Posted By
JamesC
on 2017-11-27
20:57:42
|  Re: Patch for BASIC to make it faster?
SVS noted a few months ago that BASIC banks in RAM even when the needed byte(s) are below $8000:
forum/34019
Just for grins and giggles, I wondered how much speed we might gain by shrinking the screen from 40x25 to 38x24 (assuming that the CPU would go to 2x speed slightly more per video frame).
It turns out that we don't gain a thing by this. 
PAL (using YAPE 1.1.5, 100% speed 50fps):
Normal screen: 8371 jiffies to count from 0 to 100,000
Reduced screen: 8371 jiffies
Screen blanked: 5578 jiffies
NTSC (100% speed 60fps):
Normal screen: 9229 jiffies
Reduced screen: 9229 jiffies
Screen blanked: 5552 jiffies
5 PRINT"COUNTING..."
10 TI$="000000":FOR X= 0 TO 100000:NEXT
20 A = TI
30 PRINT CHR$(27)"R"
40 POKE65286,PEEK(65286)AND247
41 POKE65287,PEEK(65287)AND247
45 PRINT"COUNTING AGAIN..."
50 TI$="000000":FOR X= 0 TO 100000:NEXT
60 B = TI
70 POKE65286,PEEK(65286)OR8
71 POKE65287,PEEK(65287)OR8
80 PRINTCHR$(27)"N"
90 P=PEEK(65286):POKE65286,0
100 TI$="000000":FOR X= 0 TO 100000:NEXT
110 C=TI
120 POKE65286,P
130 PRINT"FULL SCREEN:";A :PRINT"REDUCED SCREEN:";B :PRINT"SCREEN OFF:";C
Kichy, how much speed might we gain if the garbage collection routine mimics how it's done on the C64?
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