• Hello, Guest! Welcome back, and be sure to check out this post for more info about the recent service interruption and migration.

ThunderStorm, Thunder II GX, DSP multiple processor run


Well-known member
I have 2 Thunder II GX cards and one ThunderStorm DSP card. All this cards have two AT&T DSP 16A chips.

I tried to run all 6 processors at the same time but that doesn't work. Mac use only the first card that is installed nearest to the PSU and use only that one. The ImageProccessor control panel identifies all cards and processors installed but only first card is used.

The cards were installed in my Quadra 950, 256 RAM, 2x 2 GB HD drive, like this

Slot A - Radius PrecisionColor 24x
Slot B - Thunder II GX
Slot C - Thunder II GX
Slot D - ThunderStorm
Slot E - JackHammer


Tested it with PicturePress 2.5 and Photoshop 2.0.1. The Thunder II GX cards were for few seconds faster than the ThunderStorm DSP card.

Without hardware acceleration PicturePress opened sample ship file in 5.6 secs. When used DSP cards the ThunderStorm opened the same file in 1.8 sec, and the Thunder II GX in 1.5 seconds.

When using Photoshop and Gaussian blur at 10 px, the StormCard used 14 sec, Thunder 12 sec.

This was just a quick test to se if the Mac can use all DSP processors at the same time, but as I said that is a no go :)




Well-known member
No RadiusRocket with DSP? I'm disappointed. ;)

That's a lotta DSPs in there. I wonder if a plugin could be written to be multi-card DSP aware. Clearly it can use more than one DSP on a single card.


Well-known member
Good question, ... it was running System 7.6.1 and I think it reboots itself to 32 bit automatically at startup ...


Well-known member
System 7.6 and higher requires 32-bit addressing, so it's always enabled.

As for the DSPs, too little software took advantage of them to justify the cost. I recall a period in the early 90s when DSPs were considered "miracle" chips that could solve all the world's mostly floating point computing problems. They landed up being difficult to program and pretty darned expensive. Pretty sure very little software took advantage of the Atari Falcon's Motorola 56000 or the Quadra AV's AT&T 3210. Raw CPU horsepower (namely PowerPC and the original Pentium) very quickly eclipsed them.


Well-known member
The first use of DSP's were probably for sound creation and converting tiff into jpeg. After that they were used widely in motion video compression.

Photoshop 2.5 had a few DSP plugins for example. So did some sound cards and DVD decoders.

There was a small period of time where they were very useful for people doing specific tasks that adding them via Nubus card was worth the price but advances in CPU power pretty much killed them off. Same thing happened to FPU's like the Weitek.


Curious, I wonder if the chips on the GX card are filling its Video buffer directly while only talking to the CPU over NuBus? ThunderStorm is sending the same info across NuBus to CPU and a VidCard? Might that account for the speed difference?