Runtime evaluation: Difference between revisions

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 =={{header|6502 Assembly}}==
 The 6502 can execute code at runtime through the use of self-modifying code, provided that the code runs in RAM. For programs that are defined in ROM, the code can be copied to RAM and executed from RAM. If you have a way to type numeric values into your program and save them in a contiguous section of memory, and those values are stored as numbers and not ASCII, a <code>JMP</code> to their storage location can be used to execute arbitrary code.
+This example runs on the Commodore 64 and prints the letter A using a crude "eval":
+<lang 6502asm>;Init Routine
+*=$0801
+	db $0E,$08,$0A,$00,$9E,$20,$28,$32,$30,$36,$34,$29,$00,$00,$00
+*=$0810	;Start at $0810
+	LDA #$A9		;opcode for LDA immediate
+	STA smc_test
+	LDA #'A'
+	STA smc_test+1
+	lda #$20		;opcode for JSR
+	STA smc_test+2
+	lda #<CHROUT
+	STA smc_test+3
+	lda #>CHROUT
+	STA smc_test+4
+smc_test:
+	nop				;gets overwritten with LDA
+	nop				;gets overwritten with #$41
+	nop				;gets overwritten with JSR
+	nop				;gets overwritten with <CHROUT
+	nop				;gets overwritten with >CHROUT
+	rts				;return to basic</lang>
+{{out}}
+<pre>
+LOAD"*",8,1
+SEARCHING FOR *
+LOADING
+READY.
+RUN
+A
+READY.
+</pre>
 =={{header|ALGOL 68}}==