MOTOROLA M68000 FAMILY Programmer's Reference ... - Freescale

E—Enable
0 = Transparent translation/access control disabled
1 = Transparent translation/access control enabled
CI—Cache Inhibit
0 = Caching allowed
1 = Caching inhibited
R/W—Read/Write
0 = Only write accesses permitted
1 = Only read accesses permitted
R/WM—Read/Write Mask
0 = R/W field used
1 = R/W field ignored
MOTOROLA
M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL
Introduction
FC BASE—Function Code Base
This 3-bit field defines the base function code for accesses to be transparently translated
with this register. Addresses with function codes that match the FC BASE field (and are
otherwise eligible) are transparently translated.
FC MASK—Function Code Mask
This 3-bit field contains a mask for the FC BASE field. Setting a bit in this field causes
the corresponding bit of the FC BASE field to be ignored.
1.3.6.2 TRANSPARENT TRANSLATION/ACCESS CONTROL REGISTER FIELDS FOR
THE M68040. Figure 1-10 illustrates the MC68040 and MC68LC040 transparent
translation/ MC68EC040 access control register format.
31 24 23 16
ADDRESS BASE ADDRESS MASK
E S FIELD 0 0 0 U1 U0 0 CM 0 0 W 0 0
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Figure 1-10. MC68040 and MC68LC040 Transparent Translation/MC68EC040 Access
Control Register Format
Address Base
This 8-bit field is compared with address bits A31 – A24. Addresses that match in this
comparison (and are otherwise eligible) are transparently translated/access controlled.
1-13