Defence-Force: Oric Coding Appendix 2 - 6502/65816... https://www.defence-force.org/computing/oric/coding...

Ok, I've ripped this html page on the web. I hope that anybody will annoy me for
that, but I think it's a really great summary of what you can learn of 6502
compatible chips.
I hope that mister Tabke will be ok !
By the way, anyone want to do an Oric with a 65816 CPU inside ? Could be cool,
since this processor can emulate 6502 code.
At the end, you have a complete 6502/65C02/65816 opcode list, with compatiblity
notes and timings.
Have fun reading this !

A 6502 Programmer's Introduction to the 65816

by Brett Tabke

After programming in 6502 language for over a decade, I was getting a bit
BORED. One can only code the same routines with the same opcodes so many
times before the nausea of repetition becomes overpowering. When I heard the
news that CMD was building a cartridge based on a 20 MHz 65816 I was
overjoyed. For years I've heard those with 65816 bases systems brag about its
capabilities. To us old 6502 programmers, the opportunity to program the fabled
65816 is a new lease on life.

The 65816 is an 8-/16-bit register selectable upgrade to the 6502 series

processor. With 24 bit addressing of up to 16 Megabytes of RAM, the powerful
65816 is a logical upgrade that leaves 6502 programmers feeling right at home. It
is amazing how fast one can adapt to the new processor. It sounds funny to say it,
but the only difficulty I have had learning the 65816 is that there are so many
options and choices to complete the same task, that it is hard to decide which
method is best.

To get started programming the 65816, I would recommend purchasing the book,
"Programming the 65816" from The Western Design Center, manufacturer of the
65816. While it is a bit pricey, the sheer quality and content of the 600 page book
is worth the money. Rarely, if ever, has there been a CPU manual as thorough and
detailed as the Western Design book. If you know 6502 assembly, then
Programming the 65816 is probably the only 65816 book you will ever need.

Getting a Feel for the Modes

The 65816 may be operated in Native mode or 6502 Emulation mode. Emulation
mode is a 100% 6502 compatible mode where the whole processor looks and feels
like a vintage 6502. Native mode offers 8- or 16-bit user registers and full access
to 24-bit addressing.

While in emulation mode, not only are all the 6502 opcodes present in their virgin

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form, but the new 65816 instructions are also available for usage. In fact, the first
lesson to learn about programming the 65816 is that emulation mode is much
more powerful than a stock 6502. The only true difference between emulation
mode and our venerable C64's 6510 processor is that unimplemented opcodes will
not produce the results expected on the former. Since all 256 of the potential
opcodes are now implemented on the 65816, older C64 software that uses
previously unimplemented opcodes will produce erratic results.

To select between emulation and native modes, a new phantom hidden emulation
bit (E) was added to the status register. Shown in programming models hanging
on top of the Carry bit, the emulation bit is only accessible by one instruction. The
new instruction (XCE) exchanges the status of the Carry bit and Emulation bit. To
move to emulation mode, set the carry and issue an XCE instruction. To move to
native mode, clear the carry and issue the XCE instruction.

My, How Your Index Registers Have Grown!

While in native mode there are two new directly accessible bits present in the
status register. The 65816 implements new hardware interrupt vectors which
include a new hardware BRK vector in ROM; therefore, the old BRK bit of the
status register is no longer needed. The BRK bit is replaced with the X bit to select
either 8- or 16-bit index registers. The former empty bit 5 is now filled with the M
bit to specify the accumulator and memory access as 8- or 16-bit.

Two new instructions are used to clear or set bits within the status register. The
SEP instruction sets bits, and REP clears bits. SEP and REP use a one byte
immediate addressing mode operand to specify which bits are to be set or cleared.
For example, to set the X bit for 8 bit user registers:

SEP #%00010000 ; set bit 4 for 8-bit index

; registers.

Or to clear bit 4:
REP #%00010000 ; clear bit 4 for 16-bit index
; registers.

When in 8 bit mode, the index registers perform their function in standard 6502
form. When status bit X is set to 0, both the X and Y index registers become 16
bits wide. With a 16-bit index register you can now reach out to a full 64K with the
various indexed addressing modes. An absolute load to an index register in 16-bit
mode will retrieve 2 bytes of memory-the one at the effective address and the one
at the effective address plus one. Simple things like INX or DEY work on a full 16
bit, which means you no longer have to specify a memory location for various
counters, and loops based on index counters can now be coded in a more efficient
manner.

