| Re: [hatari-devel] floppy media change on TT |
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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] floppy media change on TT
- From: Christian Zietz <czietz@xxxxxxx>
- Date: Thu, 30 May 2019 15:03:14 +0200
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Nicolas Pomarède schrieb:
> As I don't have a TT to test this myself, could someone read the content
> of FFFA81 when a floppy is inserted in the internal drive and when the
> drive is empty ? (I don't know if this bit is inverted before going into
> MFP GPIP6).
As promised, I did some tests on my TT. It's not the original floppy
drive, though. I found the following:
- The drive only signals a disk change on pin 34 when it is selected via
the corresponding drive select signal.
- If the drive is selected, it will drive pin 34 low in case of a disk
change. Much like the other signals on the floppy drive interface, this
is an open-collector output. A pull-up resistor is located in the TT.
- The signal is inverted before going into the TT-MFP. Therefore, bit 4
gets set to '1' in case of a disk change.
- The drive will only reset the disk change signal after receiving a
step pulse. Thus, if the head is already on track 0 and TOS just reads
the boot sector, FAT and root directory from track 0, the disk change
signal will stay asserted (=line low, bit '1') even after TOS has
finished detecting the media change.
Hope that helps,
Christian
--
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
WWW: http://www.chzsoft.de/
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