Philips Semiconductors Product specification
8XC54/58
8XC51FA/FB/FC/80C51FA
8XC51RA+/RB+/RC+/RD+/80C51RA+
80C51 8-bit microcontroller family
8K–64K/256–1K OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33MHz)
2000 Aug 07
48
MASK ROM DEVICES
Security Bits
With none of the security bits programmed the code in the program
memory can be verified. If the encryption table is programmed, the
code will be encrypted when verified. When only security bit 1 (see
Table 11) is programmed, MOVC instructions executed from external
program memory are disabled from fetching code bytes from the
internal memory, EA
is latched on Reset and all further programming
of the EPROM is disabled. When security bits 1 and 2 are
programmed, in addition to the above, verify mode is disabled.
Encryption Array
64 bytes of encryption array are initially unprogrammed (all 1s).
Table 11. Program Security Bits
PROGRAM LOCK BITS
1,
2
SB1 SB2 PROTECTION DESCRIPTION
1 U U No Program Security features enabled.
(Code verify will still be encrypted by the Encryption Array if programmed.)
2 P U MOVC instructions executed from external program memory are disabled from fetching code bytes from
internal memory, EA
is sampled and latched on Reset, and further programming of the EPROM is disabled.
NOTES:
1. P – programmed. U – unprogrammed.
2. Any other combination of the security bits is not defined.
ROM CODE SUBMISSION FOR 8K ROM DEVICES (83C51FA, AND 83C51RA+)
When submitting ROM code for the 8k ROM devices, the following must be specified:
1. 8k byte user ROM data
2. 64 byte ROM encryption key
3. ROM security bits.
ADDRESS
CONTENT BIT(S) COMMENT
0000H to 1FFFH DATA 7:0 User ROM Data
2000H to 203FH KEY 7:0 ROM Encryption Key
FFH = no encryption
2040H SEC 0 ROM Security Bit 1
0 = enable security
1 = disable security
2040H SEC 1 ROM Security Bit 2
0 = enable security
1 = disable security
Security Bit 1: When programmed, this bit has two effects on masked ROM parts:
1. External MOVC is disabled, and
2. EA
is latched on Reset.
Security Bit 2: When programmed, this bit inhibits Verify User ROM.
NOTE: Security Bit 2 cannot be enabled unless Security Bit 1 is enabled.
If the ROM Code file does not include the options, the following information must be included with the ROM code.
For each of the following, check the appropriate box, and send to Philips along with the code:
Security Bit #1:
V Enabled V Disabled
Security Bit #2:
V Enabled V Disabled
Encryption:
V No V Yes If Yes, must send key file.
