Posted By
JamesD
on 2013-07-31
16:36:00
|  Re: Z80 GUI: SymbOS
@Litwr
"IMHO This factor (2.2) is disputable. I have evidence from a man experienced with 6502 and z80 that this factor maybe up to 4 or even 5. IMHO it is about 3-3.5 because we can see the same games for 3.5MHz Spectrum and 1 MHz C64 where C64 used more advanced graphics and sound."
It's disputable if you compare instruction by instruction. But the benchmarks I've seen don't reflect that. If the 6502 even has to touch 16 bits (and it always does) the individual instruction advantage goes right out the window.
Compare compiler output and the 6502 really sucks.
The problem with comparisons between programs is usually apples and oranges since the CPUs aren't doing the same work. Since the Spectrum drives everything in software you have to be careful what you compare if the goal is comparing processors.
Elite should be a great comparison tool because it involves a lot of math, drawing lines, etc... right?
So compare Elite between the Spectrum and the C64. Yeah, it's a similar frame rate at a glance but the Spectrum doesn't flash lines like the C64. You know why? Because it's rendering to a buffer and then copying the buffer to the display on VBLANK. The Speccy is doing a LOT more work than the C64 and rendering at a similar frame rate. It's also delaying to a VBLANK rather than rendering every frame as soon as possible. That kinda throws out the "they run about the same speed and the C64 CPU is about 1/4 the MHz" argument. Apples and oranges.
Sort an array, draw a line with the same algorithm, move some memory around, draw some text rendered in software on a hi-res bitmap, etc... and then you are doing the same work... as long as the computer hardware isn't adding wait states for the CPU anyway because then results are system specific rather than CPU specific.
@gerliczer
The 2.2 speed difference is something that Spectrum users generally admit to.
In reality, it depends on what you are doing. Some things will be faster than others.
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