Build your own a programmer for writing intel-HEX file to the 89C51, 89C52 and 89C55, PCB file included, Window version UPLOADER EZ3, EZ3.1,
Programmer for AT89S52 Microcontroller
Connecting the Easy-Downloader V2.0 to a PC with USB port:
Newer PC, or laptop computer may not provides the COM port, instead it has the USB port as a standard serial port. I found a cheap adapter, the FTDI232 USB-COM port converter. The adapter uses FT232RL chip. The adapter provides 6-pins connector. To interface it to the Easy-downloader, we needs only three pins, i.e. TXD, RXD, and GND. The chip itself powered by +5V from USB port.
The Atmel AT89S52 is an 8051 based Full Static CMOS controller with Three-Level Program Memory Lock, 32 I/O lines, 3 Timers/Counters, 8 Interrupts Sources, Watchdog Timer, 2 DPTRs, 8K Flash Memory, 256 Bytes On-chip RAM.
AT89S52 - 8 bit Microcontroller
Compatible with the industry-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.