char read_char()
{
  unsigned char c = 0;
  SCLK = 0;
  DATA_IO = 1;       // make input
  RESET = 1;
  for (i = 0; i < 8; i++) {
    SCLK = 1;
    c >>= 1;
    SCLK = 0;
    if (DATA_IO == 1) c |= 0x80;
  }
  RESET = 0;
  return c;          // leaves with SCLK, RESET low
}