
80C196KB USER’S GUIDE
The CCB can also be programmed during Run-Time
Programming like any other EPROM location.
Data programmed into the CCB takes effect immedi-
ately. If the WRITE lock bit of the CCB is enabled, the
array can no longer be programmed. You should only
program the WRITE lock bit when no further pro-
gramming will be done to the array. If the READ lock
bit is programmed the array can still be programmed
using run-time programming but a data access will only
be performed when the program counter is between
2000H and 3FFFH.
16.8 ROM/EPROM Memory Protection
Options
Write protection is available for EPROM parts, and
read protection is provided for both ROM and
EPROM parts.
Write protection is enabled by clearing the LOC0 bit in
the CCR. When write protection is enabled, the bus
controller will cycle through the write sequence but will
not actually drive data to the EPROM or enable V
PP
to
the EPROM. This protects the entire EPROM (loca-
tions 2000H – 3FFFH) from inadvertent or unautho-
rized programming.
Read protection is enabled by clearing the LOC1 bit of
the CCR. When read protection is selected, the bus
controller will only perform a data read from the ad-
dress range 2020H-202FH (Security Key) and 2040H-
3FFFH if the Slave Program Counter is in the range
2000H-3FFFH. Since the Slave PC can be as many as 4
bytes ahead of the CPU program counter, an instruc-
tion after address 3FFAH may not access protected
memory. Also note the interrupt vectors and CCB are
not read protected.
EA is latched on reset so the device cannot be switched
from internal to external memory by toggling EA.
If the CCR has any protection enabled, the security key
is write protected to keep unauthorized users from ov-
erwriting the key with a known security key.
NOTE:
Substantial effort has been made to provide an excel-
lent program protection scheme. However, Intel can-
not and does not guarantee that these protection
methods will always prevent unauthorized access.
CCB.1
CCB.0
RD
WR
Protection
Lock
Lock
1
1
Array is unprotected. ROM
Dump Mode and all
programming modes are
allowed.
0
1
Array is READ protected. Run-
time programming is allowed.
Auto, Slave, and ROM Dump
Mode are allowed after security
key verification.
1
0
Array is WRITE protected. Auto,
Slave, and ROM Dump Mode
are allowed after security key
verification. Run-time
programming is not allowed.
0
0
Array is READ and WRITE
protected. Auto, Slave, and
ROM Dump Mode are allowed
after security key verification.
Run-time programming is not
allowed.
Figure 16-10
ROM DUMP MODE
You can use the security key and ROM Dump Mode to
dump the internal ROM/EPROM for testing purposes.
The security key is a 16 byte number. The internal
ROM/EPROM must contain the security key at loca-
tions 2020H – 202FH. The user must place the same
security key at external address 4020H – 402FH. Before
doing a ROM dump, the device checks that the keys
match.
93
数控原理与维修
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Содержание 80C196KB Series
Страница 1: ...November 1990 80C196KB User s Guide Order Number 270651 003 http www agreenleaf cn...
Страница 59: ...80C196KB USER S GUIDE Figure 11 7 Ideal A D Characteristic 270651 37 55 http www agreenleaf cn...
Страница 60: ...80C196KB USER S GUIDE Figure 11 8 Actual and Ideal Characteristics 270651 38 56 http www agreenleaf cn...
Страница 61: ...80C196KB USER S GUIDE Figure 11 9 Terminal Based Characteristic 270651 39 57 http www agreenleaf cn...
Страница 70: ...80C196KB USER S GUIDE Figure 13 5 Reset Sequence 80C196KB Reset Sequence 270651 45 66 http www agreenleaf cn...
Страница 83: ...80C196KB USER S GUIDE 270651 80 Figure 15 14 AC Timing Diagrams 79 http www agreenleaf cn...
Страница 84: ...80C196KB USER S GUIDE 270651 81 270651 84 Figure 15 14 AC Timing Diagrams Continued 80 http www agreenleaf cn...