Archive for the ‘free software’ Category

Not news: Microsoft still scummy.

April 26, 2018

With a nod to boingboing and this:
https://www.jwz.org/blog/2018/04/in-case-youve-forgotten-microsoft-is-still-a-vile-garbage-fire-of-a-company/

I’m in complete agreement with the analysis here, that Microsoft’s actions here are completely in error and they have placed profit before responsibility.

On the other hand, why Eric Lundgren chose not to hand out Ubuntu* install discs does need questioning.

* In the interest of impartiality, there are other pre-built Linux distributions available which are aimed at users not techies.

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Mandelbrot plotters for BBC BASIC

December 25, 2016

These programs were born out a discussion started at college recently. I had wrote a primitive fractal plotter for the BBC Micro many years ago. Just for fun I started converting it to RISC OS BASIC, but the end program is so far removed from the original it looks like I wrote it beginning with a blank slate.

This is the version for the BBC Micro:

REM Target BBC Micro
MODE 2
xmin=-2.5:xmax=1
xwidth=xmax-xmin
ymin=-1:ymax=1
ywidth=ymax-ymin
xsize%=160:ysize%=256:REM this is the physical size of the MODE 2 screen
:
max%=1024:REM maximum iterations
:
PROCplot(0,0)
PROCplot(2,2)
PROCplot(0,2)
PROCplot(2,0)
PROCplot(1,1)
PROCplot(3,3)
PROCplot(1,3)
PROCplot(3,1)
PROCplot(1,0)
PROCplot(3,2)
PROCplot(1,2)
PROCplot(3,0)
PROCplot(0,1)
PROCplot(2,3)
PROCplot(0,3)
PROCplot(2,1)
:
REPEAT UNTIL INKEY(0)<>-1
END
:
DEFPROCplot(f%,g%)
FOR X%=0 TO (xsize%-1) STEP 4
FOR Y%=0 TO (ysize%-1) STEP 4
a=(xwidth*(X%+f%)/xsize%)+xmin
b=(ywidth*(Y%+g%)/ysize%)+ymin
PROCit(a,b,max%)
h%=7-7*LOG(IT%)/LOG(max%)
IF (ABS(e)+ABS(f))>4 GCOL0,h% ELSE GCOL 0,0
MOVE (X%+f%)*8,(Y%+g%)*4:DRAW (X%+f%)*8,(Y%+g%)*4
NEXT Y%
NEXT X%
ENDPROC
:
DEFPROCit(a,b,ITER%)
IT%=0
e=0
f=0
REPEAT
u=(e*e)-(f*f)+a
v=(2*e*f)+b
e=u
f=v
IT%=IT%+1
UNTIL IT%=ITER% OR (ABS(e)+ABS(f))>4
ENDPROC

This is a similar version for RISC OS 5.22. It may work on earlier versions.

DIM mode% 52, pal% 256*4 
$MODE=STRING$(52,CHR$0) 
$mode%=STRING$(52,CHR$0) 
PROCmode("X1680 y1050 C16M EX1 EY1 F60") 
xsize%=1680:ysize%=1050:REM physical pixels 
aspect=ysize%/xsize% 
 
REM define the centre and scale factor here 
xcentre=-1.44251 
ycentre=-0.13409 
scale=0.52707 
 
xmin=xcentre-(scale/2) 
xmax=xcentre+(scale/2) 
xwidth=xmax-xmin 
ymin=ycentre+(scale*aspect/2) 
ymax=ycentre-(scale*aspect/2) 
ywidth=ymax-ymin 
max%=8192:REM maximum iterations 
FOR X%=0 TO (xsize%-1) STEP 1 
FOR Y%=0 TO (ysize%-1) STEP 1 
a=(xwidth*X%/xsize%)+xmin 
b=(ywidth*Y%/ysize%)+ymin 
REM a is the real component of complex number c 
REM b is the imaginary component of c 
PROCit(a,b,max%) 
REM apply LOG scale 
h%=360-360*LOG(IT%)/LOG(max%) 
IF (ABS(e)+ABS(f))>4 PROCsethsv(h%,&FF,&FF) ELSE SYS"ColourTrans_SetGCOL",0,,,&100,0 
MOVE X%*2,Y%*2:DRAW X%*2,Y%*2 
NEXT Y% 
NEXT X% 
REPEAT UNTIL INKEY(0)<>-1 
END 
: 
DEFPROCit(a,b,ITER%) 
IT%=0 
e=0:REM e and f are the real, imaginary parts of z 
f=0 
REPEAT 
REM z=(z*z)+c 
REM square z, result in u,v 
u=(e*e)-(f*f) 
v=2*e*f 
REM add c, put the result in e 
e=u+a 
f=v+b 
REM count it then quit or bail 
IT%=IT%+1 
UNTIL IT%=ITER% OR (ABS(e)+ABS(f))>4 
ENDPROC 
 
DEFPROCsethsv(h%,s%,v%) 
SYS"ColourTrans_ConvertHSVToRGB",h%*&10000,s%*&100,v% TO r%,g%,b% 
SYS"ColourTrans_SetGCOL",(b%<<24)+(g%<<16)+(r%<<8),,,&100,0 
ENDPROC 
 