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The formerly empty status register bit 5 is now referred to as bit M. M is used to
specify an 8- or 16-bit wide acculmulator and memory accesses. When in 8 bit
mode, (M=1), the high order 8 bits are still accessible by exchanging the low and
high bytes with a XBA instruction-it is like having two acculmulators! However;
when set for a full 16-bit wide accumulator, all math and accumulator oriented
logical intructions operate on all 16 bits! If you add up the clock cycles and bytes
required to perform a standard two byte addition, you can start to see the true
power of 16-bit registers.

More Register Improvements

Zero Page has now been renamed to Direct Page-corporate thinking, go figure. A
new processor register D was added to allow Direct Page to be moved anywhere
within the first 64K of memory. The direct page register is 16 bits wide, so you can
now specify the start of direct page at any byte. Several old instructions now
include direct page addressing as well. To move direct page, just push the new
value onto the stack (16 bits) and then PLD to pull it into the direct page register.
You may also transfer the value from the 16-bit accumulator to the direct page
register with the TCD instruction. Direct page may also be moved while in
emulation mode.

While in native mode, the stack pointer is a full 16 bits wide, which means the
stack is no longer limited to just 256 bytes. It can be moved anywhere within the
first 64K of memory (although while in emulation mode, the stack is located at
page one). There are several new addressing modes that can use the stack pointer
as a quasi-index register to access memory. Numerous new push and pull
instructions allow you to manipulate the stack. A few of the more useful stack
intructions useful to programmers, are the new instructions to push & pull index
registers with PHX/PHY and PLX/PLY.

Two other new processors registers are the Program Bank Register (PBR) and the
Data Bank Register (DBR). The Program Bank Register can be thought of as
extending the program counter out to 24 bits. Although you can JSR and JMP to
routines located in other RAM banks, individual routines on the 65816 still must
run within a single bank of 64K-there's no automatic rollover from one bank of
RAM to the next when executing successive instructions. In this sense, it may help
to think of the 65816 processor as a marriage of Commodore's C128 Memory
Management Unit (MMU) and an 'enhanced' 6502-a very similar concept.

The Data Bank Register is used to reach out to any address within the 16
megabyte address space of the 65816. When any of the addressing modes that
specify a 16-bit address are used, the Data Bank byte is appended to the
instruction address. This allows access to all 16 megabytes without having to
resort to 24-bit addressing instruction, and helps enable code that can operate
from any bank.

New Addressing Modes

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There are new addressing modes on the 65816. Several new instructions are
designed to help relocatable code that can execute at any address. The use of
relocatable code on the 6502 was extremely limited. With 16 megabytes of
address space, writing relocatable code increases the overall utility of the
program. To write relocatable code, several new instructions use Program Counter
Relative Long addressing. This allows relative branching within a 64K bank of RAM.
There's also Stack Relative addressing, and a push instruction to place the
program counter onto the stack, so that a code fragment can pull it back off and
can instantly know its execution address.

Another new feature are two Block Move instructions, one for forward MVP and
one for backward MVN. Simply load the 16-bit X register with the starting address,
the Y index register with the ending address, the accumulator with the number of
bytes to move, and issue the MVP or MVN instructions. MVN is for move negative,
and MVP is for move positive, so that your moves don't overwrite themselves.
Block Moves use two operand bytes: one for the source bank of 64K and one for
the destination bank. Memory is moved at the rate of seven clock cycles per byte.

Several new addressing modes are used to access the full address space. A 65816
assembler would decode "long" addressing given this input:

LDA $0445F2 ; load byte from $45F2 of RAM

; bank 4
LDA $03412F,x ; load byte from $412F of bank 3
; plus x.

Quite a few instructions have been given new addressing modes. How many times
have you wanted to do this:
LDA ($12) ; load indirect without an
; offset.

Or how about a table of routine addresses:

JSR ($1234,x) ; jump to a subroutine via
; indexed indirect addressing!

