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How to make listing visable after pokes in line 1
Posted: Wed Jun 12, 2024 2:52 pm
by RS232
I thought i would raise this, as this has long been a frustration. Anyone found a good solution or a memory location you do not have to "clear" for?
It got me thinking. Could it just be you need to poke readable characters instead of leaving a non printable character at the end and start of a REM ?
Thanks in advance
Re: How to make listing visable after pokes in line 1
Posted: Wed Jun 12, 2024 3:20 pm
by 1024MAK
Erm, what about
Assuming your program is long enough such that you can select a line later in the program, LIST <line number> at this later line, then earlier lines will not be listed.
It is possible to move RAMTOP by poking a new value in. The trouble is you then have to do a NEW for the system to take notice. The RAM between RAMTOP and the actual end of working RAM is then free for machine code or data. The snag being that this area is not saved or loaded by the standard SAVE and LOAD commands.
Mark
Re: How to make listing visable after pokes in line 1
Posted: Wed Jun 12, 2024 7:28 pm
by RS232
I didn't explain well enough , the problem is that line 1, makes all my listing disapear unless i list lines direct.
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 3:03 am
by XavSnap
Hi,
You typed a listing with a 1 REM XXX, and the LIST command can't display the other lines...
I thinks you entered the bad REM length, and the BASIC point to the bad "NEXT LINE" memory offset !
The REM line length is located at 16511/16512.
The "End Line Tag" at 16514+LENGTH -2 bytes.(The "REM" token ($EA) & the End of line ($76)!)
If the LENGTH point to another memory offset, the ROM will crash or ignore the next lines.
PRINT PEEK (16512+( PEEK 16512*256+PEEK 16511))
MUST be 128 , the End Of Line memory offset!
Next_Line = PRINT PEEK (16513+( PEEK 16512*256+PEEK 16511))
If not, you had to peek all around memory values, and set the right length
You can hide the REM using POKE 16514,118 & POKE 16515,118...
To add a "End of line"+"End of BASIC" Listing.
But a LIST 2 will display the next lines... As Mark said.
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 7:57 am
by mrtinb
RS232 wrote: ↑Wed Jun 12, 2024 7:28 pm
I didn't explain well enough , the problem is that line 1, makes all my listing disapear unless i list lines direct.
Well that's one of the quirks of ZX81. You could make a machine code program that avoids bytes in the range $70 - $7F.
You could also store your machine code as a variable.
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 8:15 am
by XavSnap
Thanks Spock !
I'm Hikaru Sulu & Mark is Pavel Chekov...
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 8:40 am
by Paul
Isn't mark McCoy? He gives so many healing tips
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 10:34 am
by RS232
Awesome reply. Thank you!
XavSnap wrote: ↑Thu Jun 13, 2024 3:03 am
Hi,
You typed a listing with a 1 REM XXX, and the LIST command can't display the other lines...
I thinks you entered the bad REM length, and the BASIC point to the bad "NEXT LINE" memory offset !
REM_Struc.JPG
The REM line length is located at 16511/16512.
The "End Line Tag" at 16514+LENGTH -2 bytes.(The "REM" token ($EA) & the End of line ($76)!)
If the LENGTH point to another memory offset, the ROM will crash or ignore the next lines.
PRINT PEEK (16512+( PEEK 16512*256+PEEK 16511))
MUST be 128 , the End Of Line memory offset!
Next_Line = PRINT PEEK (16513+( PEEK 16512*256+PEEK 16511))
If not, you had to peek all around memory values, and set the right length
You can hide the REM using POKE 16514,118 & POKE 16515,118...
To add a "End of line"+"End of BASIC" Listing.
But a LIST 2 will display the next lines... As Mark said.
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 10:35 am
by RS232
Thanks.
mrtinb wrote: ↑Thu Jun 13, 2024 7:57 am
RS232 wrote: ↑Wed Jun 12, 2024 7:28 pm
I didn't explain well enough , the problem is that line 1, makes all my listing disapear unless i list lines direct.
Well that's one of the quirks of ZX81. You could make a machine code program that avoids bytes in the range $70 - $7F.
You could also store your machine code as a variable.
Re: How to make listing visable after pokes in line 1
Posted: Thu Jun 13, 2024 10:16 pm
by GCHarder
You could try something like this...
10 POKE 16419,10
This sets the automatic line listing to 10, now LIST should start at 10, I think.
Maybe not what your asking though.
Greg