README.md

microcode

Below is documentation for the 3000's microinstructions, as well as the full instruction set currently supported on the 3000.

Microinstructions

Instruction	Description
HLT	Halt (when active this line stops the clock)
RST	Reset (reset the step counter of the instruction)
PCE	Program Counter Enable (program counter will increment on next clock pulse)
PCO	Program Counter Out
PCI	Program Counter In
MI	Memory Address Register In
RO	RAM Out
RI	RAM In (write to RAM)
IO	Instruction Register Out (never used)
II	Instruction Register In
AO	A-register Out
AI	A-register In
BO	B-register Out
BI	B-register In
CO	C-register Out
CI	C-register In
TO	Temp-register Out
TI	Temp-register In
OI	Output-register In (Decimal display)
LCS	LCD Select (Data vs. Command)
LCE	LCD Enable (Actively listening to bus)
EO	ALU Out
EI	ALU In
FI	Flags-register In
NOT	NOT ALU Operation
AND	AND ALU Operation
XOR	XOR ALU Operation
OR	OR ALU Operation
SUM	ADD ALU Operation
TS	Select Temp-register as other operand or all 0s
CAR	Set Carry/Borrow for addition and subtraction
SUB	SUB ALU operation (add but with 1s compliment (2s compliment comes from setting CAR line))
STK	Accessing stack or instruction memory
SO	Stack pointer out
SI	Stack pointer in

Instruction Set

Note: instructions listed with opcode N/A describe the behavior of a whole class of instructions, which have specific opcodes that correspond to the use of specific registers.