Other fun new instructions:

TXY,TYX Transfer directly between index registers
BRA Branch always regardless of status bits
TSB Test and set any bit of a byte
TRB Test and reset (clear) any bit of a byte
INC A/DEC A Increment or decrement the accumulator directly
STZ Store a zero to any byte

Summing Up

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As you can see, the 65816 opens up a whole new world of programming-it feels
like a new lease on life. Of course, it's going to take some time to learn the new
processor. But while the 20 MHz speed is a nice perk, I believe that the real power
of CMD's new peripheral is indeed the engine under its hood: the 65816-a super
CPU!

Native Mode Options

While in Native Mode, the m flag controls the size of Accumulator A and most Memory Operations, while the x flag controls the size
of the X and Y Index Registers. This provides 4 different configuration possibilities, as charted below. The REP and SEP instructions
are used in combination to swith configurations.
m x A/M X/Y Instructions
0 0 15-bit 16-bit REP #$30
0 1 16-bit 8-bit REP #$20
SEP #$10
1 0 8-bit 16-bit REP #$10
SEP #$20
1 1 8-bit 8-bit SEP #$30

It is important to note that the m flag will control the size of all operations dealing with memory except in operations involving the X
and Y Index Registers (CPX, CPY, LDX, LDY, STX and STY) when the x flag controls the size.

Emulation Notes
While in Emulation Mode, Accumulator A is forced to 8-bit mode. You can, however, access the upper 8 bits with instructions that
specify Accumulator B, and all 16 bits at once with instructions that specify Accumulator C. The X and Y Index Registers are also
forced to 8-bit mode, with no means available to access the upper 8 bits. To further assist in compatibility, the Stack is forced to
Page 1 of Bank 0. The Direct page Register (D) is fully functional in this mode, allowing direct page to be placed anywhere in Bank
0. Likewise, the Program Bank Register (PBR) and Data Bank Register (DBR) are also fully functional. While it would seem that
these latter items would allow programs to operate from any bank in Emulation mode, there are some caveats; interrups will force
the program bank to zero without saving the PBR first, and RTI won't attempt to restore the bank. Therefore, Native mode would be
recommended to execute programs in other banks.

Guide to 6502/65C02/65816 Instructions

|a||b||c||d||e||i||j||l||m||n||o||p||r||s||t||w||x|

Assembler
HEX Addressing Mode 02 C02 816 Bytes Cycles
Example
ADC Add With Carry [Flags affected: n,v,z,c]
ADC (dp,X) 61 DP Indexed Indirect,X x x x 2 61,2,4
ADC sr,S 63 Stack Relative x 2 41,4
ADC dp 65 Direct Page x x x 2 31,2,4
ADC [dp] 67 DP Indirect Long x 2 61,2,4
ADC #const 69 Immediate x x x 217 21,4
ADC addr 6D Absolute x x x 3 41,4
ADC long 6F Absolute Long x 4 51,4
ADC ( dp),Y 71 DP Indirect Indexed, Y x x x 2 51,2,3,4
ADC (dp) 72 DP Indirect x x 2 51,2,4
ADC (sr,S),Y 73 SR Indirect Indexed,Y x 2 71,4
ADC dp,X 75 DP Indexed,X x x x 2 41,2,4

