ocpu/ocpu.org

ocpu

GRU ocpu - yet another cpu design

Features

• little endian
• 16-bit

Registers

Register	Category	Description
AL	General	0xA0, 8-bit
AH	General	0xA1, 8-bit
A	General	0xAA, 16-bit
BL	General	0xB0, 8-bit
BH	General	0xB1, 8-bit
B	General	0xBB, 16-bit
CL	General	0xC0, 8-bit
CH	General	0xC1, 8-bit
C	General	0xCC, 16-bit
DL		0xD0, 8-bit 4
DH		0xD1, 8-bit
D		0xDD, 16-bit
EL		0xE0, 8-bit
EH		0xE1, 8-bit
E		0xEE, 16-bit
FL		0xF0, 8-bit
FH		0xF1, 8-bit
F		0xFF, 16-bit
PC	Pointer	Program Counter, 16-bit
SP	Poiner	Stack Pointer, 16-bit
ZF	Flag	Zero Flag
NF	Flag	Negative Flag
CF	Flag	Carry Flag
OF	Flag	Overflow Flag

Instuctions

Instructions	Opcode	Description
MOV	0x01	Place value to register.
		Takes 2 bytes as arguments:
		1 - Opcode of register
		2 - Value
ADD	0x10
ADC	0x11
SUB	0x12
MUL	0x13
DIV	0x14
INC	0x15	Increment
DEC	0x16	Decrement
AND	0x20
OR	0x21
NOR	0x22
XOR	0x23
NAND	0x24
CMP	0x25	Compare
PUSH	0x30	Push to stack
POP	0x31	Pop to stack
JMP	0x40	Jump
JSR	0x41	Jump to subroutine
JC	0x42	Jump with carry
JNC	0x43	Jump without carry
JZ	0x44	Jump if zero
JNZ	0x45	Jump if non-zero
JE	0x46	Jump if equal
JL	0x47	Jump if lower
JH	0x48	Jump if higher
RTS	0x49	Return from subroutine
INB	0x50	Copies value from I/O port to destination
OUTB	0x51	Copies value from operand to I/O port
NOP	0x90	No operation

0x0* - MOV instructions (maybe it will for LDA or something)

0x1* - Arithmetic (ADD, SUB and others)

0x2* - Logic (AND, OR and others)

0x3* - Stack Operations (PUSH, POP)

0x4* - Jumps

0x5* - Ports Operations

0x90 - NOP

TODO: add interrupts

TODO: add HLT

TODO: make instructions for memory use

TODO: add instructions for setting flags

TODO: add more description

TODO: add ALU