Motorola MC68VZ328 - Manual (Page 106)

6-18 MC68VZ328 User’s Manual
Programming Model
The unprotected memory size is calculated according to the chip-select addressing space and the UPSIZ
value.
Example 6-1. Unprotected Memory Size Calculation
For example, if SIZ[2:0] in CSD = 111 and UPSIZ[2:0] = 011, the unprotected size is calculated as
follows:
4 Mbyte / 2
(7-3)
= 256K
6.3.6 Chip-Select Control Register 2
This register controls early cycle detection for both static and dynamic types of memory. It improves CPU
access performance by generally removing one CPU wait state or by relaxing the timing requirement for
the memory.
CSCTRL2 Chip-Select Control Register 2 0x(FF)FFF10C
Reserved
Bit 3 Reserved This bit is reserved and should be set to 0.
CUPS2
Bit 2 UPSIZ Bit 2 CSC Register—This is the most
significant bit for UPSIZ[2:0] when the EUPEN
bit is set. For information on calculating unprotected
memory size, see Example 6-1.
Reserved
Bit 1 Reserved This bit is reserved and should be set to 0.
BUPS2
Bit 0 UPSIZ Bit 2 CSB Register—This is the most
significant bit for UPSIZ[2:0] when the EUPEN
bit is set. For information on calculating unprotected
memory size, see Example 6-1.
BIT 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 BIT 0
ECDD ECDS ECDT EASP EASDLY[1:0]
TYPE rw rw rw rw rw rw
RESET
0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0
0x1000
Table 6-13. Chip-Select Control Register 2 Description
Name Description Setting
ECDD
Bit 15 Early Cycle Detection for Dynamic
Memory—This bit advances the timing, allow-
ing the CPU to be used with dynamic memory
access. It reduces wait states by one. 0 = Disabled.
1 = Enabled.
Table 6-12. Chip-Select Control Register 1 Description (Continued)
Name Description Setting
Unprotected Size
Chip-Select Size
2
7 UPSIZ –
( )
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