Z80 and R800 Assembly/Machine Language Op-code Tables

Written by "Cyberknight" Masao Kawata.
E-Mail: cyberknight@catsrule.garfield.com
Home Page : http://welcome.to/unicorndreams
Revised: 1999-May-25 Tuesday.

These tables are compilations of different sources, including Z80 instruction set tables and an article of the Japanese "MSX Magazine" (issue of 1990-Nov.) with R800 Assembly.

Available tables:

• Instructions sorted by Z80 mnemonics (compact)
• Fast Reference (sorted by Z80 mnemonics)
• Fast Reference (sorted op-codes)

Tables entries:

• Z80 Assembly: Z80 official Assembly instructions.
• R800 Assembly: R800 official Assembly instructions.
• Operation: description of instruction's operations in symbolic language.
• Description: description of instruction in natural language.
• Remarks: remarks about the instruction.

• Flags: description of register F bits' reaction to the instruction execution:

  .	(flag not modified)
  *	(flag modified by the instruction)
  0	(flag reset), 1 (flag set)
  p	("parity/overflow" flag indicates parity)
  o	("parity/overflow" flag indicates overflow state)
  ?	(flag result is officially undocumented)
  $	(if .bc becomes zero, flag is set to 0, else to 1)
  %	(if .a = [.hl], then flag is set to 1, else to 0)
  !	(if .b becomes zero, flag is set to 1, else to 0)
  I	(copies the value of IFF into the flag)

  The flags are:

  S	(sign, .f{7})
  Z	(zero, .f{6})
  H	(half-carry, .f{4})
  P	(parity/overflow, .f{3})
  N	(subtraction, .f{1})
  C	(carry, .f{0})

• Op-codes: the codes in Machine Language (binary and hexadecimal [Hex]).
• B: length of the instruction in bytes.
• Z*: time spent by a Z80 to execute the instruction, in clock cycles.
• R*: time spent by a R800 to execute the instruction, in clock cycles.

* The time spent by each instruction depends on the hardware architecture. MSX uses RAS/CAS memory banks, so some "wait states" may be generated when accessing memory, even when just reading the program op-codes. MSX turbo R is somehow optimized so it avoids some wait-states when running in R800 mode.

Flag Results

The kind of modification each instruction makes on the flags depends on the results of the operation. Some of the most important results are:

• C: it generally results zero, but is set to 1 if an operation result cannot be hold in the register (sums with results larger than 255 for 8 bit registers, larger than 65535 for 16 bit registers and subtractions that result less than zero). Note that instructions that use increment and decrement operations (INC, DEC, INI, OTIR etc.) never affect the Carry flag. Shift and Rotation instructions don't use this flag as an overflow sign, but for their own purpose as a bit carrier (the difference in the concepts is subtle but important).
• Z: it generally results zero, but is set to 1 if a sum's or subtraction's result is zero.
• N: it is set to 1 by subtraction operations and to zero by sums.

Note that INC and DEC instructions for 16 bit registers don't affect any flag.

Definitions used in the tables:

Z80 8 bit registers
	000	001	010	011	100	101	110	111
r	b	c	d	e	h	l		a

R800 8 bit registers
	000	001	010	011	100	101	110	111
r	.b	.c	.d	.e	.h	.l		.a
u	.b	.c	.d	.e	.ixh	.ixl		.a
v	.b	.c	.d	.e	.iyh	.iyl		.a
p					.ixh	.ixl
q					.iyh	.iyl

Z80 16 bit registers
	00	01	10	11
rr	bc	de	hl	af
ss	bc	de	hl	sp
pp	bc	de	ix	sp
qq	bc	de	iy	sp

R800 16 bit registers
	00	01	10	11
rr	.bc	.de	.hl	.af
ss	.bc	.de	.hl	.sp
pp	.bc	.de	.ix	.sp
qq	.bc	.de	.iy	.sp

Other Registers
Z80	R800	Name
i	.i	interrupt vector
r	.r	refresh register
pc	.pc	program counter

Bits
{b}	bit b (3 bits number)
{x..y}	bit range x..y
IFF	interrupt flip-flop
C	1st bit of .f
N	2nd bit of .f
P	4th bit of .f
H	5th bit of .f
Z	7th bit of .f
S	8th bit of .f

Index Register Modifiers (Z80/R800)
Bin Hex	DDH 11011101B	FDH 11111101B
ii	ix/.ix	iy/.iy

Reset/Break Addresses
	000	001	010	011	100	101	110	111
k	00H	08H	10H	18H	20H	28H	30H	38H

Symbolic operands
+	add
-	subtract
×	multiply
÷	divide
<<	assign
<=>	exchange
<	less than
>	greater than
=	equal
[n]	I/O port n
[.c]	I/O port defined by .c
[nn]	address pointer

Numbers
n	8 bits
d	-128..+127
nn	16 bits
nnl	nn "LSB"
nnh	nn "MSB"

Logical Operations
¬	not
&	and
#	or
^	xor

Symbolic registers
ssl	ss LSB
ssh	ss MSB
rrl	rr LSB
rrh	rr MSB
iil	ii LSB
iih	ii MSB
pcl	pc/.pc LSB
pch	pc/.pc MSB
tmp	temporary

Register F/.F
bit	7	6	5	4	3	2	1	0
flag	S	Z		H	P		N	C

Notes:

• Some R800 exclusive instructions may also work on most Z80, but it's not granted. To support compatibility, don't use them in MSX programs. Multiplication instruction are known to work only with R800.
• The destiny address off-set of all relative jumps is calculated based on the next address immediately after the jump op-code itself. Thus, a zero off-set will make the processor jump exactly to the next instruction (it will execute the next instruction as if no jump was made); a -2 off-set will make the processor jump back to the jump op-code itself, because all relative jump op-codes are 2 bytes long, and so on. It is valid also to the DJNZ/DBNZ instruction.
• The EX AF,AF'/XCH .AF,.AF' and POP AF/POP .AF instructions does not modify any flag by themselves, but, due to their operations, value of register F may be changed.
• Assembly instructions that use index registers IX or IY and requires a numeric off-set may have it ommited if off-set is zero. Examples: "ld a,(ix+0)" may appear as "ld a,(ix)"; "bit 0,[.ix+0]" may appear as "bit 0,[.ix]". Of course, the machine op-codes are not affected, ever presenting the off-set, even if it is zero.
• SHL and SHLA instructions of the R800 are the same, but with two different mnemonics defined, so they can "pair" the SHR and SHRA instruction mnemonics.
• Some op-codes are equivalent, performing the same operations, so they are assigned to the same mnemonics.
• There are currently three tables available: compact, sorted by instruction and sorted by op-code.