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Memory Organization: RAM and ROM
2-20
The protection modes are implemented on the C614 as follows. Within the
ROM is a dedicated storage for the block protection word (address 0x7FFE).
The block protection word is divided into two 6-bit fields and two single-bit
fields. The remainder of the 17-bit word is broken into three single-bit fields
which are reserved for future use.
ROM
Block Protection Word
address 0x7FFE (17-bit wide location)
WRITE only 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
R R TM TM TM TM TM TM GP BP R FM FM FM FM FM FM
05 04 03 02 01 00 05 04 03 02 01 00
TM : True Protection Marker (N
TM
) GP : Global Protection (0 value protects)
FM : False Protection Marker (N
FM
) BP : Block Protection (0 value protects)
R : Reserved for future use (must be 1) 1 : Default value of cells on erasure
The two 6-bit fields are designated as the true protection marker, (TM5 through
TM0) and the false protection marker, (FM5 through FM0). When setting up
a partition for partial ROM protection, the address of the partition must be spe-
cified as: