02
-009 000414 0001
-008 000416 0830
-007 000418 MOVE.W
-006 800830 0001
-005 00041A 0001
-004 00041C JSR
-003 00041E 0446
-002 43FFFE 0001
-001 43FFFC 041E
STATUS: M68302--Halted
What to look for:
Label/Base -007
Label/Base -002
Label/Base -001
Configuring the Emulator for In-Circuit Operation
Offset=0
Opcode or Status w/ Source Lines
mnemonic
#03F02,00832(A0)
sprog rd word
sprog rd word
#00001,00830(A0)
sdata wr word
sprog rd word
sprog rd word
#00001,-(A7)
sdata wr word
sprog rd word
0000446
sprog rd word
sdata wr word
sdata wr word
Emulation trace halted
A push of 0001 onto the stack is initiated. The stack
pointer is already set to 44000H. The memory below there
is accessed using chip-select 1, but the registers for
chip-select 1 have not been initialized yet.
The processor does a write of 0001 to location 43FFFEH as
a result of the instruction at -007, but because the the
chip-select that would provide DTACK has not yet been
initialized, the cycle is not terminated normally. The
1.02mS time count is indicative of an internally generated
bus error (BERR).
Because of the bus error in the previous cycle, the 68302
will immediately begin to process a bus error exception.
The first thing it will try to do is write the low word of the
program counter value to the stack. But again, since the
chip-select register has not been initialized this stack write
will also fail with a bus error, hence the double-bus fault!
Chapter 5: Plugging into a Target System
More data off screen
IAC
IAC
time count
relative
---------
640 nS
600 nS
640 nS
600 nS
280 nS
280 nS
320 nS
320 nS
240 nS
320 nS
320 nS
320 nS
1.02 mS
1.02 mS
........
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