Re: [hatari-devel] Manual update

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

On 1/2/20 12:42 PM, Christian Zietz wrote:
> Eero Tamminen schrieb:
>
> > (Except that I just noticed that I missed
> > blitter for MegaST.)
>
> Also, in the table, the "X" for RTC was incorrectly placed in the STE
> column, instead of the MegaST one.

Thanks, I missed that when switching columns around.  Fixed now.


> > Btw. System dialog section mentions that
> > the emulated ST add-on blitter is Ricoh,
> > but Mega-ST one is IMP one.
>
> If it was worded like this in the manual, it would certainly be wrong.

Text is following:
"The Mega-ST was an slightly improved version which also provided the 
so-called blitter chip (for accelerating certain graphic operations) and 
a Real Time Clock (RTC) chip. A note for experts: Hatari emulates the 
Mega-ST with the so-called IMP chipset, while the normal ST is emulated 
with the Ricoh chipset. This gives a slightly different behavior between 
the two machine types with regards to bus errors."

(I had assumed that chipset above referred to
blitter, as ricoh & IMP had elsewhere been
mentioned in connection to blitter.)


> The difference between Ricoh and IMP does *not* refer to the Blitter but
> to the (rest of the) chipset. There are observable differences in the
> Glue (regarding which addresses cause a bus error) and in the MMU
> (regarding handling of certain memory bank combinations).
>
> Blitters, in particular, were never even made by Ricoh. Known Blitter
> manufacturers are ST (SGS Thomson), GE/RCA, National Semiconductors and
> IMP.

Any proposals on how to clarify the text in the manual, to indicate that 
"chipset" refers to
differences in Glue & 68000 "MMU"?


> Atari also contacted further manufacturers about the Blitter, but
> they never appeared in the wild -- if they were ever produced. Until
> now, between the manufacturers no difference relevant to emulation is
> known. (Afair, Hatari doesn't emulate some weird Blitter corner cases
> correctly, anyway.)


	- Eero