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|ID||Category [?]||Severity [?]||Reproducibility||Date Submitted||Last Update|
|06798||Core||Critical (emulation)||Always||23 days ago||23 days ago|
|Tester||drencorxeen||View Status||Public||Platform||MAME (Official Binary)|
|Assigned To||Resolution||Duplicate||OS||Windows 10 (64-bit)|
|Version||0.192||Fixed in Version||Build||64-bit|
|Summary||06798: m6809 incorrectly handling opcode 0x104F|
On a real m6809 CPU if you run a opcode of 0x104F the real 6809 will ignore the 0x10 opcode part of the instruction and will process the opcode of 0x4F which on a m6809 is a CLRA.
Please test on coco3, coco1, coco2.
|Steps To Reproduce||
Created a test assembly language program to load register D with $FFFF, then issue a 6309 instruction CLRD, then after that writing register A and register B to specific memory locations and using basic to peek and print the values should yield a 0 for A and 255 for B, but the m6809 core in MAME ignores both bytes of the CLRD where it should have only ignored the 0x10.
I am including a DSK image for testing.
Steps once disk image is mounted in drive 0:
On real CoCo 1, 2, 3 with a real m6809 in it the outputs as follows:
On emulator outputs:
So the 6309 instruction CLRD (0x104F) the (0x10) is ignored on a real m6809 CPU and thus it still processes the (0x4F) part of the instruction and does a CLRA.
I have tested this on a system that does in fact have a real m6809 on it and thus I know in this case how the emulation for the m6809 is not handling this situation correctly.
|Affected Sets / Systems|
6309.zip (695 bytes) 23 days ago Uploaded by drencorxeen
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