1978 BASIC Life line-by-line ported to C#

Life1978v1.cs

// This is a line-for-line C# port of a 1978 BASIC implementation of Conway's Life;
// bugs are included as they were in the original program.
// See https://ericlippert.com/2021/02/17/life-part-38/ and 
// https://ericlippert.com/2021/02/23/life-part-39/ for details.

using System;
using static System.Math;

public class Program
{
    static void TAB(int x) => Console.CursorLeft = x;
    static void PRINT(string s = "") => Console.WriteLine(s);
    static void PRINTSEMI(string s) => Console.Write(s);
    static string INPUT() => Console.ReadLine();
    static string LEFT(string s, int length) => s.Substring(0, Min(length, s.Length));
    static string RIGHT(string s, int length) => s.Substring(s.Length - length);
    static int LEN(string s) => s.Length;
    static string MID(string s, int index, int length) => s.Substring(index - 1, length);

    public static void Main()
    {
        TAB(34);
        PRINT("LIFE");
        TAB(15);
        PRINT("CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY");
        PRINT();
        PRINT();
        PRINT();
        PRINT("ENTER YOUR PATTERN:");
        int X1 = 1;
        int Y1 = 1;
        int X2 = 24;
        int Y2 = 70;
        int[,] A = new int[24 + 1, 70 + 1];
        string[] B = new string[24 + 1];
        int C = 1;
    _30:
        B[C] = INPUT();
        if (B[C] == "DONE")
        {
            B[C] = "";
            goto _80;
        }
        if (LEFT(B[C], 1) == ".")
        {
            B[C] = " " + RIGHT(B[C], LEN(B[C]) - 1);
        }
        C = C + 1;
        goto _30;
    _80:
        C = C - 1;
        int L = 0;
        int P = 0;
        for (int X = 1; X <= C - 1; X += 1)
        {
            if (LEN(B[X]) > L)
            {
                L = LEN(B[X]);
            }
        }
        X1 = 11 - C / 2;
        Y1 = 33 - L / 2;
        for (int X = 1; X <= C; X += 1)
        {
            for (int Y = 1; Y <= LEN(B[X]); Y += 1)
            {
                if (MID(B[X], Y, 1) != " ")
                {
                    A[X1 + X, Y1 + Y] = 1;
                    P = P + 1;
                }
            }
        }
        PRINT();
        PRINT();
        PRINT();
        int G = 0;
        int I9 = 0;
    _210:
        PRINTSEMI("GENERATION:" + G + "POPULATION:" + P);
        if (I9 != 0)
        {
            PRINTSEMI("INVALID!");
        }
        int X3 = 24;
        int Y3 = 70;
        int X4 = 1;
        int Y4 = 1;
        P = 0;
        G = G + 1;
        for (int X = 1; X <= X1 - 1; X += 1)
        {
            PRINT();
        }
        for (int X = X1; X <= X2; X += 1)
        {
            PRINT();
            for (int Y = Y1; Y <= Y2; Y += 1)
            {
                if (A[X, Y] == 2)
                {
                    A[X, Y] = 0;
                    goto _270;
                }
                if (A[X, Y] == 3)
                {
                    A[X, Y] = 1;
                    goto _261;
                }
                if (A[X, Y] != 1)
                {
                    goto _270;
                }
            _261:
                TAB(Y);
                PRINTSEMI("*");
                if (X < X3)
                {
                    X3 = X;
                }
                if (X > X4)
                {
                    X4 = X;
                }
                if (Y < Y3)
                {
                    Y3 = Y;
                }
                if (Y > Y4)
                {
                    Y4 = Y;
                }
            _270:;
            }
        }
        for (int X = X2 + 1; X <= 24; X += 1)
        {
            PRINT();
        }
        X1 = X3;
        X2 = X4;
        Y1 = Y3;
        Y2 = Y4;
        if (X1 < 3)
        {
            X1 = 3;
            I9 = -1;
        }
        if (X2 > 22)
        {
            X2 = 22;
            I9 = -1;
        }
        if (Y1 < 3)
        {
            Y1 = 3;
            I9 = -1;
        }
        if (Y2 > 68)
        {
            Y2 = 68;
            I9 = -1;
        }
        P = 0;
        for (int X = X1 - 1; X <= X2 + 1; X += 1)
        {
            for (int Y = Y1 - 1; Y <= Y2 + 1; Y += 1)
            {
                C = 0;
                for (int I = X - 1; I <= X + 1; I += 1)
                {
                    for (int J = Y - 1; J <= Y + 1; J += 1)
                    {
                        if (A[I, J] == 1 || A[I, J] == 2)
                        {
                            C = C + 1;
                        }
                    }
                }
                if (A[X, Y] == 0)
                {
                    goto _610;
                }
                if (C < 3 || C > 4)
                {
                    A[X, Y] = 2;
                    goto _600;
                }
                P = P + 1;
            _600:
                goto _620;
            _610:
                if (C == 3)
                {
                    A[X, Y] = 3;
                    P = P + 1;
                }
            _620:;
            }
        }
        X1 = X1 - 1;
        Y1 = Y1 - 1;
        X2 = X2 + 1;
        Y2 = Y2 + 1;
        goto _210;
    }
}