Collection

zero Useful+1

zero

Addressing space

CPU's ability to address memory

The address space generally refers to the CPU's memory addressing Ability. Generally speaking, it is a question of how much memory can be used at most. Data in storage (RAM) storage is regular. When the CPU needs to extract data during operations, it needs to know where the data is stored. At this time, it needs to go door to door, which is called addressing. However, if there are too many addresses beyond the CPU's capacity, the CPU cannot find the data. The maximum range of addresses that the CPU can find is called addressing capability byte For example, a 32-bit addressed CPU can address an address of the 32nd power of 2, that is, 4G. This is why a 32-bit CPU can match 4G memory at most. No more CPUs can be found.

Chinese name: Addressing space
Foreign name: Addressing space
Meaning: CPU for memory addressing Ability of

Popular meaning: How much memory can be used at most
Addressing capability: What is the maximum range of addresses the CPU can find
Unit: byte

catalog

one brief introduction
two Port address assignment

brief introduction

Announce

edit

I/O port And addressing

CPU To access I/O interface For the data and status information on the controller or control card, their addresses need to be specified first. This address is called I/O Port address Or port for short. Usually, one I/O The controller contains data ports for accessing data, command ports for outputting commands, and access controllers Execution status Status port of. The port address can be set in two ways: Unified addressing and Independent addressing 。

The principle of unified port addressing is to classify the port address in the I/O controller into storage addressing address space Within the range. So this Addressing The mode is also called Storage image Addressing. The operation of accessing a port by the CPU is the same as the operation of accessing memory. It also uses the instruction of accessing memory. The method of port independent addressing is to treat the address space of I/O controller and control card as an independent address space, which is called I/O address Space. Each port has an I/O address corresponding to it, and uses a dedicated I/O Instructions To access the port.

IBM PC and its Compatible computer The independent addressing mode is mainly used, and an independent I/O address space is used to register Addresses and accesses. use ISA bus The I/O address space of traditional PC with structure is 0x000~0x3FF, with 1024 I/Os Port address available. See Table 2-1 for the port address range assigned and used by each controller and control card by default. The use and programming methods of these ports will be described in detail later when related hardware is involved.

In addition, IBM PC also partially uses Unified addressing Mode. For example, on the CGA display card display memory The address of Memory address The space is 0xB800~0xBC00. Therefore, if you want a character to be displayed on the screen, you can directly use memory operation instructions to write to this memory area.

Port address assignment

Announce

edit

Port address Range	Distribution description	Port address range	Distribution description
0x000～0x01F	8237A DMA controller one	0x1F0～0x1F7	IDE hard disk controller zero
0x020～0x03F	8259A Programmable Interrupt Controller one	0x278～0x27F	Parallel printer port 2
0x040～0x05F	8253/8254A timing counter	0x2F8～0x2FF	Serial controller 2
0x060～0x06F	eight thousand and forty-two Keyboard controller	0x378～0x37F	Parallel printer port 1
0x070～0x07F	Access the CMOS RAM/RTC (Real Time Clock) port	0x3B0～0x3BF	Monochrome MDA display controller
0x080～0x09F	DMA page register access port	0x3C0～0x3CF	Color CGA display controller
0x0A0～0x0BF	8259A Programmable Interrupt Controller two	0x3D0～0x3DF	Color EGA/VGA display controller
0x0C0～0x0DF	8237A DMA controller two	0x3F0～0x3F7	floppy disk controller
0x0F0～0x0FF	Coprocessor Access Port	0x3F8～0x3FF	Serial controller 1
0x170～0x177	IDE hard disk controller one	-	-

For using EISA or PCI, etc Bus structure Modern PC with 64KB I/O address The space is available for use. In a normal Linux system, you can view the/proc/ioports file to get the relevant controller or set the I/O address range used:

[ root@plinux root]# cat /proc/ioports

0000-001f : dma1

0020-003f : pic1

0040-005f : timer

0060-006f : keyboard

0070-007f : rtc

0080-008f : dma page reg

00a0-00bf : pic2

00c0-00df : dma2

00f0-00ff : fpu

0170-0177 : ide1

01f0-01f7 : ide0

02f8-02ff : serial(auto)

0376-0376 : ide1

03c0-03df : vga+

03f6-03f6 : ide0

03f8-03ff : serial(auto)

0500-051f : PCI device 8086:24d3 (Intel Corp.)

0cf8-0cff : PCI conf1

da00-daff : VIA Technologies, Inc. VT6102 [Rhine-II]

da00-daff : via-rhine

e000-e01f : PCI device 8086:24d4 (Intel Corp.)

e000-e01f : usb-uhci

e100-e11f : PCI device 8086:24d7 (Intel Corp.)

e100-e11f : usb-uhci

e200-e21f : PCI device 8086:24de (Intel Corp.)

e200-e21f : usb-uhci

e300-e31f : PCI device 8086:24d2 (Intel Corp.)

e300-e31f : usb-uhci

f000-f00f : PCI device 8086:24db (Intel Corp.)

f000-f007 : ide0

f008-f00f : ide1

[ root@plinux root]#^[1]

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001