Microcontroller 89C81RD2-IM by ATMEL

First of all, type the name correctly.
There are two chips:
T89C51RD2 from Temic (Atmel Wireless);
AT89C51RD2 from Atmel.
In fact they are two different chips which have similar names but some different features.
For example:
- T89C51RD2 has 63kb of user flash + 1kb of bootloader flash; AT89C51RD2 has 64kb of user flash and 2kb of bootloader ROM;
- T89C51RD2 has 2kb EEPROM; AT89C51RD2 has not EEPROM at all (now there is similar chip called AT89C51ED2 which has 2kb EEPROM);
- T89C51RD2 has 1024 bytes of internal XRAM; AT89C51RD2 has 1792 bytes of XRAM;
- etc, etc, etc...

So looking on chip name you posted I see:
- typpo (C81 should be C51);
- no letters mean you have obtained Temic's chip which indeed has 1024 bytes of XRAM really.

Please read datasheets carefully,

Regards,
Oleg

First of all, type the name correctly.
There are two chips:
T89C51RD2 from Temic (Atmel Wireless);
AT89C51RD2 from Atmel.
In fact they are two different chips which have similar names but some different features.
For example:
- T89C51RD2 has 63kb of user flash + 1kb of bootloader flash; AT89C51RD2 has 64kb of user flash and 2kb of bootloader ROM;
- T89C51RD2 has 2kb EEPROM; AT89C51RD2 has not EEPROM at all (now there is similar chip called AT89C51ED2 which has 2kb EEPROM);
- T89C51RD2 has 1024 bytes of internal XRAM; AT89C51RD2 has 1792 bytes of XRAM;
- etc, etc, etc...

So looking on chip name you posted I see:
- typpo (C81 should be C51);
- no letters mean you have obtained Temic's chip which indeed has 1024 bytes of XRAM really.

Please read datasheets carefully,

Regards,
Oleg

"Please read datasheets carefully"

He probably thinks he actually has the AT89C51RD2.

Some of the Atmel made T89C51RD2 devices are badged "ATMEL 89C51RD2" giving the impression they are AT devices when they are actually T devices. Even the distributors don't seem to know the difference.

Thank You ...