From: micro@imada.ou.dk (Klaus Pedersen)
Newsgroups: comp.sys.amiga.hardware,comp.sys.amiga.advocacy
Subject: Re: Atari Falcon (wasn't: Amiga Falcon)
Date: 14 Apr 92 00:17:01 GMT
Organization: Dept. of Math. & Computer Science, Odense University, Denmark


>>Where's the time going? The TT and SST using fast RAM do 4/1/1/1 bursts.
>>TT at 32MHz, SST at anywhere from 25 to 50MHz.

daveh@cbmvax.commodore.com (Dave Haynie) writes:

>The hell they do.  The TT (I dunno anything about any SST) ran a 32MHz 
>processor connected to a 16MHz memory design (in fact, the original TTs had
>this hacked in as a tower, though eventually they put the circuitry on
>the motherboard).  Even if they had managed 4/1/1/1 at 16MHz, that would
>translate to 8/2/2/2 at 32MHz.  A 2-clock burst is about the best you can
>do with a single bank of 80ns DRAM at 32MHz, unless you go to nybble mode
>DRAM (most vendors don't, because you can then only upgrade in 4MB chunks;

They do use nybble mode RAM. The Slow ram in a TT is 64 bit wide and can be
accessed 4 times per micro sec. That is 8 32 bit words per uS. If what you
say is true then Fast ram is slower than Slow ram.
That is what is needed to do 1280x960 noninterlace 70Hz or 320x480x256 
noninterlace 60Hz! 

>some of the GVP boards used this, as did the NeXT '030 system).  However,
>8 clocks is downright pitiful for a 32MHz system, which is why the TT runs
>most benchmarks slower than the A3000, even though it has, on paper, a
>faster clock.

The Hell it ain't!!

Remember that the TT comes _standard_ w. a 32MHz 68882!


-Klaus



-------------------------------------------------------------------
Here is the original post from atari Aug 89
-------------------------------------------------------------------

From: apratt@atari.UUCP (Allan Pratt)
Date: 31 Aug 89 01:19:58 GMT
Organization: Atari Corp., Sunnyvale CA

Here's some really straight scoop about the TT from inside Atari:
[...]
There are a number of ways to expand the TT: you can add 2MB of
dual-purpose (video and CPU) RAM, or 10MB when 4Mbit chips are
available.  You can add 4MB of REALLY FAST 32-bit nybble-mode RAM (not
video-capable), and there's the VME bus.
[...]
cycle.  For dual-purpose RAM, around half the bus cycles go to the 
video or refresh.  Therefore, the CPU gets around two million MEMORY
ACCESSES per second, or 2MHz.  There are other architectural details
which make it a little faster than that.  And remember, each access
gets you 32 bits, not 16 as on the ST.  Also, since the CPU is
allocated half the bus cycles, it isn't ALWAYS postponed by video or
refresh: it might try to access the bus just as its turn comes up, and
not wait at all.  Therefore dual-purpose memory accesses run at MORE
THAN 2MHz.

"Fast" RAM does not have video taking up any of the cycles, so you
don't have to wait for that.  It takes 4 or 5 clocks (I think) to set
up a fast-RAM access, but "nybble mode" means that the CPU fills its
cache in "burst mode" at one cycle per subsequent access.

The VME logic introduces one wait state, so a VMEbus access takes 5
clocks. (Your mileage may vary: VME cards vary widely in response
time.)  But, again, you won't be held off the bus by video.  VME in the
TT shown in Germany is A24/D16 (24 bits of addess, 16 bits of data).

[...]

>Does it have a Blitter ?

No need for one.  The reason for the Blitter is to remove instruction-
fetch overhead from memory operations, and with the 68030 on-chip
cache, the TT does just fine without it.

[...]
============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt

---------------------------------------------------------------------------
End of quote...