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Rabbit 3000 Microprocessor User’s Manual
MMU Expanded Code Register
(MECR)
(Address = 0x0018)
Bit(s)
Value
Description
7:3
These bits are reserved and should be written with zeros. Read returns zeros.
2:0
000
Normal operation.
001
This bit combination is reserved and should not be used.
010
This bit combination is reserved and should not be used.
011
This bit combination is reserved and should not be used.
100
For an XPC access, use MB0CR independent of bank select address.
101
For an XPC access, use MB1CR independent of bank select address.
110
For an XPC access, use MB2CR independent of bank select address.
111
For an XPC access, use MB3CR independent of bank select address.
Memory Timing Control Register
(MTCR)
(Address = 0x0019)
Bit(s)
Value
Description
7:4
These bits are reserved and should be written with zeros.
3
0
Normal timing for /OE1 (rising edge to rising edge, one clock minimum).
1
Extended timing for /OE1 (one-half clock earlier than normal).
2
0
Normal timing for /OE0 (rising edge to rising edge, one clock minimum).
1
Extended timing for /OE0 (one-half clock earlier than normal).
10
Normal timing for /WE1 (rising edge to falling edge, one and one-half clocks
minimum).
1
Extended timing for /WE1 (falling edge to falling edge, two clocks minimum).
00
Normal timing for /WE0 (rising edge to falling edge, one and one-half clocks
minimum).
1
Extended timing for /WE0 (falling edge to falling edge, two clocks minimum).
Write Protection Control Register
(WPCR)
(Address = 0x0440)
Bit(s)
Value
Description
7:1
These bits are reserved and should be written with zeros.
0
Write protection in User Mode only.
1
Write protection in System and User modes.