| Re: [hatari-devel] Re: [Emutos-devel] Aranym blitter |
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Thorsten Otto schrieb:
> Am Donnerstag, 8. Juni 2017, 16:34:57 schrieb Nicolas Pomarède:
>> It shows that word
>>and bytes accesses don't give bus error between FF8A00 and FF8A40
> Thats the case for other io regions too, but that does not mean any meaningful
> values are returned. The doc says for example that the address registers can
> be accessed with either word or longword accesses.
Byte writes to the Blitters word registers are simply discarded, i.e.
the register value doesn't change. I tested this on real hardware and it
can also be seen in the Blitter schematic. (Only when /RW, /UDS and /LDS
are low the internal write signal XWW for writing word registers is
generated.)
Byte reads seem to work, i.e. the correct value is returned. However, as
Thorsten and I have already mentioned, Atari says word or longword
accesses have to be used, anyway.
Regards
Christian
--
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
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