Code: Select all
10 FOR I% = 1 TO 255
20 S$ = S$ + "X"
30 T$ = T$ + "X"
40 NEXT
50 DIM P% -1
60 PRINT P% - LOMEM
RichardRussell wrote: ↑Wed 04 Nov 2020, 10:11Make of that what you will.
- BASIC 2 (BeebEm): 7764 bytes
- BASIC 5 (RedSquirrel): 16664 bytes
- Matrix Brandy 1.22.8: 12792 bytes
- BBC BASIC for SDL 2.0: 1160 bytes
That must be the small-memory-model (64K) version. With the 640K version I get:
I'm not sure whether waking up a 4-year-old thread is appropriate, but I wanted to add the result from BBC BASIC (Z80) version 5.00 which didn't exist then. The total (heap) memory usage from alternately lengthening two strings, one byte at a time, to 255 bytes each (a 'pathological case' for BBC BASIC) is:RichardRussell wrote: ↑Wed 04 Nov 2020, 10:11 The program prints the total heap usage; here is what I got for the different versions:
The Matrix Brandy value got worse in the later version!ARM BASIC 5 (RedSquirrel): 16664 bytes
Matrix Brandy v1.23.4 (Windows): 12864 bytes
BBC BASIC for Windows v1.07f: 8470 bytes
Code: Select all
10 S% = RND(-1234)
20 DIM A% -1
30 FOR I% = 1 TO 1000
40 A$ = STRING$(RND(255), "A")
50 B$ = STRING$(RND(255), "B")
60 NEXT I%
70 DIM B% -1
80 PRINT "Total memory used = "; B%-A%; " bytes"
It does look like it, but other factors could be at play because I no longer have the earlier version installed here to compare with. For example it's quite possible that four years ago I was running the 32-bit version of Matrix Brandy and now I'm running the 64-bit version. So I wouldn't read too much into it, especially as the difference is tiny as a proportion.
I should point out that although the program seeds the random number generator (so it always gives the same result on any given platform) the values returned by RND(255) won't be identical on different versions of BBC BASIC. So I'm not actually comparing 'like with like', although looping over 1000 iterations should reduce the consequences of this.Richard Russell wrote: ↑Sat 21 Dec 2024, 12:11 There's less variation than with the 'pathological' case, but ARM BASIC 5 and Matrix Brandy stand out as using a surprising amount of memory compared with the rest.
When you consider that two 255-character strings will require 510 bytes of storage, plus the memory required to hold the variable references themselves, the fact that the majority of BBC BASIC versions only use a total of a Kilobyte or so of heap when running this program really isn't too bad at all, considering there is no traditional 'garbage collection'.Richard Russell wrote: ↑Sat 21 Dec 2024, 12:11 There's less variation than with the 'pathological' case, but ARM BASIC 5 and Matrix Brandy stand out as using a surprising amount of memory compared with the rest.
Code: Select all
10 S% = RND(-1234)
20 DIM A% -1
22 A$ = STRING$(255, "A")
24 B$ = STRING$(255, "B")
30 FOR I% = 1 TO 1000
40 A$ = STRING$(RND AND 255, "A")
50 B$ = STRING$(RND AND 255, "B")
60 NEXT I%
70 DIM B% -1
80 PRINT "Total memory used = "; B%-A%; " bytes"