Paul was right

Omega Races uses a Grey Code encoding.

Doing an alta vista search for "Grey Code" I found these wee converter programs
too (after I decoded the EPROM, of course..)

#include <stdio.h>

int main(int args, unsigned char *argc[]) {
        unsigned char num, gnum;
        int j, bit,numbits=8;
        unsigned int mask ;
        if (args!=2) {
        printf("Usage: g2bin GreyCodeNumber\n");
        return(-1);
                }

        gnum=(unsigned char) strtoul(argc[1], (char **)NULL, 16);

/* g2bin is for numbers with bits fewer than 8, it works for only for
numbers with 8 or fewer bits because this transformation depends on the number
of bits in the number */

        if (gnum > 0xff) {
                printf("Number must be smaller than 8 bits\n");
                return(-1);
        }

/* Calculate the binary code equivalent of the gray number */

        num = gnum ^ (gnum >> 0x01) ^ (gnum >> 0x02) ^ (gnum >> 0x03)
        ^ (gnum >> 0x04) ^ (gnum >> 0x05) ^ (gnum >> 0x06) ^ (gnum >> 0x07);

        printf("Decimal binary num is %lu\n", num);
        printf("Decimal grey equivalent is %lu\n", gnum);
        printf("Grey code number Binary Number\n");
        printf(" ");
        bitDump(&gnum, &numbits);
        printf("\t \t");
        bitDump(&num, &numbits);
        printf("\n");
        return(0);
        }
        int bitDump(unsigned char *num, int *numbts){
          int j;
          unsigned long int mask;
          int bit;
          mask = 0x80;
          for (j=0;j<*numbts;j++) {
                bit =(mask & *num) ? 1 : 0;
                printf("%d", bit);
                mask >>=1;
          }
        return(0);
        }

#include <stdio.h>

int main(int args, unsigned char *argc[]) {
        unsigned char num, gnum;
        int j, bit,numbits=8;
        unsigned int mask ;

        if (args!=2) {
           printf("Usage: bin2g HexBinaryNumber\n");
           return(-1);
        }

        if (args>2) {
            printf("Second argument ignored\n");
        }
        num = (unsigned char ) strtoul(argc[1],(char **)NULL, 16);

/* bin2g is for numbers with bits fewer than 8, it works for any number
of bits, but the g2bin depends on the number of bits, currently, 8 */

        if (num > 0xff) {
                printf("Number must be smaller than 8 bits\n");
                return(-1);
        }

/* Calculate the grey code equivalent */

        gnum = num ^ (num >> 0x01);

        printf("Decimal binary num is %lu\n", num);
        printf("Decimal grey equivalent is %lu\n", gnum);
        printf("Grey code number Binary Number\n");
        printf(" ");
        bitDump(&num, &numbits);
        printf("\t \t");
        bitDump(&gnum, &numbits);
        printf("\n");
        return(0);
        }

/* bitDump function takes the number and the number of bits and prints
   the binary equivalent of the number */

        int bitDump(unsigned char *num, int *numbts){
          int j;
          unsigned long int mask;
          int bit;
          mask = 0x80;
          for (j=0;j<*numbts;j++) {
                bit =(mask & *num) ? 1 : 0;
                printf("%d", bit);
                mask >>=1;
          }
        return(0);
        }
Received on Thu Jul 24 09:17:11 1997