Datasheet

Philips Semiconductors Product specification
80C51/87C51/80C52/87C52
80C51 8-bit microcontroller family
4 K/8 K OTP/ROM low voltage (2.7 V–5.5 V),
low power, high speed (33 MHz), 128/256 B RAM
2000 Aug 07
33
PROGRAMMING* VERIFICATION*
ADDRESS ADDRESS
DATA IN DATA OUT
LOGIC 1 LOGIC 1
LOGIC 0
t
AVQV
t
EHQZ
t
ELQV
t
SHGL
t
GHSL
t
GLGH
t
GHGL
t
AVGL
t
GHAX
t
DVGL
t
GHDX
P1.0–P1.7
P2.0–P2.5
P3.4
(A0 – A12)
PORT 0
P0.0 – P0.7
(D0 – D7)
ALE/PROG
EA/V
PP
P2.7
**
SU01414
t
EHSH
NOTES:
*
FOR PROGRAMMING CONFIGURATION SEE FIGURE 26.
FOR VERIFICATION CONDITIONS SEE FIGURE 28.
** SEE TABLE 8.
Figure 29. EPROM Programming and Verification
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.