Re: [hatari-devel] IKBD regression with EmuTOS

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On sunnuntai 10 helmikuu 2013, Nicolas Pomarède wrote:
> On 10/02/2013 19:29, Vincent Rivière wrote:
> > Ok, EmuTOS will need fixing if $80 $01 really answers with $f1.
> > But that does not explain why it works fine on real hardware.
> 
> In Hatari, after the first start, the acia's clock is started only when
> writing $96 to $fffc00. If you receive byte from the ikbd before the
> acia is set, this will create the observed error under emutos (due to
> the overrun). If you then reset Hatari, the acia's clock remains
> initialized, so the ikbd will work correctly this time.
> 
> The ACIA's doc is not clear on the value of bits 0 and 1 of $fffc00
> after a reset. From what you say, if it works on real hardware, then it
> would mean that the acia processes serial data after the first start
> (bits 0 and 1 would be 0 and clock divider would be 1).

Based on Vincent's mail on emutos-devel, real hardware in this case
was STE.  Does STE ACIA behave differently?

(It's also possible that somebody who has replaced his ROM chips with
EmuTOS might have modified his machine also in some other ways. :-))


> I will modify the acia's code to behave like this when Hatari starts,
> but still you should read $fffc02 after a reset when RDRF is set, else
> you might get problem in other cases.


	 - Eero