參數(shù)資料
型號： 20736
英文描述： Enhanced Am486DX Family Data Sheet? 1.87MB (PDF)
中文描述： 增強Am486DX系列數(shù)據(jù)手冊？ 1.87MB（PDF格式）
文件頁數(shù)： 39/66頁
文件大小： 1923K
代理商： 20736
Enhanced Am486DX Microprocessor Family
39
P R E L I M I N A R Y
I
SMI:
System Management Interrupt. This is the trig-
ger mechanism for the SMM interface. When SMI is
asserted (SMI pin asserted Low) it causes the pro-
cessor to invoke SMM. The SMI pin is the only
means of entering SMM.
I
SMI handler:
System Management mode handler.
This is the code that is executed when the processor
is in SMM. Example applications that this code might
implement are a power management control or a
system control function.
I
RSM:
Resume instruction. This instruction is used
by the SMI handler to exit the SMM and return to the
interrupted OS or application process.
I
SMRAM:
This is the physical memory dedicated to
SMM. The SMI handler code and related data reside
in this memory. The processor also uses this mem-
ory to store its context before executing the SMI han-
dler. The operating system and applications should
not have access to this memory space.
I
SMBASE:
This is a control register that contains the
base address that defines the SMRAM space.
I
Context:
This term refers to the processor state. The
SMM discussion refers to the context, or processor
state, just before the processor invokes SMM. The
context normally consists of the CPU registers that
fully represent the processor state.
I
Context Switch:
A context switch is the process of
either saving or restoring the context. The SMM dis-
cussion refers to the context switch as the process
of saving/restoring the context while invoking/exiting
SMM, respectively.
I
SMSAVE:
A mechanism that saves and restores all
internal registers to and from SMRAM.
6.3
System Management Interrupt
Processing
The system interrupts the normal program execution
and invokes SMM by generating a System Management
Interrupt (SMI) to the CPU. The CPU services the SMI
by executing the following sequence (see Figure 22).
1.
The CPU asserts the SMIACT signal, instructing the
system to enable the SMRAM.
The CPU saves its state (internal register) to SM-
RAM. It starts at the SMBASE relative address lo-
cation (see Section 7.3.3), and proceeds downward
in a stack-like fashion.
The CPU switches to the SMM processor environ-
ment (an external pseudo-real mode).
The CPU then jumps to the absolute address of
SMBASE + 8000h in SMRAM to execute the SMI
handler. This SMI handler performs the system
management activities.
Note:
If the SMRAM shares the same physical address
location with part of the system RAM, it is “overlaid”
SMRAM. To preserve cache consistency and correct
SMM operation in systems using overlaid SMRAM, the
cache must be flushed via the FLUSH pin when entering
SMM.
2.
3.
4.
5.
The SMI handler then executes the RSM instruction
which restores the CPU’s context from SMRAM,
deasserts the SMIACT signal, and then returns con-
trol to the previously interrupted program execution.
For uses such as fast enabling of external I/O devices,
the SMSAVE mode permits the restarting of the I/O in-
structions and the HALT instruction. This is accom-
plished through I/O Trap Restart and Halt/Auto HALT
Restart slots. Only I/O and HALT opcodes are restart-
able. Attempts to restart any other opcode may result
in unpredictable behavior.
The System Management Interrupt hardware interface
consists of the SMI request input and the SMIACT output
used by the system to decode the SMRAM (see Figure
23).
SMI
#1
#2
#3
Instr
Instr
Instr
State Save
SMI Handler
State Restore
#4
#5
Instr
Instr
SMI
SMIACT
Figure 22. Basic SMI Interrupt Service
RSM
相關PDF資料
PDF描述
2075 data delay devices
208-501-21-38 LED TELEFONSOCKEL T6.8 12V ROT
208-521-21-38 LED TELEFONSOCKEL T6.8 12V GELB
208-532-21-38 LED TELEFONSOCKEL T6.8 12V GRUEN
208-930-21-38 LED TELEFONSOCKEL T6.8 12V BLAU
相關代理商/技術參數(shù)
參數(shù)描述
207360-1 功能描述:管腳和插座連接器 3P PLUG HOUSING RoHS:否 制造商:Molex 系列:1561 產(chǎn)品類型:Contacts 觸點類型:Socket (Female) 節(jié)距: 位置/觸點數(shù)量: 排數(shù): 安裝風格:Wire 端接類型:Crimp 外殼材料: 觸點材料:Brass 觸點電鍍:Tin 電壓額定值: 電流額定值:
20-7360-10 功能描述:IC 與器件插座 ELEVATOR STRIP LINE 20 PINS RoHS:否 制造商:Molex 產(chǎn)品:LGA Sockets 節(jié)距:1.02 mm 排數(shù): 位置/觸點數(shù)量:2011 觸點電鍍:Gold 安裝風格:SMD/SMT 端接類型:Solder 插座/封裝類型:LGA 2011 工作溫度范圍:- 40 C to + 100 C
207363-000 制造商:TE Connectivity 功能描述:MTC50-YH2-004
207365-1 功能描述:管腳和插座連接器 PIN HDR ASSY METRIMATE 3P RoHS:否 制造商:Molex 系列:1561 產(chǎn)品類型:Contacts 觸點類型:Socket (Female) 節(jié)距: 位置/觸點數(shù)量: 排數(shù): 安裝風格:Wire 端接類型:Crimp 外殼材料: 觸點材料:Brass 觸點電鍍:Tin 電壓額定值: 電流額定值:
207365-3 功能描述:管腳和插座連接器 PIN HEADER 3P RoHS:否 制造商:Molex 系列:1561 產(chǎn)品類型:Contacts 觸點類型:Socket (Female) 節(jié)距: 位置/觸點數(shù)量: 排數(shù): 安裝風格:Wire 端接類型:Crimp 外殼材料: 觸點材料:Brass 觸點電鍍:Tin 電壓額定值: 電流額定值:
發(fā)布緊急采購，3分鐘左右您將得到回復。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*