[Unmoderated] ArticiaS: mystery finaly solved ? | ANN.lu |
Posted on 08-Jul-2004 06:47 GMT by brotheris | 140 comments View flat View list |
Here's the summary of the last posts from hot topic. It may finaly put some dots on I's. Up to now we have heared a lot of small bits from variuos parties and finaly we can put the puzzle together. Read more about it.
I'll play Amon_Re of the past:
It all started when Chris Hogdes started explaining few things (in this thread and @226 comment).
During DMA transfers, the ArticiaS does not flag accessed memory as "dirty", therefore the CPU does not automatically know, that it has to update/flush its caches
Later (@ comment 247, 248 and others) Bernie Meyer explained how such a lack of feature (or call it a bug) affects stability, performance and may cause data corruption even in AmigaOS-like enviroment while using CachePreDMA()/CachePostDMA().
And then we discover quotes from ArticiaS documentation:
"The snoop cycle is used to probe the primary and secondary cache for updated data when the PCI
accesses DRAM. This is done to maintain data coherency between the Floating Buffer, DRAM and both
caches. The Articia S performs the Snoop cycle. When there is a snoop hit on a modified cache line in
either level one or two cache, the contents are written back directly to the Floating Buffer. A PCI Bus
master can subsequently later on fetch the data directly from the Floating Buffer. The Floating Buffer is
flushed back to DRAM during a PCI write cycle. The corresponding line in level one or level two cache is
thus invalidated. Snoops are hidden, meaning the CPU can continue its current data access without
being interrupted while the Articia S simultaneously queries both caches."
You can find similar information using google cache. It seems like some people lied. Is lack of Cache Coherency a bug or a feature (it was advertised that there is Cache Coherency, so it had to work) ? We may now put this case to rest.
|
|
List of all comments to this article |
ArticiaS: mystery finaly solved ? : Comment 26 of 140 | ANN.lu |
Posted by Johan Rönnblom on 08-Jul-2004 09:02 GMT | In reply to Comment 6 (Emeric SH): Emeric SH wrote:
> Peg2 wrote:
>> We want Amiga with real AmigaOS, and not Pegasos crap with an
>> emulator.
>
> Stick to the classic then. There is no spoon :)
Well, for people who for some reason or another absolutely want to run
OS4, I'm not sure "classic" is a better choice than the bugged A1.
Let's compare:
AOne does have serious DMA issues. But even with these issues, things
like disk speed is likely to be faster than most classic hardware. And
even if it would be a bit slower, this should be offset by the faster
CPU etc.
The DMA problems will probably also mean that drivers for various
peripherals won't be available. However, these peripherals are
probably not available on the classic either, so..
Ok, the A1 is rather expensive. But - a fully equipped classic machine
is hardly cheap either. If you can find one for sale, at all.
Considering how Eyetech and Hyperion won't even admit this DMA bug
exists, I wouldn't feel too assured buying products from them, that
they will take a responsible attitude should more problems turn up.
However, at least you do get a warranty for totally obvious defects,
which is probably more than you'd get if you buy a "classic".
So.. if you're choosing between A1 + OS4 or Peg2+MorphOS, of course
the latter option has a HW advantage. But if you for some reason
really want to run OS4 (maybe because you already own a MOS system and
want to try both :-) then I wouldn't say the A1 is uninteresting. It's
bugged and crippled but for running a novelty OS, it could do. |
|
List of all comments to this article (continued) |
|
- User Menu
-
- About ANN archives
- The ANN archives is powered by #AmigaZeux. It was updated daily (news last: 22-Oct-2004; comments last: 18-May-2005).
ANN.lu was created, previously owned and maintained by Christian Kemp, www.ckemp.com.
- Contribute
- Not possible at this time!
- Search ANN archives
- Advanced search
- Hosting
- ANN.lu was hosted by Dreamhost. Sign up through this link, mention "ckemp" as referrer and he will get a 10% commission on any account you purchase.
Please show your appreciation for any past, present and future work on ANN.lu by making a contribution via PayPal.
|