USR: Your Gateway to Machine Language Magic

Ready to tap into the raw power of your Commodore 64? Want to unlock the secrets of machine language programming? Look no further than the USR command, your gateway to a world of high-performance routines and custom hardware control. Think of it as your backstage pass to the C64's inner workings!

Syntax

USR(<numeric expression>)

Where: - <numeric expression>: A numeric value passed to the machine language routine as an argument. The type and meaning of this value depend on the specific routine.

Applications

The USR command opens up a whole new dimension of programming, allowing you to:

Boost performance: Execute time-critical code in machine language for lightning-fast speed.
Control hardware directly: Manipulate graphics, sound, and other system features at the lowest level.
Create custom routines: Implement functions not available in BASIC, like sprite collision detection or advanced math calculations.
Explore the depths of your C64: Learn how your computer works at its core and unleash its hidden potential.

How It Works

Preparation: Write your machine language routine using a tool like an assembler. Make sure it's stored in memory at a known location.
The Call: Use the USR command in your BASIC program, passing any necessary arguments.
Execution: The C64 jumps to your machine language routine, which executes its code.
Return: When the routine is finished, it returns a numeric value to your BASIC program, which can be used for further processing.

Code Example (Conceptual)

10 SYS 828 :rem Set the starting address for your ML routine (replace with actual address)
20 X = 10
30 R = USR(X)  :rem Call your ML routine with X as the argument
40 PRINT R    :rem Print the value returned by the routine

(Note: This is a simplified example. Writing and integrating machine language routines requires knowledge of assembly language and memory management.)

USR in the Wild: The Demo Scene Wizard

Imagine you're part of the C64 demo scene, creating stunning audiovisual presentations. With USR, you could write machine language routines to push the C64's graphics and sound capabilities to their limits, crafting mesmerizing demos that leave your audience in awe.

Don't be afraid to venture beyond BASIC! With USR, you can tap into the raw power of machine language programming and elevate your Commodore 64 projects to new heights. It's a challenging but rewarding path that opens up a world of possibilities for customization and performance. So gather your courage, dive into the depths of machine code, and unleash the full potential of your C64!

ABS (Function) AND (Operator) ASC (Function) ATN (Function) CHR$ (Function) CLOSE (Command) CLR (Command) CMD (Command) CONT (Command) COS (Function) DATA (Command) DEF (Command) DIM (Command) END (Command) EXP (Function) FN (Function) FOR (Command) FRE (Function) GET (Command) GET# (Command) GOSUB (Command) GOTO (Command) IF (Command) INPUT (Command) INPUT# (Commands) INT (Function) LEFT$ (Function) LEN (Function) LET (Command) LIST (Command) LOAD (Command) LOG (Function) MID$ (Function) NEW (Command) NEXT (Command) NOT (Function) ON (Command) OPEN (Command) OR (Operator) PEEK (Function) POKE (Command) POS (Command) PRINT (Command) PRINT# (Command) READ (Command) REM (Command) RESTORE (Command) RETURN (Command) RIGHT$ (Function) RND (Function) RUN (Command) SAVE (Command) SGN (Function) SIN (Function) SPC (Function) SQR (Function) STATUS (System Variable) STEP (Command) STOP (Command) STR$ (Function) SYS (Command) TAB (Function) TAN (Function) THEN (Command) TIME (System Variable) TIME$ (System Variable) TO (Command) USR (Function) VAL (Function) VERIFY (Command) WAIT (Command)