DEY: Difference between revisions

Latest revision as of 20:09, 12 August 2024


Basic Info
Addressing Mode	Opcode	Length	Speed
Implied (type 1)	88	1 byte	2 cycles


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

DEY is a 65x instruction that decrements the Y index register by one. DEY ignores the decimal flag. Unlike SBC, DEY never affects the carry flag.

Syntax

DEY

External Links

Eyes & Lichty, page 453 on DEY
Labiak, page 140 on DEY
7.7 on MCS6500 Manual, page 98 on DEY
Carr, page 258 on DEY
Leventhal, page 3-62 on DEY
snes9x implementation of DEY: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1514
Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.1.1.3

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-{| class="wikitable" style="float:right;clear:right;width:30%"
+{| class="wikitable" style="float:right;clear:right;width:40%"
 !colspan="8"|Basic Info
 |+
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 |'''Speed'''
 |+
-|implied
+|[[Implied]] (type 1)
 |88
 |1 byte
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 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="8"|Flags Clobbered
+!colspan="8"|Flags Affected
+|+
+|[[N Flag|N]]
+|[[V Flag|V]]
+|[[M Flag|M]]
+|[[X Flag|X]]
+|[[D Flag|D]]
+|[[I Flag|I]]
+|[[Z Flag|Z]]
+|[[C Flag|C]]
 |+
 |N
-|V
-|M
-|X
-|D
-|I
-|Z
-|C
-|+
-|
 |.
 |.
@@ Line 31: / Line 31: @@
 |.
 |.
-|
+|Z
 |.
 |}
-'''DEY''' is a 65x instruction that decrements the [[Y index register]] by one.
+'''DEY''' is a 65x instruction that decrements the [[Y index register]] by one.  DEY ignores the [[decimal flag]].  Unlike [[SBC]], DEY never affects the [[carry flag]].
+==== Syntax ====
+<pre>
+DEY
+</pre>
 === See Also ===
+* [[DEC]]
 * [[DEX]]
 * [[INX]]
 * [[INY]]
+* [[DEC (SPC700)]]
+* [[DEC (Super FX)]]
 === External Links ===
-* [[Eyes & Lichty]] page on DEY: https://archive.org/details/0893037893ProgrammingThe65816/page/n479
+* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/453 page 453] on DEY
-* [[Labiak]] page on DEY: https://archive.org/details/Programming_the_65816/page/n149
+* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n150 page 140] on DEY
-* [[MCS6500 Manual]] page on DEY: https://archive.org/details/mos_microcomputers_programming_manual/page/n116
+* 7.7 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n116 page 98] on DEY
-* [[Carr]] page on DEY: https://archive.org/details/6502UsersManual/page/n271
+* [[Carr]], [https://archive.org/details/6502UsersManual/page/n271 page 258] on DEY
-* [[Leventhal]] page on DEY: https://archive.org/details/6502-assembly-language-programming/page/n111
+* [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n111 page 3-62] on DEY
 * snes9x implementation of DEY: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1514
+* Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.1.1.3
 [[Category:ASM]]
 [[Category:Inherited from 6502]]
+[[Category:One-byte Instructions]]
+[[Category:Implied Instructions]]
+[[Category:Two-cycle Instructions]]