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DP Indirect Long Indexed,

ADC [dp],Y 77 x 2 61,2,4
Y
ADC addr,Y 79 Absolute Indexed,Y x x x 3 41,3,4
ADC addr,X 7D Absolute Indexed,X x x x 3 41,3,4
ADC long,X 7F Absolute Long Indexed,X x 4 51,4
AND AND Accumulator With Memory [Flags affected: n,z]
AND (dp,X) 21 DP Indexed Indirect,X x x x 2 61,2
AND sr,S 23 Stack Relative x 2 41
AND dp 25 Direct Page x x x 2 31,2
AND [dp] 27 DP Indirect Long x 2 61,2
AND #const 29 Immediate x x x 217 21
AND addr 2D Absolute x x x 3 41
AND long 2F Absolute Long x 4 51
AND (dp),Y 31 DP Indirect Indexed, Y x x x 2 51,2,3
AND (dp) 32 DP Indirect x x 2 51,2
AND (sr,S),Y 33 SR Indirect Indexed,Y x 2 71
AND dp,X 35 DP Indexed,X x x x 2 41,2
DP Indirect Long Indexed,
AND [dp],Y 37 x 2 61,2
Y
AND addr,Y 39 Absolute Indexed,Y x x x 3 41,3
AND addr,X 3D Absolute Indexed,X x x x 3 41,3
AND long,X 3F Absolute Long Indexed,X x 4 51
ASL Accumulator or Memory Shift Left [Flags affected: n,z,c]
ASL dp 06 Direct Page x x x 2 52,5
ASL A 0A Accumulator x x x 1 2
ASL addr 0E Absolute x x x 3 65
ASL dp,X 16 DP Indexed,X x x x 2 62,5
ASL addr,X 1E Absolute Indexed,X x x x 3 75,6
BCC Branch if Carry Clear [Flags affected: none][Alias: BLT]
BCC nearlabel 90 Program Counter Relative x x x 2 27,8
BCS Branch if Carry Set [Flags affected: none][Alias: BGE]
BCS nearlabel B0 Program Counter Relative x x x 2 27,8
BEQ Branch if Equal [Flags affected: none]
BEQ nearlabel F0 Program Counter Relative x x x 2 27,8
BIT Test Bits [Flags affected: z (immediate mode) n,v,z (non-immediate modes)]
BIT dp 24 Direct Page x x x 2 31,2
BIT addr 2C Absolute x x x 3 41
BIT dp,X 34 DP Indexed,X x x 2 41,2
BIT addr,X 3C Absolute Indexed,X x x 3 41,3

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BIT #const 89 Immediate x x 217 21

BMI Branch if Minus [Flags affected: none]
BMI nearlabel 30 Program Counter Relative x x x 2 27,8
BNE Branch if Not Equal [Flags affected: none]
BNE nearlabel D0 Program Counter Relative x x x 2 27,8
BPL Branch if Plus [Flags affected: none]
BPL nearlabel 10 Program Counter Relative x x x 2 27,8
BRA Branch Always [Flags affected: none]
BRA nearlabel 80 Program Counter Relative x x 2 38
BRK Break [Flags affected: b,i (6502) b,d,i (65C02/65816 Emulation) d,i (65816
Native)]
18
BRK 00 Stack/Interrupt x x x 2 79
BRL Branch Long Always [Flags affected: none]
Program Counter Relative
BRL label 82 x 3 4
Long
BVC Branch if Overflow Clear [Flags affected: none]
BVC nearlabel 50 Program Counter Relative x x x 2 27,8
BVS Branch if Overflow Set [Flags affected: none]
BVS nearlabel 70 Program Counter Relative x x x 2 27,8
CLC Clear Carry [Flags affected: c]
CLC 18 Implied x x x 1 2
CLD Clear Decimal Mode Flag [Flags affected: d]
CLD D8 Implied x x x 1 2
CLI Clear Interrupt Disable Flag [Flags affected: i]
CLI 58 Implied x x x 1 2
CLV Clear Overflow Flag [Flags affected: v]
CLV B8 Implied x x x 1 2
CMP Compare Accumulator With Memory [Flags affected: n,z,c]
CMP (dp,X) C1 DP Indexed Indirect,X x x x 2 61,2
CMP sr,S C3 Stack Relative x 2 41
CMP dp C5 Direct Page x x x 2 31,2
CMP [dp] C7 DP Indirect Long x 2 61,2
CMP #const C9 Immediate x x x 217 21
CMP addr CD Absolute x x x 3 41
CMP long CF Absolute Long x 4 51
CMP (dp),Y D1 DP Indirect Indexed, Y x x x 2 51,2,3
CMP (dp) D2 DP Indirect x x 2 51,2
CMP (sr,S),Y D3 SR Indirect Indexed,Y x 2 71
CMP dp,X D5 DP Indexed,X x x x 2 41,2

