does kickload into fastram improve performance of libs and devs ?

[elz]

This is a simple question that I never could find a simple answer yet : Does a device or library run faster if it's in FastRAM or ROM ?

I removed the ChipRAM options since it's probably slower and if you rely on ChipRAM you probably want to save it as much as possible and keep everything you can on ROM. My understanding of the amiga world and it's memory is that it's versatility is often impaired with matter of tradeoff. You can adapt it as a matter of priority to suit your need.

When it come to custom ksroms, my first though goes to iconlib. I'm sure Peter Keunecke does everything that is humanly possible to keep the footprint of it's excellent icon.library as small as possible. But when I ponder about putting it in a custom rom, I can't help but wonder if it would make it display the icons slower ?

Do you have experience, similar thread/post or benchmark to share about it ? Thank you !

[Bruce Abbott]

This is a simple question that I never could find a simple answer yet : Does a device or library run faster if it's in FastRAM or ROM ?

It's not such a simple question, because it depends on several factors that vary depending on the particular machine.

On a standard 16 bit Amiga (A1000/500/600/2000) the ROM and RAM are both 16 bit and run at the full CPU bus speed with no custom chip contention, so there should be no difference. However FastRAM usually has dynamic RAM chips that need refreshing, which typically steals ~1-3% of the bus cycles making it a bit slower than ROM. But the ROM routines also access RAM occasionally so the total effect will be a bit less. Bottom line is the difference is small enough that you probably won't notice.

On 16 bit machines with accelerator cards the system ROMs still run at standard 68000 bus speed, but if the FastRAM is on the faster local CPU bus it will be much quicker.

Stock A1200/3000/4000 have 32 bit ROMs (2 ROM chips) so the difference isn't that great, and their CPUs have instruction caches which also speeds up ROM access. But the CD32 only has a 16 bit ROM so copying it into FastRAM makes a big difference. Of course these machines also go a lot faster when using advanced accelerator cards with local FastRAM.

Many accelerator cards have a 'maprom' function which copies the system ROM to FastRAM on power up and then makes it appear like ROM, but much faster. On machines with 16 bit ROMs this noticeably improves the speed of system operations, including displaying icons on WorkBench.

My understanding of the amiga world and it's memory is that it's versatility is often impaired with matter of tradeoff. You can adapt it as a matter of priority to suit your need.

The main 'tradeoff' is that ChipRAM is needed for graphics, sound, and blitter operations, and only 0.5/1/2MB is available so it is a valuable resource. Also the CPU is halted during intensive custom chip DMA operations (blitting images, high screen resolutions etc.) so it makes sense to put everything else in FastRAM if possible.

In the old days this did often result in 'impaired versatility' because FastRAM expansions were expensive and many Amiga owners were too 'poor' to afford them. That's not true now, so the only reason not to have a good amount of FastRAM today is for compatibility with buggy software that can't handle it.