89C51RD2 Datasheet - NXP

89C51RD2, 80C51 8-bit Flash microcontroller family 16KB/32KB/64KB ISP/IAP Flash with 512B/512B/1KB RAM

INTEGRATED CIRCUITS 89C51RB2/89C51RC2/89C51RD2 80C51 8-bit Flash microcontroller family 16KB/32KB/64KB ISP/IAP Flash with 512B/512B/1KB RAM Prelimina.
The 89C51RB2/RC2/RD2 device contains a non-volatile 16kB/32kB/64kB Flash program memory that is both parallel programmable and serial In-System and In.