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DP Indirect Long Indexed,

CMP [dp],Y D7 x 2 61,2
Y
CMP addr,Y D9 Absolute Indexed,Y x x x 3 41,3
CMP addr,X DD Absolute Indexed,X x x x 3 41,3
CMP long,X DF Absolute Long Indexed,X x 4 51
COP Co-Processor Enable [Flags affected: d,i]
COP const 02 Stack/Interrupt x 218 79
CPX Compare Index Register X with Memory [Flags affected: n,z,c]
CPX #const E0 Immediate x x x 219 210
CPX dp E4 Direct Page x x x 2 32,10
CPX addr EC Absolute x x x 3 410
CPY Compare Index Register Y with Memory [Flags affected: n,z,c]
CPY #const C0 Immediate x x x 219 210
CPY dp C4 Direct Page x x x 2 32,10
CPY addr CC Absolute x x x 3 410
DEC Decrement [Flags affected: n,z]
DEC A 3A Accumulator x x 1 2
DEC dp C6 Direct Page x x x 2 52,5
DEC addr CE Absolute x x x 3 65
DEC dp,X D6 DP Indexed,X x x x 2 62,5
DEC addr,X DE Absolute Indexed,X x x x 3 75,6
DEX Decrement Index Register X [Flags affected: n,z]
DEX CA Implied x x x 1 2
DEY Decrement Index Register Y [Flags affected: n,z]
DEY 88 Implied x x x 1 2
EOR Exclusive-OR Accumulator with Memory [Flags affected: n,z]
EOR (dp,X) 41 DP Indexed Indirect,X x x x 2 61,2
EOR sr,S 43 Stack Relative x 2 41
EOR dp 45 Direct Page x x x 2 31,2
EOR [dp] 47 DP Indirect Long x 2 61,2
EOR #const 49 Immediate x x x 217 21
EOR addr 4D Absolute x x x 3 41
EOR long 4F Absolute Long x 4 51
EOR (dp),Y 51 DP Indirect Indexed, Y x x x 2 51,2,3
EOR (dp) 52 DP Indirect x x 2 51,2
EOR (sr,S),Y 53 SR Indirect Indexed,Y x 2 71
EOR dp,X 55 DP Indexed,X x x x 2 41,2
DP Indirect Long Indexed,
EOR [dp],Y 57 x 2 61,2
Y

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EOR addr,Y 59 Absolute Indexed,Y x x x 3 41,3

EOR addr,X 5D Absolute Indexed,X x x x 3 41,3
EOR long,X 5F Absolute Long Indexed,X x 4 51
INC Increment [Flags affected: n,z]
INC A 1A Accumulator x x 1 2
INC dp E6 Direct Page x x x 2 52,5
INC addr EE Absolute x x x 3 65
INC dp,X F6 DP Indexed,X x x x 2 62,5
INC addr,X FE Absolute Indexed,X x x x 3 75,6
INX Increment Index Register X [Flags affected: n,z]
INX E8 Implied x x x 1 2
INY Increment Index Register Y [Flags affected: n,z]
INY C8 Implied x x x 1 2
JMP Jump [Flags affected: none][Alias: JML for all Long addressing modes]
JMP addr 4C Absolute x x x 3 3
JMP long 5C Absolute Long x 4 4
JMP (addr) 6C Absolute Indirect x x x 3 511,12
JMP (addr,X) 7C Absolute Indexed Indirect x x 3 6
JMP [addr] DC Absolute Indirect Long x 3 6
JSR Jump to Subroutine [Flags affected: none][Alias: JSL for Absolute Long]
JSR addr 20 Absolute x x x 3 6
JSR long 22 Absolute Long x 4 8
JSR (addr,X)) FC Absolute Indexed Indirect x 3 8
LDA Load Accumulator from Memory [Flags affected: n,z]
LDA (dp,X) A1 DP Indexed Indirect,X x x x 2 61,2
LDA sr,S A3 Stack Relative x 2 41
LDA dp A5 Direct Page x x x 2 31,2
LDA [dp] A7 DP Indirect Long x 2 61,2
LDA #const A9 Immediate x x x 217 21
LDA addr AD Absolute x x x 3 41
LDA long AF Absolute Long x 4 51
LDA (dp),Y B1 DP Indirect Indexed, Y x x x 2 51,2,3
LDA (dp) B2 DP Indirect x x 2 51,2
LDA (sr,S),Y B3 SR Indirect Indexed,Y x 2 71
LDA dp,X B5 DP Indexed,X x x x 2 41,2
DP Indirect Long Indexed,
LDA [dp],Y B7 x 2 61,2
Y
LDA addr,Y B9 Absolute Indexed,Y x x x 3 41,3
LDA addr,X BD Absolute Indexed,X x x x 3 41,3

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LDA long,X BF Absolute Long Indexed,X x 4 51

