I was about to ask a question on why I could only load a program of about 898 bytes into a 1K zx81 but after a bit of checking, found that by using 'RAND USR VAL "xxxxx"', BASIC needs about 50 bytes more to handle it then just "RAND USR xxxxx".
I can now load a maximum of 949 bytes.
The first 9 bytes are not in the .p file and the machine stack is about 16 bytes which leaves about 50 bytes still unaccounted for.
Just tried using "PRINT USR xxxxx" and can now load 953 bytes.
Loading 1K programs
Loading 1K programs
Memotech rules
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BrunoFlorindo
- Posts: 290
- Joined: Sat May 10, 2008 2:46 am
- Location: Anaheim, CA, USA
Re: Loading 1K programs
Every little bit helps. 
Thanks for the tip!
Thanks for the tip!
Re: Loading 1K programs
I thought ZX81 1K can load/run 1024 bytes.
So how is that really?
So how is that really?
IN NIHILUM REVERTERIS - a big text-adventure game for ZX81: http://tiny.pl/g2m6m
"MONOCHROME" issue 5 - (Spring 2014) free paper/PDF magazine about ZX81: http://tiny.pl/q2m44
ZX81 COMPETITIONS 2007/2009: http://zx81.republika.pl/
"MONOCHROME" issue 5 - (Spring 2014) free paper/PDF magazine about ZX81: http://tiny.pl/q2m44
ZX81 COMPETITIONS 2007/2009: http://zx81.republika.pl/
Re: Loading 1K programs
Hi again yerzmyey,
The ZX81 does have 1024 bytes but the ROM needs about 50 bytes to load a program. Once loaded those 50 bytes can be used to store data. Unfortunately the space taken up by system variables is only partially usable as the screen generating ROM code uses some of them.
The ZX81 does have 1024 bytes but the ROM needs about 50 bytes to load a program. Once loaded those 50 bytes can be used to store data. Unfortunately the space taken up by system variables is only partially usable as the screen generating ROM code uses some of them.
Memotech rules