Apple-2-SW/bitmap-editor
1
0
Fork 0
mirror of https://github.com/tilleul/apple2.git synced 2025-07-18 12:24:08 +00:00
Code Issues Projects Releases Wiki Activity

Update SCRN_PLOT_your_sound_routine.md

Browse Source
This commit is contained in:
tilleul
2020-04-16 19:54:09 +02:00
committed by GitHub
parent 6ac509f842
commit ec5ebbf5d5
1 changed files with 6 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
2liners/the art of 2-liners/SCRN_PLOT_your_sound_routine.md
View File

@@ -90,7 +90,7 @@ A6 07 A4 06 AD 30 C0 88 D0 FD CA D0 F5 60
``` ```
This is only 28 characters if we omit spaces but 41 if we count spaces. This is only 28 characters if we omit spaces but 41 if we count spaces.
## PRINT code ? ## PRINT a 6502 subroutine
Since ASCII is the shortest as it takes only 14 bytes, could we use ``PRINT`` to print the code in TEXT page 1 ? Since ASCII is the shortest as it takes only 14 bytes, could we use ``PRINT`` to print the code in TEXT page 1 ?
If this code was in $400 (TEXT page 1), it would display like this: If this code was in $400 (TEXT page 1), it would display like this:
@@ -203,18 +203,20 @@ Starting with our coded ``A$`` string, instead of using ``MID$`` and ``ASC`` to
``` ```
(again the second line 1 is an optimization of the first). (again the second line 1 is an optimization of the first).
Explanation: Explanation:
The Applesoft code begins in $800 (2048). The first letter of A$ is in position $809 (2057). We simply read those values directly from the code location. The Applesoft code begins in $800 (2048). The first letter afte ``A$="`` is in location $809 (2057) in memory. We simply read those values directly from there.
All in all, it's still 105 characters long ! All in all, it's still 105 characters long !
There are variations to this technique: instead of having an assignment to a variable we could have a ``DATA``or a ``REM`` and access its precise memory location in the code. ``DATA`` is in fact shorter of 1 character (because you don't need quotes. ``REM``has the inconvenient of having to be used as the last statement of the line There are variations to this technique: instead of having an assignment to a variable we could have a ``DATA``or a ``REM`` and access its precise memory location in the code. ``DATA`` is in fact shorter of 1 character (because you don't need quotes. ``REM``has the inconvenient of having to be used as the last statement of the line.
Anyway none of these variations are short enough.
Can we do better ? Of course. Can we do better ? Of course.
## New technique: PRINT/PLOT hexadecimal ## New technique: PRINT/PLOT hexadecimal
So here comes the technique I've developed for this particular case. So here comes the technique I've developed for this particular case.
Notice that it can be used for all kinds of subroutines .... just be aware that we're "printing" routines and that the TEXT page lines are not sequential (line 1 is not in $400+40 chars) Notice that it can be used for all kinds of subroutines .... just be aware that we're "printing" routines and that the TEXT page lines are not sequential (line 1 is not in $400+40 chars). It works with any value from 0 to 255 and it's almost as easy as to type the actual hexadecimal values in the monitor.
This new (?) technique involves using four very simple instructions: PRINT, SCRN, COLOR and PLOT. This new (?) technique involves using four very simple instructions: PRINT, SCRN, COLOR and PLOT.