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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] Dynamic Bus Sizing and I/O Register Access
- From: Thomas Huth <th.huth@xxxxxxxxx>
- Date: Fri, 12 Jan 2024 19:14:50 +0000
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Am Fri, 12 Jan 2024 19:58:00 +0100
schrieb Andreas Grabher <andreas_g86@xxxxxxxxxx>:
> > Am 12.01.2024 um 19:41 schrieb Thomas Huth <th.huth@xxxxxxxxx>:
> >
> > Yes, right. This basically depends on what your I/O hardware (like the
> > "glue" on the ST) is doing with the accesses on the bus.
> >
> > Do you know what's supposed to happen if the bootloader write a 32-bit word
> > to 0x02010000 ? For example, if it wrote 0x12345678 to that address, which
> > byte is supposed to end up in the brightness register?
> >
> > Thomas
>
> In this example on real hardware (68030) it would write 0x78.
Ok, that's quite different compared to the I/O registers on the Atari (but
perfectly possible if the NeXT hardware has been designed that way). I think
in that case you have to read the value from
IoMem[(IoAccessCurrentAddress + nIoMemAccessSize - 1) & IO_SEG_MASK]
instead.
HTH,
Thomas