Scientific RPN Calculator (with ATTINY85)

[deetee]

Wow I like the idea and the ease you are experimenting.

While optimizing the code for scary I tested the replacement of the "hungry" EEPROM.put and EEPROM.get commands with a 4-byte-solution using EEPROM.write and EEPROM.read:

Code:

static void eepromput(unsigned int addr, double x) { // Put float to EEPROM bytewise
  byte n = sizeof(double);  
  union {
    double f;
    byte b[n];
  } u;
  u.f = x;

  memmove(&u.b[0], &u.f, n);
  while (n--) EEPROM.write(addr++, u.b[n - 1]);
}

static double eepromget(unsigned int addr) { // Get float from EEPROM bytewise
  byte n = sizeof(double);
  union {
    double f;
    byte b[n];
  } u;
  
  while (n--) u.b[n - 1] = EEPROM.read(addr++);
  memmove(&u.f, &u.b[0], sizeof(double));
  return (u.f);
}

This should work (and surely can be optimized) - but unfortunately this solution was more "byte hungry" than using the functions of the library.
But maybe you can use this to avoid the lack of your compiler.

Regards
deetee