Coprocessors

5.2.2Register 1 – Control

Register 1 is a read/write register containing control bits. All writable bits in this register are forced low by reset. The shaded bits (also labeled r) are reserved and are not readable or writable.

3113 129 8 7 6 5 4 3 2 1 0

r r r r r r r r r r r r r r r r r r X I r r R S B 1 1 1 W C A M

M bit 0

Enable/disable

 

0

On-chip memory-management unit disabled

 

1

On-chip memory-management unit enabled

A bit 1

Address fault enable/disable

 

0

Alignment fault disabled

 

1

Alignment fault enabled

C bit 2

Data cache enable/disable

 

0

– Data cache disabled

 

1

– Data cache enabled

W bit 3

Write buffer enable/disable

 

0

– Write buffer disabled

 

1

– Write buffer enabled

B bit 7

Big/little endian

 

0

– Little endian operation

 

1

– Big endian operation

S bit 8

System

 

This bit selects the access checks performed by the memory-management unit.

 

See the ARM Architecture Reference for more information.

R bit 9

ROM

 

This bit selects the access checks performed by the memory-management unit.

 

See the ARM Architecture Reference for more information.

I bit 12

Instruction cache enable/disable

 

0

– Instruction cache disabled

 

1

– Instruction cache enabled

X bit 13

Virtual interrupt vector adjust

 

0

– Base address of interrupt vectors is 0h0000 0000

 

1

– Base address of interrupt vectors is 0hFFFF 0000

Bits 14..31

Unused.

 

Undefined on Read. Writes ignored.

SA-1100 Developer’s Manual

5-3

Page 47
Image 47
Intel SA-1100 manual Register 1 Control