Logica

Logica is an esolang for a 2-bit CPU created by User:H. H. P. M. P. Cole. There is no input/output. It is not Turing-Complete, but it can be, provided infinite storage and infinite-length instructions (this only allows for 16 instructions). Given the constraints, the version of Logica shown here only allows for 2²⁵⁶ possible programs. The CPU has four 2-bit registers.

Logica

Designed by	User:H. H. P. M. P. Cole
Appeared in	2025
Computational class	Linear bounded automata
Reference implementation	Python
Influenced by	2 Bits, 1 Byte, and the 74181 ALU

A typical instruction (all the variables are bits):

a₁a₂ b₁b₂ c₁c₂ d₁d₂d₃d₄ e₁e₂ f₁f₂f₃f₄

The breakdown of the instruction

The four-bit string d₁d₂d₃d₄ specifies the logical operation to be followed. The truth table for the logical operation is as follows:

Input 1	Input 2	Output
0	0	d₁
0	1	d₂
1	0	d₃
1	1	d₄

There are 2⁴ = 16 such logical operations. The operation is simply called "operation d₁d₂d₃d₄".

The two-bit string a₁a₂ denotes the command to be used.

a₁a₂	Command to be followed
00	Jump unconditionally to instruction number f₁f₂f₃f₄.
01	Load the result of operation d₁d₂d₃d₄ with inputs b₁b₂ and c₁c₂ into register e₁e₂.
10	Load the result of operation d₁d₂d₃d₄ with inputs being the numbers in registers b₁b₂ and c₁c₂, into register e₁e₂.
11	End the program.

Python 3 interpreter

The example program given is an infinite loop.

print('Logica Interpreter')
print('by Cole')
print('======================================')
print('Link: https://esolangs.org/wiki/Logica')
print('======================================')

instructionlist = ['1001111000110000',
                   '0000000000000000',
                   '1100000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000',
                   '0000000000000000']

def logicalinstruction(b,c,d):
    e = ''
    for i in range(0,2):
        if b[i] == '0' and c[i] == '0':
            e = e + d[0]
        if b[i] == '0' and c[i] == '1':
            e = e + d[1]
        if b[i] == '1' and c[i] == '0':
            e = e + d[2]
        if b[i] == '1' and c[i] == '1':
            e = e + d[3]
    return e

def binary(a):
    if a == '00':
        return 0
    if a == '01':
        return 1
    if a == '10':
        return 2
    if a == '11':
        return 3

print('Instruction      R0 R1 R2 R3')
print('======================================')

r = ['00','00','00','00']
print('                ',r[0],r[1],r[2],r[3])

i = 0
while instructionlist[i][0:2] != '11':
    a = instructionlist[i][0:2]
    b = instructionlist[i][2:4]
    c = instructionlist[i][4:6]
    d = instructionlist[i][6:10]
    e = instructionlist[i][10:12]
    f = instructionlist[i][12:16]
    if a == '00':
        print(instructionlist[i],r[0],r[1],r[2],r[3])
        i = 4*binary(instructionlist[i][12:14])+binary(instructionlist[i][14:16])
    if a == '01':
        r[binary(e)] = logicalinstruction(b,c,d)
        print(instructionlist[i],r[0],r[1],r[2],r[3])
        i = i + 1
    if a == '10':
        r[binary(e)] = logicalinstruction(r[binary(b)],r[binary(c)],d)
        print(instructionlist[i],r[0],r[1],r[2],r[3])
        i = i + 1
if instructionlist[i][0:2] == '11':
    print(instructionlist[i],r[0],r[1],r[2],r[3])