LDX Load Index Register X from Memory [Flags affected: n,z]
LDX #const A2 Immediate x x x 2 19 210
LDX dp A6 Direct Page x x x 2 32,10
LDX addr AE Absolute x x x 3 410
LDX dp,Y B6 DP Indexed,Y x x x 2 42,10
LDX addr,Y BE Absolute Indexed,Y x x x 3 43,10
LDY Load Index Register Y from Memory [Flags affected: n,z]
LDY #const A0 Immediate x x x 2 19 210
LDY dp A4 Direct Page x x x 2 32,10
LDY addr AC Absolute x x x 3 410
LDY dp,X B4 DP Indexed,X x x x 2 42,10
LDY addr,X BC Absolute Indexed,X x x x 3 43,10
LSR Logical Shift Memory or Accumulator Right [Flags affected: n,z,c]
LSR dp 46 Direct Page x x x 2 52,5
LSR A 4A Accumulator x x x 1 2
LSR addr 4E Absolute x x x 3 65
LSR dp,X 56 DP Indexed,X x x x 2 62,5
LSR addr,X 5E Absolute Indexed,X x x x 3 75,6
MVN Block Move Negative [Flags affected: none][Registers: X,Y,C]
MVN
54 Block Move x 3 13
srcbk,destbk
MVP Block Move Positive [Flags affected: none][Registers: X,Y,C]
MVN
44 Block Move x 3 13
srcbk,destbk
NOP No Operation [Flags affected: none]
NOP EA Implied x x x 1 2
ORA OR Accumulator with Memory [Flags affected: n,z]
ORA (dp,X) 01 DP Indexed Indirect,X x x x 2 61,2
ORA sr,S 03 Stack Relative x 2 41
ORA dp 05 Direct Page x x x 2 31,2
ORA [dp] 07 DP Indirect Long x 2 61,2
ORA #const 09 Immediate x x x 217 21
ORA addr 0D Absolute x x x 3 41
ORA long 0F Absolute Long x 4 51
ORA (dp),Y 11 DP Indirect Indexed, Y x x x 2 51,2,3
ORA (dp) 12 DP Indirect x x 2 51,2
ORA (sr,S),Y 13 SR Indirect Indexed,Y x 2 71
ORA dp,X 15 DP Indexed,X x x x 2 41,2

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DP Indirect Long Indexed,

ORA [dp],Y 17 x 2 61,2
Y
ORA addr,Y 19 Absolute Indexed,Y x x x 3 41,3
ORA addr,X 1D Absolute Indexed,X x x x 3 41,3
ORA long,X 1F Absolute Long Indexed,X x 4 51
PEA Push Effective Absolute Address [Flags affected: none]
PEA addr F4 Stack (Absolute) x 3 5
PEI Push Effective Indirect Address [Flags affected: none]
PEI (dp) D4 Stack (DP Indirect) x 2 62
PER Push Effective PC Relative Indirect Address [Flags affected: none]
PER label 62 Stack (PC Relative Long) x 3 6
PHA Push Accumulator [Flags affected: none]
PHA 48 Stack (Push) x x x 1 31
PHB Push Data Bank Register [Flags affected: none]
PHB 8B Stack (Push) x 1 3
PHD Push Direct Page Register [Flags affected: none]
PHD 0B Stack (Push) x 1 4
PHK Push Program Bank Register [Flags affected: none]
PHK 4B Stack (Push) x 1 3
PHP Push Processor Status Register [Flags affected: none]
PHP 08 Stack (Push) x x x 1 3
PHX Push Index Register X [Flags affected: none]
PHX DA Stack (Push) x x 1 310
PHY Push Index Register Y [Flags affected: none]
PHY 5A Stack (Push) x x 1 310
PLA Pull Accumulator [Flags affected: n,z]
PLA 68 Stack (Pull) x x x 1 41
PLB Pull Data Bank Register [Flags affected: n,z]
PLB AB Stack (Pull) x 1 4
PLD Pull Direct Page Register [Flags affected: n,z]
PLD 2B Stack (Pull) x 1 5
PLP Pull Processor Status Register [Flags affected: n,z]
PLP 28 Stack (Pull) x x x 1 4
PLX Pull Index Register X [Flags affected: n,z]
PLX FA Stack (Pull) x x 1 410
PLY Pull Index Register Y [Flags affected: n,z]
PLY 7A Stack (Pull) x x 1 410
REP Reset Processor Status Bits [Flags affected: all except b per operand]
REP #const C2 Immediate x 2 3