Instruction	Opcode	Description
add $r1, $r2	N/A	$r2 = $r2 + $r1
add a, a	0x00
add a, b	0x01
add a, c	0x02
add a, sp	0x03
add b, a	0x04
add b, b	0x05
add b, c	0x06
add b, sp	0x07
add c, a	0x08
add c, b	0x09
add c, c	0x0a
add c, sp	0x0b
addi byte, $r1	N/A	$r1 = $r1 + byte
addi byte, a	0x0c
addi byte, b	0x0d
addi byte, c	0x0e
addi byte, sp	0x0f
addc $r1, $r2	N/A	$r2 = $r2 + $r1 + CF
addc a, a	0x10
addc a, b	0x11
addc a, c	0x12
addc a, sp	0x13
addc b, a	0x14
addc b, b	0x15
addc b, c	0x16
addc b, sp	0x17
addc c, a	0x18
addc c, b	0x19
addc c, c	0x1a
addc c, sp	0x1b
addci byte, $r1	N/A	$r1 = $r1 + byte + CF
addci byte, a	0x1c
addci byte, b	0x1d
addci byte, c	0x1e
addci byte, sp	0x1f
sub $r1, $r2	N/A	$r2 = $r2 - $r1
sub b, a	0x20
sub c, a	0x21
sub a, b	0x22
sub c, b	0x23
sub a, c	0x24
sub b, c	0x25
sub a, sp	0x26
sub b, sp	0x27
sub c, sp	0x28
subi byte, $r1	N/A	$r1 = $r1 - byte
subi byte, a	0x29
subi byte, b	0x2a
subi byte, c	0x2b
subi byte, sp	0x2c
subb $r1, $r2	N/A	$r2 = $r2 - $r1 - CF
subb b, a	0x2d
subb c, a	0x2e
subb a, b	0x2f
subb c, b	0x30
subb a, c	0x31
subb b, c	0x32
subb a, sp	0x33
subb b, sp	0x34
subb c, sp	0x35
subbi byte, $r1	N/A	$r1 = $r1 - byte - CF
subbi byte, a	0x36
subbi byte, b	0x37
subbi byte, c	0x38
subbi byte, sp	0x39
and $r1, $r2	N/A	$r2 = $r2 & $r1
and b, a	0x3a
and c, a	0x3b
and a, b	0x3c
and c, b	0x3d
and a, c	0x3e
and b, c	0x3f
ani byte, $r1	N/A	$r1 = $r1 & byte
ani byte, a	0x40
ani byte, b	0x41
ani byte, c	0x42
or $r1, $r2	N/A	$r2 = $r2 | $r1
or b, a	0x43
or c, a	0x44
or a, b	0x45
or c, b	0x46
or a, c	0x47
or b, c	0x48
ori byte, $r1	N/A	$r1 = $r1 | byte
ori byte, a	0x49
ori byte, b	0x4a
ori byte, c	0x4b
xor $r1, $r2	N/A	$r2 = $r2 ^ $r1
xor b, a	0x4c
xor c, a	0x4d
xor a, b	0x4e
xor c, b	0x4f
xor a, c	0x50
xor b, c	0x51
xri byte, $r1	N/A	$r1 = $r1 ^ byte
xri byte, a	0x52
xri byte, b	0x53
xri byte, c	0x54
not $r1	N/A	$r1 = ~$r1
not a	0x55
not b	0x56
not c	0x57
neg $r1	N/A	$r1 = ~$r1 + 1
neg a	0x58
neg b	0x59
neg c	0x5a
inr $r1	N/A	$r1 = $r1 + 1
inr a	0x5b
inr b	0x5c
inr c	0x5d
inr sp	0x5e
inr2 $r1	N/A	$r1 = $r1 + 2
inr2 a	0x5f
inr2 b	0x60
inr2 c	0x61
inr2 sp	0x62
inr3 $r1	N/A	$r1 = $r1 + 3
inr3 a	0x63
inr3 b	0x64
inr3 c	0x65
inr3 sp	0x66
dcr $r1	N/A	$r1 = $r1 - 1
dcr a	0x67
dcr b	0x68
dcr c	0x69
dcr sp	0x6a
dcr2 $r1	N/A	$r1 = $r1 - 2
dcr2 a	0x6b
dcr2 b	0x6c
dcr2 c	0x6d
dcr2 sp	0x6e
dcr3 $r1	N/A	$r1 = $r1 - 3
dcr3 a	0x6f
dcr3 b	0x70
dcr3 c	0x71
dcr3 sp	0x72
mov $r1, $r2	N/A	$r2 = $r1
mov a, b	0x73
mov a, c	0x74
mov b, a	0x75
mov b, c	0x76
mov c, a	0x77
mov c, b	0x78
mov z, a	0x79
mov z, b	0x7a
mov z, c	0x7b
mov sp, a	0x7c
mov sp, b	0x7d
mov sp, c	0x7e
mvi byte, $r1	N/A	$r1 = byte
mvi byte, a	0x7f
mvi byte, b	0x80
mvi byte, c	0x81
ld $r1, $r2	N/A	$r2 = RAM[$r1]
ld a, a	0x82
ld b, a	0x83
ld c, a	0x84
ld a, b	0x85
ld b, b	0x86
ld c, b	0x87
ld a, c	0x88
ld b, c	0x89
ld c, c	0x8a
st $r1, $r2	N/A	RAM[$r2] = $r1
st a, a	0x8b
st a, b	0x8c
st a, c	0x8d
st b, a	0x8e
st b, b	0x8f
st b, c	0x90
st c, a	0x91
st c, b	0x92
st c, c	0x93
st z, a	0x94
st z, b	0x95
st z, c	0x96
lds byte, $r1	N/A	$r1 = RAM[sp + byte]
lds byte, a	0x97
lds byte, b	0x98
lds byte, c	0x99
sts $r1, byte	N/A	RAM[sp + byte] = $r1
sts a, byte	0x9a
sts b, byte	0x9b
sts c, byte	0x9c
sts z, byte	0x9d
stsi byte_1, byte_2	0x9e	RAM [sp + byte_2] = byte_1
cmp $r1, $r2	N/A	Perform $r1 - $r2 and set flags
cmp a, b	0x9f
cmp a, c	0xa0
cmp a, z	0xa1
cmp b, a	0xa2
cmp b, c	0xa3
cmp b, z	0xa4
cmp c, a	0xa5
cmp c, b	0xa6
cmp c, z	0xa7
cmp z, a	0xa8
cmp z, b	0xa9
cmp z, c	0xaa
cmpi byte/$r1, $r1/byte	N/A	Perform byte/$r1 - $r1/byte and set flags
cmpi a, byte	0xab
cmpi byte, a	0xac
cmpi b, byte	0xad
cmpi byte, b	0xae
cmpi c, byte	0xaf
cmpi byte, c	0xb0
jmp byte	0xb1	PC = byte
je byte	0xb2	if ZF, PC = byte
jne byte	0xb3	if ~ZF, PC = byte
jg byte	0xb4	if ~(SF ^ OF) & ~ZF, PC = byte
jge byte	0xb5	if ~(SF ^ OF), PC = byte
jl byte	0xb6	if (SF ^ OF), PC = byte
jle byte	0xb7	if (SF ^ OF) | ZF, PC = byte
ja byte	0xb8	if (~CF & ~ZF), PC = byte
jae byte	0xb9	if (~CF), PC = byte
jb byte	0xba	if (CF), PC = byte
jbe byte	0xbb	if (CF | ZF), PC = byte
call byte	0xbc	sp += 1, PC += 1, Stack[sp] = PC, PC = byte
ret	0xbd	PC = Stack[sp], sp -= 1
out $r1	N/A	Send $r1 to decimal display
out a	0xbe
out b	0xbf
out c	0xc0
outi byte	0xc1	Send byte to decimal display
dic byte	0xc2	Send command byte to LCD
did byte	0xc3	Send data byte to LCD
dd $r1	N/A	Send $r1 to LCD
dd a	0xc4
dd b	0xc5
dd c	0xc6
hlt	0xc7	Halt
nop	0xc8	No operation