Fast programming of AT89S52 via ArduinoISP. Part one.

The code I've written, just receives the original Intel hex file to the Arduino, which then programs the target chip flash memory. It transfers the same 4 K bytes of flash to the target chip in about four seconds, so it's over twenty times faster.
The version demoed here needs a lot of memory in the Arduino, as that memory holds the full contents of the Intel Hex file, along with a memory image of the data to be programmed to the target chip. My Arduino Mega is fitted with a 512 K byte SRAM expansion (though this sketch only uses about 24 K bytes).
I realize that most people don't have a 5-volt Arduino, that has sufficient SRAM, so I'm working on a modified version that should work on a standard, old school, Arduino Uno or Nano. It should work almost as fast. I'll make a full length video about it, explaining connections, operation, and with the files available for download, once it's debugged and working.