Rainbow Electronics T89C5121 - Manual (Page 60)

60
A/T8xC5121
4164G–SCR–07/06
Memory Management
Program Memory All the T8xC5121 versions implement 16 Kbytes of ROM memory, 256 Bytes RAM and
256 Bytes XRAM.
The hardware configuration byte and the split of internal memory spaces depends on
the product and is detailed below.
ROM Configuration Byte Table 44. ROM Configuration Byte Hardware Register
The BLJRB depends of the product version:
• 1: ROM mask version
• 0: EEPROM/CRAM versions
This bit defines if, after reset, either the Customer ROM program or the Bootloader pro-
gram is executed (for In System programming).
Program ROM Lock Bits The program Lock system protects the on-chip program against software piracy.
The T8xC5121 products are delivered with the highest protection level.
Table 45. T8xC5121 Products Protection Level
P = Programmed
7 6 5 4 3 2 1 0
- BLJRB - - - - -
Bit
Number
Bit
Mnemonic Description
7 Reserved
6 BLJRB
Bootloader Jump RAM Bit
Set to configure User Code in ROM
Clear to configure Bootlader in ROM
5-0 Reserved
Program Lock Bits Protection Description
Security
Level LB1 LB2
3 P P
SSOP24 version:
Read function is disabled.But checksum control is still enabled
PLCC52 version:
MOVC instruction executed from external program memory are disabled
from fetching code bytes from internal memory,
EA is sampled and latched on reset.
But checksum control is still enabled.
External execution is possible.