Posted By
MMS
on 2016-08-22
15:03:31
 |  Re: Mandelbrot and Commodore computers
I made some tests, though due to other activities I could not wait the several hours long full results.
(ouch, on an Amiga a complex raytrace HAM image rendered in 10-12 hours).
Summary: Austrospeed Compliler can double the speed of the already well optimized program
Actually the fractals and Mandelbrot/Julia,etc are very close to my heart, as my thesis in 1996 was made from this topic and wrote one of the very first Mandelbrot generators on PC with SVGA 256 color with fully mouse controllable GUI (can select new area with mouse, plus different color palettes for iterations, palette animation,+JMJ MOD music in the background, selectable fractals.  )
But due to the fact that Plussy had no such processing power, I made no trials to convert my Pascal PRG, though sprite (mouse) emulation and SID music playback is not a miracle any more
So, back to the topic:
I made a short test, how we may speed up the mandelbrot generator on Plus/4.
As we have no SuperCPU, I tested other speed up methods we discussed in the past, and the impact of BASIC Compilers.
As I have limited time, I just measured the very first 5 lines to be drawn.
I know very well, than the later areas are much more calcuation intensive, but hey, I have some life too 
Results to calculate and draw the first 5 lines:
original Mandelbrot V3.5 PRG 00:04:45 (4 minutes 45 seconds)
optimized Mandelbrot 00:04:44 (almost no impact)
(integers (%) used in FOR loops, variables used for comparisons io fix values)
(I made a mistake too: Renumbered it with 10, so the GOTO uses higher numbers in my version, make it slower a little)
AustroSpeed compiled orig.V3.5 00:02:20 (double speed, well visible improvement)
Austrospeed compiled optimized 00:02:16 (integers in FORs seems have some, but small impact)
AustroCONV tool from SVS: unfortunately it generated a PRG with incorrect SYS value, compiled and cracked PRG could not start, the value in the SYS command was just too high. Looks like: 1 SYS13056*256+39 AUSTROSPEED 1G GR
Plus-Comp compiler: Failed: PRG compiled and started but draw nothing on screen.
So, still only AustroSpeed could generate a useful output.
As far as I know, the other compilers do not support Plus/4 specific commands, just a 1-to-1 conversion from C64, supports only V2.0 commands.
So the Mandelbrot V3.5 cannot be compiled with other compilers.
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