Disable and Enable BREAK at will.
Posted: Sun Feb 28, 2016 10:33 pm
Enable and Disable BREAK at will.
One of the most annoying things about the ZX81 is that when you BASIC program is running anytime you press the SPACE key
it will cause a BREAK your BASIC program.
I've been working on this for awhile and I've come up with a method to be able to disable or enable the BREAK key at will.
When the BREAK key is disabled you can actually read the SPACE and "£" keys with INKEY$ !!!
The method consists of copying a small portion of the ROM, and making some of POKEs.
Creating the machine code is pretty painless since most of it is just a copy of the ROM.
To use the routine.
You don't have to call the USR when changing from enabled to disabled only the POKE is needed.
However, you WILL need to call the USR again after any INPUT command.
Here is a demo program
Simple word processor demo showing ability to use SPACE key.
Press SHIFT-Q to stop.
NOTE line 30 is a SHIFT-Q inside quotes.
I have tried this on a real TS1500 and on the eightyone emulator.
Please let me know if you try this and if it works or doesn't work.
Bean
One of the most annoying things about the ZX81 is that when you BASIC program is running anytime you press the SPACE key
it will cause a BREAK your BASIC program.
I've been working on this for awhile and I've come up with a method to be able to disable or enable the BREAK key at will.
When the BREAK key is disabled you can actually read the SPACE and "£" keys with INKEY$ !!!
The method consists of copying a small portion of the ROM, and making some of POKEs.
Creating the machine code is pretty painless since most of it is just a copy of the ROM.
Code: Select all
1 REM [70 characters]
10 FOR A=1644 TO 1709
20 POKE 14870+A,PEEK A
30 NEXT A
RUN
DELETE Lines 10 thru 30
enter as direct commands
POKE 16510,0
POKE 16569,24
POKE 16580,195
POKE 16581,174
POKE 16582,6
Code: Select all
10 RAND USR 16521 ' start (use again after any INPUT command)
20 POKE 16569,24 ' to disable BREAK key
1000 POKE 16569,56 ' to enable BREAK key
However, you WILL need to call the USR again after any INPUT command.
Here is a demo program
Code: Select all
0 REM machine code from above
10 RAND USR 16521
20 POKE 16569,24
30 PRINT "BREAK KEY IS DISABLED."
40 PAUSE 120
50 FOR A=1 TO 300
60 PRINT "A";
70 NEXT A
80 POKE 16569,56
90 PRINT "BREAK KEY IS ENABLED."
100 PAUSE 120
110 FOR A=1 TO 300
120 PRINT "X";
130 NEXT A
Press SHIFT-Q to stop.
NOTE line 30 is a SHIFT-Q inside quotes.
Code: Select all
0 REM machine code from above
10 RAND USR 16521
20 LET A$=INKEY$
30 IF A$="" THEN GOTO 20
40 IF INKEY$ = """" THEN STOP
50 PRINT A$;
60 IF INKEY$<>"" THEN GOTO 60
70 GOTO 20
Please let me know if you try this and if it works or doesn't work.
Bean
