MPF F11W floppy write protect issue (STE)

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ijor
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Re: MPF F11W floppy write protect issue (STE)

Post by ijor » Fri Dec 07, 2018 1:53 pm

exxos wrote:
Fri Dec 07, 2018 1:39 pm
The WP signal is set on bit 7 of the status register. So when TOS reads it, it sees a false WP signal because of ringing on the bus..
Not bit 7, bit 6. But yes, TOS could see a false wprot error when reading the status register. But if so you would expect general floppy malfunction. Even if ringing affects just a single bit, most programs read from the floppy shouldn't work.
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Re: MPF F11W floppy write protect issue (STE)

Post by exxos » Fri Dec 07, 2018 1:57 pm

ijor wrote:
Fri Dec 07, 2018 1:53 pm
Not bit 7, bit 6. But yes, TOS could see a false wprot error when reading the status register. But if so you would expect general floppy malfunction. Even if ringing affects just a single bit, most programs read from the floppy shouldn't work.
I was having read issues, also write issues hence the corrupt desktop.inf file causing chaos on my desktop, obviously different issue then WP signal not working correctly as the write happend. I would assume read issues would have been partly fixed by CRC checks. Though I never looked into how all that exactly works.
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ijor
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Re: MPF F11W floppy write protect issue (STE)

Post by ijor » Fri Dec 07, 2018 2:57 pm

exxos wrote:
Fri Dec 07, 2018 1:57 pm
I was having read issues, also write issues hence the corrupt desktop.inf file causing chaos on my desktop, obviously different issue then WP signal not working correctly as the write happend.
oh, I see.
I would assume read issues would have been partly fixed by CRC checks. Though I never looked into how all that exactly works.
No, CRC is something between the disk, the drive and the FDC. CRC doesn't protect transactions on the data bus. The data bus is assumed to be reliable.

Edit: typos
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