A mega would be more suitable for this code, memory size and pin's avaliable.
8086 emulation on an arduino. I am currently using this file for ideas, which of course will change in the future.
I am using microcomputer systems: the 8086/8088 family, prentice-hall, 1986 as a guide. Page's 129-134 list the opcode,s in a binary format. pdf pg 26 onwards.
Main code sections. (These may/will change)
typedef struct cpu{ //cpu register's including IP. regs_t regs; //Program status word. ie flags. byte psw; //Instruction queue, some instructions are 6 bytes in length. byte i_q[6]; unsigned int dataBus; unsigned int addressBus; } cpu_t;
typedef struct regs{ //Data registers unsigned int ax; unsigned int bx; unsigned int cx; unsigned int dx;
//pointers unsigned int sp; unsigned int bp; unsigned int si; unsigned int di; unsigned long ip; //should be 20bits in size.
//segments unsigned int cs; unsigned int ss; unsigned int ds; unsigned int es; } regs_t;
To save space I will only be using one cpu_t type.
( each opcode is in a lookup table of 256 entrys, multiple locations can point to a "single" opcode ) Look up table is out, The limitations of the atmega328p memory size limit how big my array can be, a costly switch statement will suffice.
- typedef int (*__opcode_handler_t)(void); return type points to how far forward/backward ? to the next opcode
- I am trying to make each opcode small in size, except the MOV one.
Just a quick note, I am not sure when I will get backto this project