[tralarpa]

I wonder how much faster the ARM2 would have been compared to the 68k in a first-generation Amiga. The Amiga's chip memory only delivered 7 MBytes/s, shared between the CPU and the chipset! With its 32-bit instruction words, the ARM2 would have been very far from its theoretical performance.

[lproven]

> I wonder how much faster the ARM2 would have been compared to the 68k in a first-generation Amiga.

Considerably faster. I looked at both (and the ST) and bought an Archimedes.

ARM chips benchmarked from the ARM2 up to the RasPi 3B+:

https://stardot.org.uk/forums/viewtopic.php?t=20379

68000 benchmarks around that time:

http://www.faqs.org/faqs/motorola/68k-chips-faq/

ARM2:

Dhrystone/sec 5463

68000 @ 8MHz:

Dhrystones

68000 2100

MIPS

https://en.wikichip.org/wiki/acorn/microarchitectures/arm2

https://en.wikipedia.org/wiki/Instructions_per_second

ARM2: from 6 to 10 million instructions per second, depending on instruction mix

68000: 1.4 MIPS typical.

(For comparison: Intel 8086 at the same speed, something like 300 Whetstones, 0.5 MIPS. So either of them stomped all over a comparable x86 machine from that time.)

So, very roughly, ARM2 was between 2-3x faster in typical use.

Note:

. Neither CPU could do FP in hardware.

. Neither had cache memory.

. The Amiga had a lot of complex hardware acceleration for graphics; the original ARM2 machines from Acorn (Archimedes A2305, A310, A400) had essentially none.

So, Amiga games could do things that on the Arc required raw CPU, typically done careful hand-coded assembler.

[tralarpa]

Yes, but that's my point: the ARM2 cannot get faster than 1.25 MIPS in an Amiga because of the memory bandwidth (assuming that the CPU uses 5 MBytes/s of the available 7 MBytes/s that it has to share with the graphics chipset).

[memsom]

Well - I used Archimedes computers with ARM2 and owned an Amiga 500+ and honestly, I couldn't tell you the Arcie was faster. It certainly didn't have the custom chips, so it is probably not a fair comparison.