Spinrite 6.1 Rc5.05 500gb HDD Attempt to execute illegal opcode

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    To obtain direct, low-level access to a system's mass storage drives, SpinRite runs under a GRC-customized version of FreeDOS which has been modified to add compatibility with all file systems. In order to run SpinRite it must first be possible to boot FreeDOS.

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New member
Jan 1, 2024
Hi, This happened, it is my D: drive, it is admittedly old and has miscellaneous data on it. It was about halfway through first row of dots. I was scrolling through the screens and error occurred.

op code.jpg
@Noswal : THANK YOU for the report!

I'm glad that you provided the extra detail that this occurred when you were scrolling through the screens. That gives me a good clue about where to look for the trouble... and maybe the opportunity to recreate it. I've opened an “Issue” for this over in GRC's GitLab so I will pursue it! Thanks again!
@Noswal: I just found and fixed a bug I introduced (along with a new feature) back with RC4. The new feature added logging of the number of over-temperature events that occurred on a drive between other log entries while SpinRite is running. That bug messed up SpinRite's screen display code. So I'm wondering whether that drive might have experienced an over temperature event while you were running it? That event would queue up a pending log entry that definitely would mess up SpinRite's code. If you don't recall ever seeing that I'll setup an automatic screen switching test to see whether I can make SpinRite misbehave. But, for what it's worth, we haven't seen in instance of a crash like you've reported before... and the over-temp event would definitely have been a likely cause. Thanks!
Hi, I ran SpinRrite again on that drive yesterday, without viewing the other screens, found 3 errors at end of drive.
HWinfo64 records drive maximum at 43C, average 39C. Whatever it was on my drive that caused the error am very glad to have been able to contribute to SpinRite's development.
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