ASL

Basic Info
Addressing Mode	Opcode	Length	Speed
Accumulator	0A	1 byte	2 cycles
Absolute	0E	3 bytes	6 cycles*
Direct Page	06	2 bytes	5 cycles*
Absolute Indexed by X	1E	3 bytes	7 cycles*
Direct Page Indexed by X	16	2 bytes	6 cycles*

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

ASL (Arithmetic Shift Left) is a 65x instruction that shifts a value by left one bit (multiplication by two). The most significant bit is shifted into the carry flag. The least significant bit becomes a zero.

Syntax

ASL
ASL A
ASL addr
ASL dp
ASL addr, X
ASL dp, X

Cycle Penalties

• Except in accumulator addressing, ASL takes two extra cycles when the accumulator is 16 bits wide
• In direct page addressing modes, ASL takes another extra cycle if the low byte of the direct page register is nonzero.

See Also

• LSR
• ASL (SPC700)
• ROL

External Links

• Eyes & Lichty page 427, on ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/427
• lbid page 190, before & after diagram of ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n216
• Labiak page 117 on ASL: https://archive.org/details/Programming_the_65816/page/n127
• MCS6500 Manual page 149 on ASL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170
• https://archive.org/details/mos_microcomputers_programming_manual/page/n205
• Carr page 247 on ASL: https://archive.org/details/6502UsersManual/page/n260
• Leventhal page 3-41 on ASL: https://archive.org/details/6502-assembly-language-programming/page/n90
• undisbeliever on ASL: https://undisbeliever.net/snesdev/65816-opcodes.html#asl-arithmetic-shift-left