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ROL Rotate Memory or Accumulator Left [Flags affected: n,z,c]

ROL dp 26 Direct Page x x x 2 52,5
ROL A 2A Accumulator x x x 1 2
ROL addr 2E Absolute x x x 3 65
ROL dp,X 36 DP Indexed,X x x x 2 62,5
ROL addr,X 3E Absolute Indexed,X x x x 3 75,6
ROR Rotate Memory or Accumulator Right [Flags affected: n,z,c]
ROR dp 66 Direct Page x x x 2 52,5
ROR A 6A Accumulator x x x 1 2
ROR addr 6E Absolute x x x 3 65
ROR dp,X 76 DP Indexed,X x x x 2 62,5
ROR addr,X 7E Absolute Indexed,X x x x 3 75,6
RTI Return from Interrupt [Flags affected: all except b]
RTI 40 Stack (RTI) x x x 1 69
RTL Return from Subroutine Long [Flags affected: none]
RTL 6B Stack (RTL) x 1 6
RTS Return from Subroutine [Flags affected: none]
RTS 60 Stack (RTS) x x x 1 6
SBC Subtract with Borrow from Accumulator [Flags affected: n,v,z,c]
SBC (dp,X) E1 DP Indexed Indirect,X x x x 2 61,2,4
SBC sr,S E3 Stack Relative x 2 41,4
SBC dp E5 Direct Page x x x 2 31,2,4
SBC [dp] E7 DP Indirect Long x 2 61,2,4
SBC #const E9 Immediate x x x 217 21,4
SBC addr ED Absolute x x x 3 41,4
SBC long EF Absolute Long x 4 51,4
SBC (dp),Y F1 DP Indirect Indexed, Y x x x 2 51,2,3,4
SBC (dp) F2 DP Indirect x x 2 51,2,4
SBC (sr,S),Y F3 SR Indirect Indexed,Y x 2 71,4
SBC dp,X F5 DP Indexed,X x x x 2 41,2,4
DP Indirect Long Indexed,
SBC [dp],Y F7 x 2 61,2,4
Y
SBC addr,Y F9 Absolute Indexed,Y x x x 3 41,3,4
SBC addr,X FD Absolute Indexed,X x x x 3 41,3,4
SBC long,X FF Absolute Long Indexed,X x 4 51,4
SEC Set Carry Flag [Flags affected: c]
SEC 38 Implied x x x 1 2
SED Set Decimal Flag [Flags affected: d]
SED F8 Implied x x x 1 2

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SEI Set Interrupt Disable Flag [Flags affected: i]

SEI 78 Implied x x x 1 2
SEP Set Processor Status Bits [Flags affected: all except b per operand]
SEP E2 Immediate x 2 3
STA Store Accumulator to Memory [Flags affected: none]
STA (dp,X) 81 DP Indexed Indirect,X x x x 2 61,2
STA sr,S 83 Stack Relative x 2 41
STA dp 85 Direct Page x x x 2 31,2
STA [dp] 87 DP Indirect Long x 2 61,2
STA addr 8D Absolute x x x 3 41
STA long 8F Absolute Long x 4 51
STA (dp),Y 91 DP Indirect Indexed, Y x x x 2 61,2
STA (dp) 92 DP Indirect x x 2 51,2
STA (sr,S),Y 93 SR Indirect Indexed,Y x 2 71
STA dpX 95 DP Indexed,X x x x 2 41,2
DP Indirect Long Indexed,
STA [dp],Y 97 x 2 61,2
Y
STA addr,Y 99 Absolute Indexed,Y x x x 3 51
STA addr,X 9D Absolute Indexed,X x x x 3 51
STA long,X 9F Absolute Long Indexed,X x 4 51
STP Stop Processor [Flags affected: none]
STP DB Implied x 1 314
STX Store Index Register X to Memory [Flags affected: none]
STX dp 86 Direct Page x x x 2 32,10
STX addr 8E Absolute x x x 3 410
STX dp,Y 96 DP Indexed,Y x x x 2 42,10
STY Store Index Register Y to Memory [Flags affected: none]
STY dp 84 Direct Page x x x 2 32,10
STY addr 8C Absolute x x x 3 410
STY dp,X 94 DP Indexed,X x x x 2 42,10
STZ Store Zero to Memory [Flags affected: none]
STZ dp 64 Direct Page x x 2 31,2
STZ dp,X 74 DP Indexed,X x x 2 41,2
STZ addr 9C Absolute x x 3 41
STZ addr,X 9E Absolute Indexed,X x x 3 51
TAX Transfer Accumulator to Index Register X [Flags affected: n,z]
TAX AA Implied x x x 1 2
TAY Transfer Accumulator to Index Register Y [Flags affected: n,z]
TAY A8 Implied x x x 1 2

