erase.cpp

#include <stdio.h>
#include <dos.h>

#define BASE 0xD0000

#define ROMADD(X) (volatile unsigned char far *)MK_FP(0xD000, (X))

volatile unsigned char far *unlock1 = ROMADD(0x5555);
volatile unsigned char far *unlock2 = ROMADD(0x2AAA);

#define COMMAND(X) \
        *unlock1 = 0xAA; \
        *unlock2 = 0x55; \
        *unlock1 = (X);

void main() {
        COMMAND(0x90);
        unsigned char manufacturer = *ROMADD(0x0000);
        unsigned char product = *ROMADD(0x0001);
        COMMAND(0xF0);

        int chipid = manufacturer << 8 | product;

        switch (chipid) {
                case 0xbfb5:
                        printf("SST39SF010A\n");
                        break;
                case 0xbfb6:
                        printf("SST39SF020A\n");
                        break;
                case 0xbfb7:
                        printf("SST39SF040\n");
                        break;
                default:
                        printf("Unsupported chip or chip error\n");
                        return;
                        break;
        }

        printf("Erasing now...");
        COMMAND(0x80);
        COMMAND(0x10);

        unsigned char v1 = *ROMADD(0);
        unsigned char v2 = *ROMADD(0);
        while ((v1 & 0x40) != (v2 & 0x40)) {
                v1 = v2;
                v2 = *ROMADD(0);
        }
        printf("done\n");
}