AT89S52 Arduino programmer. Fast, and simple to use.

You just use the XMODEM protocol to send your hex file to the Arduino at 115200 baud, and it then programs the AT89S52 (or 51) using the Arduino A0, A1, A2, A3, lines attached to RST, SCK, MISO, and MOSI respectively.

Edit: 2025-03-11 Found a bug which prevented very small hex files from being uploaded. I've fixed it and updated the download .zip file for the sketch (see below).

Works with many different Arduinos: Uno R3, Nano, etc. Leonardo, Micro, Pro Micro and other ATmega32U4-based designs, Mega 1280 and 2560, Uno R4 (with the Renesas chip), ... probably many more, but remember that the AT89S52 board may be operating at 5V, so beware 3.3V Arduinos.