ADC: Difference between revisions

Latest revision as of 22:38, 28 June 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Immediate	69	2 bytes	2 cycles*
Absolute	6D	3 bytes	4 cycles*
Absolute Long	6F	4 bytes	5 cycles*
Direct Page	65	2 bytes	3 cycles*
Direct Page Indirect	72	2 bytes	5 cycles*
Direct Page Indirect Long	67	2 bytes	6 cycles*
Absolute Indexed by X	7D	3 bytes	4 cycles*
Absolute Long Indexed by X	7F	4 bytes	5 cycles*
Absolute Indexed by Y	79	3 bytes	4 cycles*
Direct Page Indexed by X	75	2 bytes	4 cycles*
Direct Page Indexed Indirect by X	61	2 bytes	6 cycles*
Direct Page Indirect Indexed by Y	71	2 bytes	5 cycles*
Direct Page Indirect Long Indexed by Y	77	2 bytes	6 cycles*
Stack Relative	63	2 bytes	4 cycles*
Stack Relative Indirect Indexed by Y	73	2 bytes	7 cycles*


Flags Affected
N	V	M	X	D	I	Z	C
		.	.	.	.

ADC (Add with Carry) is 65x instruction that performs an addition. As there is no add-without-carry instruction, a CLC should be run (or the carry flag otherwise ensured to be clear) before an ADC, or else the sum will be one greater than expected.

The sum is stored in the accumulator.

After ADC runs, the carry flag will indicate whether the addition caused an unsigned overflow. The zero flag will be set if the sum is zero and cleared otherwise.

External Links

Eyes & Lichty page 423, on ADC: https://archive.org/details/0893037893ProgrammingThe65816/page/n449
Labiak page 115 on ADC: https://archive.org/details/Programming_the_65816/page/n125
MCS6500 Manual page 7 on ADC: https://archive.org/details/mos_microcomputers_programming_manual/page/n22
https://archive.org/details/mos_microcomputers_programming_manual/page/n204, lbid.
Carr page 245 on ADC: https://archive.org/details/6502UsersManual/page/n258
Leventhal page 3-38 on ADC: https://archive.org/details/6502-assembly-language-programming/page/n87
undisbeliever on ADC: https://undisbeliever.net/snesdev/65816-opcodes.html#adc-add-with-carry

@@ Line 106: / Line 106: @@
 '''ADC''' (Add with Carry) is 65x instruction that performs an addition.  As there is no add-without-carry instruction, a [[CLC]] should be run (or the carry flag otherwise ensured to be clear) before an ADC, or else the sum will be one greater than expected.
+The sum is stored in the accumulator.
+After ADC runs, the [[carry flag]] will indicate whether the addition caused an unsigned overflow.  The [[zero flag]] will be set if the sum is zero and cleared otherwise.
 === See Also ===