vault backup: 2022-08-01 11:20:26

content/notes/07-6809-advanced.md

@@ -10,12 +10,21 @@ tags:
 - implied `inca`
 - immediate `lda #$00`
 - extended `LDA $31FE` 
-- extended indirect `LDA [$31FE]` or `LDA [HERE]`
-	- useful in a device driver
+- extended indirect `LDA [$31FE]` or `LDA [HERE]` points to a memory location which specifies another memory location
 - direct `LDA $ff` or `lda <HERE`
 - register `trf X,Y`
-- indexed
-- indexed indirect
-- relative
-	- program counter relative
+- indexed `LDA $3111E, X` use memory location that is the sum of the operands
+	- `LDA ,X`
+	- `LDA $23,X`
+	- etc
+- indexed indirect `LDA [$10, X]`
+- relative `BEQ HERE`
+	- BEQ does a short branch
+	- LBEQ does a long branch
+	- the value is relative to HERE
+- program counter relative `LDA TABLE,PCR ; A = the value stored at TABLE`
+	- if all memory references are relative, then the program cna be loaded anywhere is memory, and will still work. It is said to be **relocatable**
+
+
+