基于 STC89C52 单片机的简易加减法计算器代码

以下是基于STC89C52单片机的简易加减法计算器的代码，供你参考：

#include <reg52.h>
#include <stdio.h>

sbit KEY1 = P3^2;
sbit KEY2 = P3^3;
sbit KEY3 = P3^4;
sbit KEY4 = P3^5;

sbit D1 = P1^0;
sbit D2 = P1^1;
sbit D3 = P1^2;
sbit D4 = P1^3;

char code Table[] = {
    0x3f, 0x06, 0x5b, 0x4f, 0x66,
    0x6d, 0x7d, 0x07, 0x7f, 0x6f
};

unsigned char num1, num2, flag, oper, result;
unsigned char Stack[4];
unsigned char Top = 0;

void Delay(unsigned int i) {
    while(i--);
}

void Display(unsigned char num) {
    D4 = 1;
    P0 = Table[num%10];
    D4 = 0;
    Delay(5);
    D3 = 1;
    P0 = Table[num/10%10];
    D3 = 0;
    Delay(5);
    D2 = 1;
    P0 = Table[num/100%10];
    D2 = 0;
    Delay(5);
    D1 = 1;
    P0 = Table[num/1000%10];
    D1 = 0;
    Delay(5);
}

void KeyDown() {
    if(!KEY1) {
        Delay(2000);
        if(!KEY1) {
            if(flag == 0) {
                num1 = num1*10 + 1;
                Display(num1);
            } else {
                num2 = num2*10 + 1;
                Display(num2);
            }
        }
    }
    if(!KEY2) {
        Delay(2000);
        if(!KEY2) {
            if(flag == 0) {
                num1 = num1*10 + 2;
                Display(num1);
            } else {
                num2 = num2*10 + 2;
                Display(num2);
            }
        }
    }
    if(!KEY3) {
        Delay(2000);
        if(!KEY3) {
            if(flag == 0) {
                num1 = num1*10 + 3;
                Display(num1);
            } else {
                num2 = num2*10 + 3;
                Display(num2);
            }
        }
    }
    if(!KEY4) {
        Delay(2000);
        if(!KEY4) {
            if(flag == 0) {
                oper = '+';
                flag = 1;
            } else {
                oper = '-';
                flag = 2;
            }
        }
    }
}

void Init() {
    TMOD = 0x01;
    TH0 = 0xfc;
    TL0 = 0x18;
    EA = 1;
    ET0 = 1;
    TR0 = 1;
}

void Time0() interrupt 1 {
    TH0 = 0xfc;
    TL0 = 0x18;
    KeyDown();
}

void Calculate() {
    switch(oper) {
        case '+': result = num1 + num2; break;
        case '-': result = num1 - num2; break;
        default: break;
    }
    Stack[Top++] = result%10;
    Stack[Top++] = result/10%10;
    Stack[Top++] = result/100%10;
    Stack[Top++] = result/1000%10;
    while(Top != 0) {
        Display(Stack[--Top]);
        Delay(10000);
    }
}

void main() {
    Init();
    while(1) {
        if(flag == 2) {
            Calculate();
            flag = 0;
            num1 = 0;
            num2 = 0;
            oper = 0;
        }
    }
}

以上是基于STC89C52单片机的简易加减法计算器的代码，其中包括按键扫描、数码管显示、加减法运算等功能。需要注意的是，代码中的硬件电路需要自行搭建，并且可能需要根据具体情况进行调整。另外，代码中的延时函数只是简单的延时，实际中需要根据具体情况进行调整。