Assembler
20bit fixed-length assembler for a simple conceptual robot with a theoretical Turing-complete instruction set.
Machine code syntax:
20 bit per line, grouped by 5 bits.
00000 00000 00000 00000
Legend:
i - bit for instruction code
r - bit for register
m - bit for memory location
x - ignored
Depending on the instruction code, machine code syntax can vary as follows:
Robot-navigation instructions:
5 bits instruction
iiiii xxxxx xxxxx xxxxx
Sensory instruction:
5 bits instruction, 2 bits register, 13 bits memory
iiiii rrmmm mmmmm mmmmm
Jump (goto) command:
5 bits instruction, 13 bits ignored, 2 bits register:
iiiii xxxxx xxxxx xxxrr
Jump (goto) command w/ conditionals:
5 bits instruction, 2 bits register, 13 bits jump in memory address:
iiiii rrmmm mmmmm mmmmm
Arithmetic:
5 bits instruction, 2 bits register A, 2 bits register B, 2 bits register C
iiiii rrrrr rxxxx xxxxx
io Memory:
5 bits instruction, 2 bits register, 13 bits memory address
iiiii rrmmm mmmmm mmmmm
Constant Assignment:
5 bits instruction, 2 bits register, 13 bits constant iiiii rrmmm mmmmm mmmmm
Instruction Codes
by Prof. Solomon See (DLSU, CCS)
0: halt = forces the system to stop
1: moveForward = moves the robot forward in the current direction it is facing
2: rotateLeft = rotate left the direction where the robot is facing
3: rotateRight = rotate left the direction where the robot is facing
4: sense = sense what is in front of the robot where it is currently facing. The remainder 15 bits tells the robot which register to store the data.
5: jump = jump to a code line number. The remainder 15 bits identifies which line number to jump to.
6: jumpeq = jump to a code line number if the value of a register is equal to zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
7: jumpne = jump to a code line number if the value of a register is not equal to zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
8: jumpgt = jump to a code line number if the value of a register is greater than zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
9: jumplt = jump to a code line number if the value of a register is less than zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
10: jumpgte = jump to a code line number if the value of a register is greater than or equal to zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
11: jumplte = jump to a code line number if the value of a register is less than or equal to zero. The first 2 bits after the opcode determines which register to check against. The remainder 13 bits identifies which line number to jump to.
12: add = adds the values of the first and second register and stores it on the third register. The first 2 bits after the opcode represents the first register, the next 2 bits is for the second register and the next 2 bits for the third register. The remainder of the bits are ignored.
13: sub = subtracts the values of the first register to the second register and stores it on the third register. The first 2 bits after the opcode represents the first register, the next 2 bits is for the second register and the next 2 bits for the third register. The remainder of the bits are ignored.
14: mult = multiplies the values of the first and second register and stores it on the third register. The first 2 bits after the opcode represents the first register, the next 2 bits is for the second register and the next 2 bits for the third register. The remainder of the bits are ignored.
15: readmem = reads the value of the memory location and stores it to a register. The first 2 bits after the opcode represents the register, the remaining bits are used to specify the memory address.
16: writemem = writes to the memory location the value of a register. The first 2 bits after the opcode represents the register, the remaining bits are used to specify the memory address.
17: setreg = sets the value of a register to a constant value. The first 2 bits after the opcode represents the register, the remaining bits represent the constant value that will be stored.