Sinclair ZX80 / ZX81 / Z88 Forums

Posted: **Tue May 04, 2021 4:07 am**

Hi,

A little routine to repeat a character code and preserve some memory room.

Example:

10 PRINT "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
20 PRINT 
30 PRINT "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"

Take more memory room than…

Code: Select all

10 PRINT USR X;"X"
20 PRINT 
30 PRINT USR X;"X"

My code:

Code: Select all

.org 16514

	LD HL,($4016)
	INC HL
	INC HL
	LD B,$20
	LD C,$00
	LD A,(HL)
Loop:
	RST 10H
	DJNZ Loop
	INC HL
	INC HL
	LD ($4016),HL
	JP $005B
.end

Code: Select all

     1  REM [HEX:\
2A,16,40,23,23,06,20,0E,\
00,7E,D7,10,FD,23,23,22,\
16,40,C3,5B,00 ]
2 LET X=VAL "16514"
3 PRINT AT 10,0;
4 PRINT USR X;"\,,"
5 PRINT TAB 14;"HELLO",
6 PRINT USR X;"\''"

LINE.P: (1.01 KiB) Downloaded 133 times

Note:
-Affect the cursor location.

-Can't be use with RAND USR, it will be compiled with any TexttoP, but the line can't be edited with the basic editor.

-All values and characters after this ASM call are ignored !

- if the "C3,5B,00 " (JP $005B) is replaced by "C9" (Ret) can't be use… the PRINT command will display the BC value !
In this case, just use the TAB function, if the line start at the first row…

Example: (The RET value in always BC=0)

Code: Select all

     1  REM [HEX:\
2A,16,40,23,23,06,20,0E,\
00,7E,D7,10,FD,23,23,22,\
16,40,C9 ]
2 LET X=VAL "16514"
3 PRINT AT 10,0;
4 PRINT TAB USR X;"\,,";TAB 14;"HELLO",TAB USR X;"\''"

LINE2.P: (1021 Bytes) Downloaded 131 times

Have fun...

Posted: **Tue May 04, 2021 4:47 am**

Another way to preserve memory, is to set a variable …

Code: Select all

10 LET P$="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
20 PRINT P$,,P$

But, this code keep a value in the Vars buffer, and is needed if it's use more than 3 times !
And use more memory if the repeat character code if different…

Code: Select all

10 LET P$="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" (also mirrored in the Var memory room, take 64 bytes!)
10 LET Q$="ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ" (also mirrored in the Var memory room, take 64 bytes!)
20 PRINT P$,,Z$,,P$,,Z$

Sinclair ZX80 / ZX81 / Z88 Forums

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