Re: [hatari-devel] LED with empty floppy drives

[David Savinkoff <dsavnkff@xxxxxxxxx>]

----- Nicolas Pomarède wrote:
> Le 04/05/2014 19:48, David Savinkoff a écrit :
> 
> > I'm curious to know how the floppy LED is implemented in the STF.
> > Is the LED connected to the M51017AP IC, or is it connected to
> > something else?
> 
> I don't know, would need to find schematic for this.
> 
> > Note that the LED is connected to the M51017AP 'in use pin'
> > in the SF354.
> 
> Problem is that in the doc, we don't know how 'in use' is build, so 
> maybe different manufacturer had different meanings.
> 
> > Note that the external double sided SF314 is probably very similar
> > to the SF354... and the LED stays on.
> >
> > Maybe Atari TOS has a M51017AP 'in use' Bug for double sided disks.
> > Note that EmuTOS can be made without this bug.
> >
> > Hatari may have to emulate when the floppy disk is busy by checking
> > the floppy disk bus lines to know when the LED is on.
> >
> 
> Even with the SF354, I'm not sure the 'in use' led signal is only 
> related to activity on the bus line (do you mean bits transfer ?).
> 
> We can see that on normal operation (disk inserted), the led is on even 
> during the 1 sec spinup phase ; during this spinup, there's no activity 
> on the bus, except the INDEX signal on each round.
> If led was related to index signal too, the it would be blinking very 
> fast during the spin up phase.
> 
> 
What I meant by the floppy bus is:

pin  1 -- Read Data
pin  2 -- Side 0 Select
pin  3 -- Logic Ground
pin  4 -- Index Pulse
pin  5 -- Drive 0 Select (drive led on/off)
pin  6 -- Drive 1 Select (drive led on/off)
pin  7 -- Logic Ground
pin  8 -- Motor On
pin  9 -- Direction In
pin 10 -- Step
pin 11 -- Write Data
pin 12 -- Write Gate
pin 13 -- Track 0
pin 14 -- Write Protect

I looked at the schematics and the M51017AP data sheet.
It appears that the LED is turned on by simply selecting
pin  5 -- Drive 0 Select and/or pin  6 -- Drive 1 Select
Thus, this is a TOS BUG.
Furthermore, all that Hatari needs to do is turn the LED
on or off for the respective floppy drive by checking
IO-A1 and IO-A2 on the YM2149 to select the floppy
drives.

You should be able to turn the drive LEDs on and off
individually by writing to the YM2149.

With this information, someone Will (if they haven't already)
write a program to flash the floppy drive LEDs. Hatari must
be able to emulate this...---... ...---...