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Hi, I am not sure this qualifies as an issue. I would generally put this in a discussion tab but there does not seem to be one for this repository. Anyway, I am trying to execute the following code on an instance of the class CPUSpeedLimit:

self.cpu.memory.load(0x100, bytearray([
    # A = atoi(*(0x1000)) + atoi(*(0x1001)):
    0xB6, 0x10, 0x00,   # LDA       (extended)      0x1000
    0x80, 0x30,         # SUBA      (immediate)     0x30 (48 in base 10)
    0xF6, 0x10, 0x01,   # LDB       (extended)      0x1001
    0xC0, 0x30,         # SUBB      (immediate)     0x30 (48 in base 10)
    0xF7, 0x10, 0x02,   # STB       (extended)      0x1002
    0xBB, 0x10, 0x02    # ADDA      (extended)      0x1002
]))

self.cpu.program_counter.set(0x100)

self.cpu.run(target_cycles_per_sec=1)

But upon running it, I get the following error:
File "MC6809/MC6809/components/mc6809_base.py", line 787, in instruction_NEG_memory raise RuntimeError("Wrong PC ???") RuntimeError: Wrong PC ???
I am not sure about what causes this error. Again, I apologize if it is the wrong place to ask but I did not really know where to put my message. Thanks in advance.

Steps to reproduce:

Assemble and run the following code:

LDA #$91
ADD #$91
DAA

What happened?

Carry was reset.

When similar code was used for multi-byte decimal addition, it yielded incorrect results.

What was expected?

Carry should be set. DAA keeps the carry flag set if it was set beforehand, see the mc6809 emulator sources for comparison: https://github.com/spc476/mc6809/blob/master/mc6809.c#L420 or the official Programming Manual: https://archive.org/details/bitsavers_motorola68_13419254/page/n83/mode/2up

C – Set if a carry is generated or if the carry bit was set before the operation; cleared otherwise.

After some research, I noticed that this is a common bug in many 6809 emulators.