This accumulator microprocessor was built during the Computer Organization and Architecture from ICMC discipline and is completely based on what was taught on one compressed version of the Digital Logic and Microprocessor Design with VHDL - Enoch O Hwang book. Moreover, it was done for study purpose.
- 27 Instructions
- 8 Registers (Besides the accumulator), each 8-bits wide
- 32 bytes, each 8-bits wide, of program memory
| Instruction | Encoding | Operation | Comment |
|---|---|---|---|
LDA A,rrr |
0001 0rrr | A <= R[rrr] | Load accumulator from register |
STA rrr,A |
0010 0rrr | R[rrr] <= A | Load register from accumulator |
LDM A,aaaaaa |
0011 0000 00 aaaaaa |
A <= M[aaaaaa] | Load accumulator from memory |
STM aaaaaa,A |
0100 0000 00 aaaaaa |
M[aaaaaa] <= A | Load memory from accumulator |
LDI A,iiiiiiii |
0100 0000 iiiiiiii |
A <= iiiiiiii | Load accumulator with intermediate value (iiiiiiii is a signed number) |
| Instruction | Encoding | Operation | Comment |
|---|---|---|---|
JMP |
0110 0000 00 aaaaaa |
PC <= aaaaaa | Absolute unconditional jump |
JMPR |
0110 smmm | IF (smmm != 0) THEN     IF (s == 0) THEN PC = PC + mmm     ELSE PC = PC - mmm |
Relative unconditional jump (smmm is a sign and magnitude format) |
JZ |
0111 0000 00 aaaaaa |
IF (A == 0) THEN PC = aaaaaa | Absolute jump if A is zero |
JZR |
0111 smmm | IF (A == 0 and smmm != 0) THEN     IF (s == 0) THEN PC = PC + mmm     ELSE PC = PC - mmm |
Relative jump if A is zero (smmm is a sign and magnitude format) |
JNZ |
1000 0000 00 aaaaaa |
IF (A != 0) THEN PC = aaaaaa | Absolute jump if A is not zero |
JNZR |
1000 smmm | IF (A != 0 and smmm != 0) THEN     IF (s == 0) THEN PC = PC + mmm     ELSE PC = PC - mmm |
Relative jump if A is not zero (smmm is a sign and magnitude format) |
JP |
1001 0000 00 aaaaaa |
IF (A > 0) THEN PC = aaaaaa | Absolute jump if A is positive |
JPR |
1000 smmm | IF (A > 0 and smmm != 0) THEN     IF (s == 0) THEN PC = PC + mmm     ELSE PC = PC - mmm |
Relative jump if A is positive (smmm is a sign and magnitude format) |
| Instruction | Encoding | Operation | Comment |
|---|---|---|---|
AND A,rrr |
1010 0rrr | A <= A AND R[rrr] | Accumulator and register |
OR A,rrr |
1011 0rrr | A <= A OR R[rrr] | Accumulator or register |
ADD A,rrr |
1100 0rrr | A <= A + R[rrr] | Accumulator + register |
SUB A,rrr |
1101 0rrr | A <= A - R[rrr] | Accumulator - register |
NOT A |
1110 0000 | A <= NOT A | Inverts the accumulator |
INC A |
1110 0001 | A <= A + 1 | Increments the accumulator |
DEC A |
1110 0010 | A <= A - 1 | Decrements the accumulator |
SHFL A |
1110 0011 | A <= A << 1 | Shifts the accumulator left |
SHFR A |
1110 0100 | A <= A >> 1 | Shifts the accumulator right |
ROTR A |
1110 0101 | A <= RotateRight(A) | Rotates the accumulator right |
| Instruction | Encoding | Operation | Comment |
|---|---|---|---|
IN A |
1111 0000 | A <= input | Input to accumulator |
OUT A |
1111 0001 | output <= A | Output from accumulator |
HALT |
1111 0010 | Halt | Halt execution |
NOP |
0000 0000 | No operation | No operation |