
7.6 Extended intelligent I/O service (EI2OS)
MB90580 Series
Chapter 7: Interrupt
91
7.6.2 Structure
EI
2
OS is handled by the following four sections:
Internal resources.................. Interrupt enable and request bits: Used to control interrupt requests
from resources.
Interrupt controller
ICR:Assigns interrupt levels, determines the priority levels
of simultaneously requested interrupts, and selects the
EI
2
OS operation.
CPU ....................................... I and ILM:Used to compare the requested and current interrupt
levels and to identify the interrupt enable status.
Microcode:E
2
OS processing step
RAM....................................... Descriptor:Describes the EI
2
OS transfer information.
Each register is described below.
(1) Interrupt control register (ICR)
The interrupt control register is in the interrupt controller. This register corresponds to I/Os that have the
interrupt function. This register has the following three functions:
Sets the interrupt level of the corresponding peripheral.
Selects whether to handle the interrupt of the corresponding peripheral as an ordinary interrupt or as
an extended intelligent I/O service.
Selects the extended intelligent I/O service channel.
Do not access this register by a read-modify-write instruction, as doing so causes misoperation.
Interrupt control register (ICR)
Note:
ICS3 to ICS0 are valid only when EI
2
OS is activated. Set ISE to ’1’ to activate
EI
2
OS, and to ’0’ not to activate it. When EI2OS is not to be activated, any value
can be written to ICS3 to ICS0.
* ’1’ is always read.
ICS1 and ICS0 are valid for write only. S1 and S0 are valid for read only.
ICS3
ICS2
ICS1
ICS0
ISE
IL2
IL1
IL0
15/7
14/6
13/5
12/4
11/3
10/2
9/1
8/0
when written
Address : B0
H
–BF
H
(W)
(0)
(W)
(0)
(W)
(0)
(W)
(0)
(W)
0)
(W)
(1)
(W)
(1)
(W)
(1)
Read/write
Initial value
Bit number
—
—
S1
S0
ISE
IL2
IL1
IL0
15/7
14/6
13/5
12/4
11/3
10/2
9/1
8/0
when read
Address : B0
H
–BF
H
(–)
(X)
(–)
(X)
(R)
(0)
(R)
(0)
(R)
0)
(R)
(1)
(R)
(1)
(R)
(1)
Read/write
Initial value
Bit number