4

IP2 Chip

ADR/SIZ

 

 

 

$FFFBC001 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

7

6

5

 

4

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

NAME

REV7

REV6

REV5

 

REV4

REV3

 

REV2

REV1

REV0

 

 

 

 

 

 

 

 

 

 

 

OPER

R

R

R

 

R

R

 

R

R

R

 

 

 

 

 

 

 

 

 

 

 

RESET

0

0

0

 

0

0

 

0

0

1

 

 

 

 

 

 

 

 

 

 

 

Vector Base Register

ADR/SIZ

 

 

 

$FFFBC003 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

7

6

5

 

4

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

NAME

IV7

IV6

IV5

 

IV4

IV3

 

IV2

IV1

IV0

 

 

 

 

 

 

 

 

 

 

 

OPER

R/W

R/W

R/W

 

R/W

R/W

 

R

R

R

 

 

 

 

 

 

 

 

 

 

 

RESET

0

0

0

 

0

1

 

1

1

1

 

 

 

 

 

 

 

 

 

 

 

The interrupt Vector Base Register is an 8-bit read/write register that is used to supply the vector to the CPU during an interrupt acknowledge cycle for the four DMA controller interrupts and for the programmable clock interrupt. Only the most significant five bits are used. The least significant three bits encode the interrupt source during the acknowledge cycle. The exception to this is that after reset occurs, the interrupt vector passed is $07, which remains in effect until a write is generated to the Vector Base Register.

Note Note that this register does not affect the vector supplied during an interrupt acknowledge cycle for any of the eight IndustryPack IRQ*s.

For some versions of the IP2 chip, this register is write only.

! There is NO known workaround for this error. This register

Caution does return the correct value for the interrupt acknowledge cycle.

4-18

Computer Group Literature Center Web Site

Page 254
Image 254
Motorola MVME172 manual Vector Base Register