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TCD Transfer 16-bit Accumulator to Direct Page Register [Flags affected: n,z]
TCD 5B Implied x 1 2
TCS Transfer 16-bit Accumulator to Stack Pointer [Flags affected: none]
TCS 1B Implied x 1 2
TDC Transfer Direct Page Register to 16-bit Accumulator [Flags affected: n,z]
TDC 7B Implied x 1 2
TRB Test and Reset Memory Bits Against Accumulator [Flags affected: z]
TRB dp 14 Direct Page x x 2 52,5
TRB addr 1C Absolute x x 3 63
TSB Test and Set Memory Bits Against Accumulator [Flags affected: z]
TSB dp 04 Direct Page x x 2 52,5
TSB addr 0C Absolute x x 3 65
TSC Transfer Stack Pointer to 16-bit Accumulator [Flags affected: n,z]
TSC 3B Implied x 1 2
TSX Transfer Stack Pointer to Index Register X [Flags affected: n,z]
TSX BA Implied x x x 1 2
TXA Transfer Index Register X to Accumulator [Flags affected: n,z]
TXA 8A Implied x x x 1 2
TXS Transfer Index Register X to Stack Pointer [Flags affected: none]
TXS 9A Implied x x x 1 2
TXY Transfer Index Register X to Index Register Y [Flags affected: n,z]
TXY 9B Implied x 1 2
TYA Transfer Index Register Y to Accumulator [Flags affected: n,z]
TYA 98 Implied x x x 1 2
TYX Transfer Index Register Y to Index Register X [Flags affected: n,z]
TYX BB Implied x 1 2
WAI Wait for Interrupt [Flags affected: none]
WAI CB Implied x 1 315
WDM Reserved for Future Expansion [Flags affected: none (subject to change)]
16
WDM 42 n/a x 2 n/a16
XBA Exchange B and A 8-bit Accumulators [Flags affected: n,z]
XBA EB Implied x 1 3
XCE Exchange Carry and Emulation Flags [Flags affected: m,b/x,c,e]
XCE FB Implied x 1 2

NOTES

1 Add 1 cycle if m=0 (16-bit memory/accumulator)

2 Add 1 cycle if low byte of Direct Page Register is non-zero
3 Add 1 cycle if adding index crosses a page boundary
4 Add 1 cycle if 65C02 and d=1 (65C02 in decimal mode)
5 Add 2 cycles if m=0 (16-bit memory/accumulator)

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6 Subtract 1 cycle if 65C02 and no page boundary crossed

7 Add 1 cycle if branch is taken
8 Add 1 cycle if branch taken crosses page boundary on 6502, 65C02, or 65816's 6502 emulation mode (e=1)
9 Add 1 cycle for 65816 native mode (e=0)
10 Add 1 cycle if x=0 (16-bit index registers)
11 Add 1 cycle if 65C02
12 6502: Yields incorrect results if low byte of operand is $FF (i.e., operand is $xxFF)
13 7 cycles per byte moved
14 Uses 3 cycles to shut the processor down: additional cycles are required by reset to restart it
15 Uses 3 cycles to shut the processor down: additional cycles are required by interrupt to restart it
16 Byte and cycle counts subject to change in future processors which expand WDM into 2-byte opcode portions of instructions of
varying lengths
17 Add 1 byte if m=0 (16-bit memory/accumulator)
18 Opcode is 1 byte, but program counter value pushed onto stack is incremented by 2 allowing for optional signature byte
19 Add 1 byte if x=0 (16-bit index registers)

Copyright © 1996 Creative Micro Designs, Inc.

Reprinted with permission from Commodore World magazine, Issue #16.

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