Philips Semiconductors Product data
P87C51RA2/RB2/RC2/RD2
80C51 8-bit microcontroller family 8KB/16KB/32KB/64KB OTP
with 512B/1KB RAM, low voltage (2.7 to 5.5 V), low power, high
speed (30/33 MHz)
2003 Jan 24
59
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 10) 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 10. 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 (87C51RA2)
When submitting ROM code for the 8k ROM devices, the following must be specified:
1. 8 kbyte 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.
