Date: Thu, 29 Mar 2001 23:58:28 +0200
From: ELBOX support@elbox.com.pl
Subject: [Fwd: [Amiga-Mediator] Watch out: Insider's comments on G-Rex]

I am sending you a message delivered today to the Mediator news-list.
You may find it interesting.

Darek Dulian
ELBOX COMPUTER

-------- Original Message --------
Subject: [Amiga-Mediator] Watch out: Insider's comments on G-Rex
Date: Thu, 29 Mar 2001 23:00:40 +0200
From: ELBOX support@elbox.com
Reply-To: Amiga-Mediator@yahoogroups.com
Organization: ELBOX COMPUTER
To: Amiga-Mediator@yahoogroups.com, G-REX@yahoogroups.com

Hi,

We have received a number of inquiries about whether the
SharkPPC G3/G4 card could be used in the G-REX busboard.

Here is the response to clear up these doubts:

The SharkPPC G3/G4 card is a PCI-standard card which
meets all the requirements of the PCI 2.2 specification.
We are using PCI CPC710 bridge chips by IBM
(http://www.chips.ibm.com/products/powerpc/chips/)
in SharkPPC cards.

Designing the Mediator busboard, we have foreseen mechanisms
to enable full use of the functions offered by the MPC710
interface, which operates as the Mediator PCI  busarbiter.
This required, firstly, implementing the full system for
busmastering management in the PCI slots of Mediator
and the full implementation of interruption system specified
by the PCI standard.

The G-REX busboard design (called PREDATOR in some countries)
has been made available for some weeks now.
The G-REX design is based on the single-slot simplified bridge
designed only with the aim of supporting a graphic card;
this bridge was previously composed within the BVision card.
Applying this bridge in the G-REX busboard resulted in a number
of limitations. The most important of them are:

1. Complete lack of support for the busmastering (DMA)
   between PCI slots (the lines controlling busmastering -
   GNT#, REQ# are not physically connected to the 2nd, 3rd,
   4th and 5th G-REX slot).

   This makes the operation of PCI cards impossible, which
   cannot use their mutual resources without overloading the
   processor.  Therefore, the G-REX busboard is not capable
   of offering what Elbox presented in the WOA2000 fair, where
   a TV card in the PCI slot was writing as busmaster data to
   Voodoo3 graphic card at full speed without intermediation
   of the processor.

2. Lack of a parity control system (the PAR parity line
   is not physically connected to the control logics of the
   busboard).

   It means that many standard popular PCI cards will not run
   in this busboard.

3. Reduction of the interruption system from 4 to 1
   - the interruption lines (INTB#, INTC#, INTD#) are not
   physically connected to PCI slots.

The processor card could be then installed only in the 1st
slot, the one to which GNT and REQ signals are connected
(which enable taking over controlling address/data buses).

However, as the G-REX busboard does not support (DMA)
busmastering between slots, co-operation of the PCI processor
cards with any cards working in this mode is impossible.
All the currently produced TV, USB, FastEthernet and more
advanced music cards (e.g. Sound Blaster Live) work solely
in the busmastering mode.

These limitations in G-REX make installation of any advanced
processor cards in it useless and ineffective.

I am really embarrassed to read letters from people who
-- having no idea about hardware -- give their opinions on
various products or designs.
Elbox is a company present in the electronics for many years.
Elbox employs high-standard engineers electronicians
and programmers.

We are not in the habit of commenting devices or software,
but here we make an exception, as the level of misinformation
in the ML like this one reached its critical level.

Best regards,
Darek Dulian
ELBOX COMPUTER, Support Department

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