A new Zorro III memory board

[matthey]

The Mediator, Prometheus, and G-Rex can take PCI cards with plenty of FAST graphics memory. Even though there would be no drivers for these "newer" gfx cards, it shouldn't be too difficult to find there memory address and add it to the free memory. I'm surprised no one has done this. I thought about doing it at one time as I have a Mediator but I would have to deal with Elbox and sign their exclusive non-disclosure agreement for their super top secrets. It's much more important to keep the competition at bay in this huge Amiga market than have lots of software for their products after all. Too bad they have this closed minded attitude as they make excellent hardware.

[matthey]

Sure, the Mediator would be limited by Zorro3 speed. The speed of the memory on a gfx card would not be the bottleneck is what I was trying to say. The memory would be faster than almost all existing Zorro memory cards. It would be relatively slow for a PowerPC and maybe even a 68060. Faster CPU local memory would be used first. It would certainly be faster than any kind of virtual memory.

[matthey]

mboehmer_e3b wrote:

(1) memory on gfx cards is optimized for writing. It is dead slow on reading, as usually you don't read it in normal operation. Reading on PCI may lead to delayed transactions, with penalty in time and the risk of Buster timeouts (can be seen when accessing PCI-PCI bridges or FlashROM on gfx cards).

Slow is relative. Zorro3 speeds are slow compared to what a gfx card can move around. The Mediator already uses a part of gfx memory for 10/100 nic cards which is read when it's transferred to the Amiga memory. The 10/100 nic cards aren't blazing speed but faster than Zorro II 10mbit cards in most cases. Do the buster problems occur with a Revision 11 buster?

(2) no gfx mem access without gfx processor initialization. The gfx mem is only accessible via the GPU, and this beast needs to be setup correctly.

Are all gfx cards this way?

(3) Endianess. Some gfx cards change the byte order of the memory when changing screen modes. In case you switch to a new screen, your memory gets scrambled. Bad idea.

I was talking about using a 2nd gfx card just for the memory on it. No screens = no byte order swapping. Some gfx cards probably wouldn't work well as an Amiga "memory card". Choose ones that do. E-bay has tons of used PCI gfx cards for next to nothing.