PLA: Difference between revisions

Latest revision as of 17:39, 23 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Stack (Pull)	68	1 byte	4 cycles*


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

PLA (PulL Accumulator) is a 65x instruction that pulls the value at the top of the stack into the accumulator. PLA increments the stack pointer before the pull by the number of bytes pulled. If the accumulator is 16 bits wide, the low byte is pulled and then the high byte is pulled.

The Eyes & Lichty page on PLA has a typo that says the 65x pull instructions "set" the zero and negative flags; it should say "affect."

The negative flag will then match the most significant bit of the pulled value. The zero flag will indicate whether the pulled value is zero.

Syntax

PLA

Cycle Penalty

PLA takes one extra cycle if the accumulator is 16 bits wide.

External Links

Eyes & Lichty, page 483 on PLA
Labiak, page 167 on PLA
8.6 on MCS6500 Manual, page 118 on PLA
Carr, page 268 on PLA
Leventhal, page 3-83 on PLA
snes9x implementation of https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1982

@@ Line 7: / Line 7: @@
 |'''Speed'''
 |+
-|[[Stack Addressing|Stack]]
+|[[Stack Addressing|Stack]] (Pull)
 |68
 |1 byte
@@ Line 15: / Line 15: @@
 {| class="wikitable" style="float:right;clear:right;width:30%"
 !colspan="9"|Flags Affected
+|+
+|[[Negative Flag|N]]
+|[[Overflow Flag|V]]
+|[[M Flag|M]]
+|[[X Flag|X]]
+|[[Decimal Flag|D]]
+|[[I Flag|I]]
+|[[Zero Flag|Z]]
+|[[Carry Flag|C]]
 |+
 |N
-|V
-|M
-|X
-|D
-|I
-|Z
-|C
-|+
-|
 |.
 |.
@@ Line 31: / Line 31: @@
 |.
 |.
-|
+|Z
 |.
 |}
-'''PLA''' (PulL Accumulator) is a 65x instruction that pulls the value at the top of the [[stack]] into the [[accumulator]].  PLA takes one additional cycle if the accumulator is 16 bits wide.
+'''PLA''' (PulL Accumulator) is a 65x instruction that pulls the value at the top of the [[stack]] into the [[accumulator]].  PLA increments the [[stack pointer]] before the pull by the number of bytes pulled.  If the accumulator is 16 bits wide, the low byte is pulled and then the high byte is pulled.
+The Eyes & Lichty page on PLA has a typo that says the 65x pull instructions "set" the zero and negative flags; it should say "affect."
+The [[negative flag]] will then match the most significant bit of the pulled value.  The [[zero flag]] will indicate whether the pulled value is zero.
+==== Syntax ====
+<pre>
+PLA
+</pre>
+==== Cycle Penalty ====
+* PLA takes one extra cycle if the accumulator is 16 bits wide.
 === See Also ===
@@ Line 43: / Line 55: @@
 === External Links ===
-* [[Eyes & Lichty]] page on PLA: https://archive.org/details/0893037893ProgrammingThe65816/page/n509
+* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/483 page 483] on PLA
-* [[Labiak]] page on PLA: https://archive.org/details/Programming_the_65816/page/n177
+* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n177 page 167] on PLA
-* [[MCS6500 Manual]] page on PLA: https://archive.org/details/mos_microcomputers_programming_manual/page/n137
+* 8.6 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n137 page 118] on PLA
-* [[Carr]] page on PLA: https://archive.org/details/6502UsersManual/page/n281
+* [[Carr]], [https://archive.org/details/6502UsersManual/page/n281 page 268] on PLA
-* [[Leventhal]] page on PLA: https://archive.org/details/6502-assembly-language-programming/page/n132
+* [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n132 page 3-83] on PLA
 * snes9x implementation of https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1982
 [[Category:ASM]]
 [[Category:Inherited from 6502]]
+[[Category:Pull Instructions]]
+[[Category:One-byte Instructions]]