DEFPROCmode(mode$) 
FOR i%=1 TO LENmode$ 
MID$(mode$,i%,1)=CHR$(ASC(MID$(mode$,i%,1)) OR 32):REM force A-Z to lower case 
NEXT i% 
smode$=" "+mode$ 
IF INSTR(smode$," x")=0 THEN PRINT" x pixels missing from mode string (="""mode$""") passed to PROCmode.":ENDPROC 
IF INSTR(smode$," y")=0 THEN PRINT" y pixels missing from mode string passed to PROCmode.":ENDPROC 
IF INSTR(smode$," c")=0 AND INSTR(smode$," g")=0 THEN PRINT" colours missing from mode string passed to PROCmode.":ENDPROC 
xpix%=VALRIGHT$(smode$,LENsmode$-INSTR(smode$," x")-1) 
ypix%=VALRIGHT$(smode$,LENsmode$-INSTR(smode$," y")-1) 
col_start%=INSTR(smode$," c") 
IF col_start%=0 THEN col_start%=INSTR(smode$," g") 
colour$="":col_start%+=1:offset%=0 
REPEAT 
colour$+=MID$(smode$,col_start%+offset%,1) 
offset%+=1 
UNTIL MID$(smode$,col_start%+offset%,1)=" " OR (col_start%+offset%)>LENsmode$ 
IF INSTR("c2g2c4g4c16g16c256g256c32kc16m",colour$)=0 THEN PRINT" number of colours specified in """mode$""" is not available." 
IF INSTR(smode$," f")<>0 framerate%=VALRIGHT$(smode$,LENsmode$-INSTR(smode$," f")-1) ELSE framerate%=-1 
IF INSTR(smode$," ex")<>0 THEN ex%=VALRIGHT$(smode$,LENsmode$-INSTR(smode$," ex")-2) ELSE ex%=1 
IF INSTR(smode$," ey")<>0 THEN ey%=VALRIGHT$(smode$,LENsmode$-INSTR(smode$," ey")-2) ELSE ey%=1 
REM put together mode block now. 
pos%=0 
mode%!pos%=1:pos%+=4 
mode%!pos%=xpix%:pos%+=4 
mode%!pos%=ypix%:pos%+=4 
IF colour$="c2" OR colour$="g2" THEN 
mode%!pos%=0:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="c4" OR colour$="g4" THEN 
mode%!pos%=1:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="c16" THEN 
mode%!pos%=2:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="g16" THEN 
mode%!pos%=2:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="c256" THEN 
mode%!pos%=3:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="g256" THEN 
mode%!pos%=3:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
mode%!pos%=0:pos%+=4 
mode%!pos%=&80:pos%+=4 
mode%!pos%=3:pos%+=4 
mode%!pos%=&FF:pos%+=4 
ENDIF 
IF colour$="c32k" THEN 
mode%!pos%=4:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
IF colour$="c16m" THEN 
mode%!pos%=5:pos%+=4 
mode%!pos%=framerate%:pos%+=4 
mode%!pos%=5:pos%+=4 
mode%!pos%=ey%:pos%+=4 
mode%!pos%=4:pos%+=4 
mode%!pos%=ex%:pos%+=4 
ENDIF 
mode%!pos%=-1 
MODE mode% 
IF colour$="g256" THEN 
FOR c%=0 TO 255 
pal%!(c%*4)=FNadd(c%,c%,c%) 
NEXT 
SYS"ColourTrans_WritePalette",-1,,pal% 
ENDIF 
IF colour$="g16" THEN 
pal%!0=FNadd(&FF,&FF,&FF) 
pal%!4=FNadd(&DD,&DD,&DD) 
pal%!8=FNadd(&BB,&BB,&BB) 
pal%!12=FNadd(&99,&99,&99) 
pal%!16=FNadd(&77,&77,&77) 
pal%!20=FNadd(&55,&55,&55) 
pal%!24=FNadd(&33,&33,&33) 
pal%!28=FNadd(&00,&00,&00) 
pal%!32=FNadd(&10,&10,&10) 
pal%!36=FNadd(&C0,&C0,&C0) 
pal%!40=FNadd(&60,&60,&60) 
pal%!44=FNadd(&20,&20,&20) 
pal%!48=FNadd(&E0,&E0,&E0) 
pal%!52=FNadd(&40,&40,&40) 
pal%!56=FNadd(&A0,&A0,&A0) 
pal%!60=FNadd(&80,&80,&80) 
SYS"ColourTrans_WritePalette",-1,,pal% 
ENDIF 
ENDPROC 
: 
DEFFNadd(r%,g%,b%) 
=(b%<<24) OR (g%<<16) OR (r%<<8)

Feel free to play with them and use the code for what you wish.

This is some example output from BeebEm, using the values:

xmin=-1.49142

xmax=-1.1561

ymin=-0.07797

ymax=0.025735

max%=2048

(I have increased the maximum number of iterations, to try and prevent the image becoming ‘bitty’. This is more important as you decrease the plot window; otherwise known as zooming in)

This image was produced in about 10 hours, with BeebEm emulating a 65C02 co-processor, and with the emulator running at 100x real-time speed.

8bit_mandelbrot

Just for fun here is the same area using the RISC OS program:
29032017.png

Qalculate!

January 31, 2015

Just a note of thanks to the authors of Qalculate! because I’ve just discovered it today. My elderly Casio fx-7700GB has started to consume batteries like Smarties. With Qalculate! I can continue to do calculations with fractions so I don’t lose precision to decimals in my Circuit Theory homework.

Installing it on Ubuntu (assuming you’re using the default window manager) makes it less pink as well.