AT80C51RD2_08 Datasheet, PDF (60/86 Pages) ATMEL Corporation – 80C51 High Performance ROM 8-bit Microcontroller

16. ROM
16.1 ROM Structure
The T89C51RB2/RC2 ROM memory is divided in two different arrays:
• The code array:16/32K bytes.
• The config byte: 1 byte.
16.1.1
Hardware Config Byte
The config byte sets the starting microcontroller options and the security levels.
The starting options are X2 mode, and XRAM.
7
6
5
4
3
2
1
0
X2
-
-
-
XRAM
-
LB1
LB0
Bit
Number
7
6
5
4
3
2
1-0
Bit
Mnemonic
X2
-
-
-
XRAM
-
LB0-1
Description
X2 Mode
Cleared to force X2 mode (6 clocks per instruction)
Set to force X1 mode, Standard Mode.
Reserved
Reserved
Reserved
XRAM config bit
Set this bit to enable XRAM.
Clear this bit to disable XRAM.
Reserved
User Program ROM Lock Bits
see Table 16-1.
16.2
ROM Lock System
The program Lock system, when programmed, protects the on-chip program against software
piracy.
60 AT8xc51Rx2
4113C–8051–01/08