Accelerator without ram performance.

[utri007]

I have TerribleFire 520 accelerator wich has 68020 cpu, and it has no RAM it's own. Fast RAM is in GVP HD8+ ram & SCSI board.

This way it is a 1,68x faster than original A500.

OK, I can really understand this, BUT

I had a Supra turbo with very similar setup. I doesn't have RAM it is own and it uses external fast ram on side connector.

It was 5,89x faster than A500

How did Supra turbo was so much faster? Could 16kb cache explain this?

http://amiga.resource.cx/exp/supra28

[utri007]

It is 37mhz

[utri007]

Here

[utri007]

I know that there are performance problems with accelerators like this. But I wonder what makes difference between this and Supra accelerator? Can it really be that 16kb data cache wich supra has?

[utri007]

Cache is effectively fastram wired directly to the CPU. They can work both as fast as each other.

If you have sidecar fastram and a cpu socket turbo board, the cpu must talk to the fastram through the Amiga500 bus, which is working at a much slower speed. So performance chokes.

It's like if you have 10 lane 70mph highway and then make it all go over a one-lane stone arch bridge with traffic lights. Big bottleneck.

I know, but why Supra is that much faster? I t doesn't have ram, ram is in sidecar and CPU is 68000, biggest difference to Terrible Fire 520 is tiny 16kb data cache.

[utri007]

Yes you did. Sorry. Cache seems to make huge difference even if ram is in side car. Wich is somewhat weird.

[utri007]

TF520 makes A500 1,7x faster than it originally was. Price is also very low, so it is very nice card for a price.