Re: [hatari-devel] The WD1770 "Motor on" line

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 24/11/2014 22:22, Roger Burrows a écrit :
> When EmuTOS is booted under Hatari 1.8.0 with both floppies enabled, the green
> LED indicator for drive B stays on, showing the drive is still selected.  The
> normal EmuTOS behaviour after a drive has been selected is to leave it selected
> until the MOTOR ON bit in the WD1770 status register is zero; at that time, all
> drives are deselected.
>
> The MOTOR ON bit is checked in the VBL handler, and appears to be always set
> on; thus the drive is never deselected.  According to my WD1770 spec, if the
> device remains idle for 10 revolutions, the MOTOR ON line will go back to 0,
> but this doesn't seem to happen with the emulated WD1770.
>
> This code worked fine under 1.7.0.

Hi,

this was already reported by vincent and discussed in the thread "LED 
with empty floppy drives" and my answer from 9/6/2014.

Basically, Hatari's behaviour is the same as my STF and STE when no 
floppy are inserted in both drives.

Note that your reading of the doc is incomplete : the led/motor will 
indeed turn off after the WD1772 counts 10 revolution. But the problem 
is that the WD1772 can't count revolution unless a floppy is inserted in 
the drive :(

So, this means a selected drive where you sent a command (restore, seek, 
....) will never turns off. You can wait several hours, it will keep on 
spinning ; it's only if you insert a floppy that the drive will complete 
its command and clear motor after 2 sec.

It's wrong at Emutos level to assume the motor bit will eventually be 
cleared ; if there's not floppy it will stay on forever. So, you need to 
have an extra timeout > 10 revolution = 2 sec to unselect the drive in 
all cases, even if motor bit was not cleared.

This "worked" in Hatari 1.7.0 because it was not correctly emulated :)

Nicolas