UPD75238GJ NEC [NEC], UPD75238GJ Datasheet - Page 139
UPD75238GJ
Manufacturer Part Number
UPD75238GJ
Description
4 BIT SINGLE-CHIP MICROCOMPUTER
Manufacturer
NEC [NEC]
Datasheet
1.UPD75238GJ.pdf
(190 pages)
- Current page: 139 of 190
- Download datasheet (2Mb)
5.4 MULTIPLE INTERRUPT PROCESSING CONTROL
(1) Multiple interrupt processing by a high-order interrupt
IST1
The PD75238 can handle multiple interrupts by either of the following methods.
0
0
1
1
In this method, the PD75238 selects an interrupt source among multiple interrupt sources, enabling
double interrupt processing.
That is, the high-order interrupt specified by the interrupt priority specification register (IPS) is enabled
when the processing status is 0 or 1. Other interrupts (interrupts lower than the specified high-order
interrupt) are enabled only when the status is 0. (See Fig. 5-6 and Table 5-3.)
IST1 and IST0 are saved with the remaining PSW in the stack memory when an interrupt is accepted and
the status of IST0 and IST1 changes to a status one level higher. When an RETI instruction is executed,
the former values of IST0 and IST1 are returned.
IST0
0
1
0
1
Interrupt is disabled.
Low- or high-order
interrupt occurrence
Interrupt is enabled.
Status 0
Status 1
Status 2
This status is disabled.
Processing
status
Fig. 5-6 Multiple Interrupt Processing by a High-Order Interrupt
IPS setting
Table 5-3 Interrupt Processing Statuses of IST1 and IST0
Is processing the normal
program.
Is processing a low- or high-
order interrupt.
Is processing a high-order
interrupt.
Normal
processing
(Status 0)
CPU operation
High-order
interrupt
occurrence
Low- or high-order
interrupt processing
(Status 1)
All
Only high-order interrupts
None
Interrupts that can be accepted
High-order
interrupt
processing
(Status 2)
After acceptance
PD75238
IST1
0
1
–
IST0
1
0
–
139
Related parts for UPD75238GJ
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
The high-density rack server NEC Express5800/R120d-1E
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
The high-density rack server NEC Express5800/R120d-1M
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
The flexible compact rack server NEC Express5800/R120d-2E
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
The high-capacity rack server NEC Express5800/R120d-2E(Storage-Rich)
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
The scalable compact rack server NEC Express5800/R120d-2M
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
The flexible blade server NEC Express5800/B120d
Manufacturer:
NEC [NEC]
Datasheet:
Part Number:
Description:
16/8 bit single-chip microcomputer
Manufacturer:
NEC
Datasheet:
Part Number:
Description:
Dual audio power amp circuit
Manufacturer:
NEC
Datasheet:
Part Number:
Description:
Dual comparator
Manufacturer:
NEC
Datasheet:
Part Number:
Description:
MOS type composite field effect transistor
Manufacturer:
NEC
Datasheet:
Part Number:
Description:
50 V/100 mA FET array incorporating 2 N-ch MOSFETs
Manufacturer:
NEC
Datasheet: