Chapter 4 System Support
4.4
s
ded on a priority
4.4.1 I U
The microprocessor uses tw ware interrupts; maskable and nonmaskable. A
m kable interr be e disabled within the microprocessor by the use of the STI and
C instructions. A nonma annot be masked off within the microprocessor,
a ugh it may ibited or software means external to the microprocessor.
4.4.1.1 askab erru
The maskable i t is a l used by peripheral functions within the
s to get th ion o eripheral functions produce a unique INTA-H
( Q0-15 (ISA) sig asserts the interrupt
e microprocessor. The microprocessor halts execution to determine the source
of the in vices the peripheral as appropriate.
the routing of PCI and ISA interrupts. Most IRQs are routed through the I/O
Figure 4-9. M ble In Processing, Block D gram
Interrupts may be roce o o ( bl gh th 10 Se uti
♦ 825
♦ API
SYSTEM RESOURCES
This section describes the availability and basic control of major subsystems, otherwise known a
resource allocation or simply “system resources.” System resources are provi
nts. basis through hardware interrupts and DMA requests and gra
NTERR PTS
o types of hard
as upt can nabled or
LI skable interrupt c
ltho be inh by hardware
M le Int pts
nterrup hardware-generated signa
ystem e attent f the microprocessor. P
PCI) or IR nal that is routed to interrupt processing logic that
(INTR-) input to th
terrupt and then ser
igure 4-9 showsF
controller, which contains a serializing function. A serialized interrupt stream is applied to the
82801 ICH2.
IRQ3..7,
I/O Cntlr.
9..12,
14,15
Interrup
aska terrupt ia
p sse ind ne tw of m esod sel taec e th our e F tup lity):
INTA-..H-
9 mode
C mode
82801
ICH2
Interrupt
IRQ14,15
IDE
Hard Drives
INTR-
Processing
Serial IRQ
I/O &
SM Functions
Serializer
Processor
PCI Peripherals
LPC47B367
t
APIC bus
Compaq Evo and Workstation Personal Computers
Featuring the Intel Pentium 4 Processor
Second Edition – January 2003
4-16
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