User`s manual

5-6
CHR$ may also be used to display any of the 64 graphics characters.
(See Appendix C, Graphics Codes.)
10 CLS
20 FOR I=129 TO 191
30 PRINT I;CHR$(I),
40 NEXT
50 GOT0 50
(RUN the program to see the various graphics characters.)
Codes 0-31 are display control codes. Instead of returning an actual display
character, they return a control character. When the control character is
PRINTed, the function is performed. For example, 23 is the code for 32
character-per-line format; so the command, PRINT CHR$(23) converts the
display format to 32 characters per line. (Hit CLEAR, execute CLS, or
execute PRINT CHR$(28) to return to 64 character-per-line format.)
FRE
(string)
When used with a string variable or string constant as an argument, returns
the amount of string storage space currently available. Argument must be
enclosed in parentheses. FRE causes BASIC to start searching through
memory for unused string space. If your program has done a lot of string
processing, it may take several minutes to recover all the "scratch pad" type
memory.
500 PRINT FRE(A$),FRE(L$),FRE("Z")
All return the same value.
The string used has no significance; it is a dummy variable. See Chapter 4,
CLEAR
n.