CMOS内存信息
2008-10-24 20:05
155 查看
The CMOS memory informationCMOS stands for: Complementary Metal Oxide SemiconductorIn the 286 and up, the CMOS memory chip holds 64 bytes of data. The data is held in the chip by the battery. This is so that when you turn your machine off, the machine can still keep track of the time, data, disk type(s) and so one. The CMOS memory is accessed via 2 I/O ports, at addresses 70h and 71h. A program writes the config. address (00h through 3Fh) to I/O port 70h and then writes a new byte value or reads the current byte value at I/O port 71h. I strongly suggest that you don't write to these ports unless you know what you are doing. You could severely mess up your machine The following table specifies the information in the CMOS memory: address (hex) Contents 00h Current Second (either in BCD or hex format, see bit 2 of offset 0Bh below) 01h Second Alarm 02h Current Minute 03h Minute Alarm 04h Current Hour (see bit 1 of offset OBh below) 05h Hour Alarm 06h Day of the Week 07h Day of the Month 08h Month 09h Year (00-99) (see offset 32h) 0Ah Clock Register A 0Bh Clock Register B bits: 76543210 Meaning X....... 1 = enable clock setting by freezing updates .X...... 1 = enable periodic interrupt ..X..... 1 = enable alarm interrupt ...X.... 1 = enable update-ended interrupt ....X... 1 = enable square wave output .....X.. 1 = Data Mode - 0: BCD, 1: Binary ......X. 1 = 24/12 hour selection - 1 enables 24 hour mode .......X 1 = Daylight Savings Enable =1 enables automatic switching to/from DST in April and October 0Ch Clock Register C 0Dh Clock Register D 0Eh Diagnostic byte (got during Power On Self Test) bits: 76543210 Meaning X....... 1 = CMOS battery Dead .X...... 1 = checksum incorrect ..X..... 1 = config. byte incorrect ...X.... 1 = memory size incorrect ....X... 1 = hard disk or controller error .....X.. 1 = date or time incorrect ......XX Not used 0Fh Power-down system status ?what was last boot? 10h Bits 4-7: first floppy disk type 0000 = no disk drive 0001 = 5.25" 320k or 360k 0010 = 5.25" 1.2m 0011 = 3.5" 720k 0100 = 3.5" 1.44m 0110 = 3.5" 2.88m Bits 0-3: second floppy disk type same as above 11h reserved 12h Bits 4-7: first Hard Drive type Bits 3-0: second Hard Drive type 13h reserved 14h Configuration byte bits: 76543210 Function Meaning XX...... number of disk drives 00 = 1 drive 01 = 2 drives ..XX.... Primary display type 00 = display has its own BIOS 01 = 40-column CGA 10 = 80-column CGA 11 = MDA ....XX.. not used ......X. 1 = math coprocessor installed ......X. 0 = no floppy drives 1 = floppy drives available 15h Low byte of base memory size 100h = 256k 200h = 512k 280h = 640k 16h High byte of 15h above 17h Low expansion memory byte 18h High expansion memory byte 200h = 512k 400h = 1024k 600h-3C00h = 1536-15,360k 19h Extended type byte: Hard drive 1 1Ah Extended type byte: Hard drive 2 1Bh-2Dh reserved 2Eh check-sum for addresses 10h-2Dh (word) 2Fh see above 30h Low expansion memory byte 31h High expansion memory byte 200h = 512k 400h = 1024k 600h-3C00h = 1536-15,360k 32h Centry in BCD (19 or 20) (see offset 09h) 33h Information flag You may also use INT 11h to get some of this data. For more detailed information, download the following zip file: CMOSINFO.ZIP For a sample assembler program to print the date and time, download the following asm file: cmosdt.asm (3k) This was extracted from Peter Norton's PC Programmers Bible 本文转自http://www.frontiernet.net/~fys/cmosinfo.htm |
相关文章推荐
- Shell采集系统cpu 内存 磁盘 网络信息
- linux查看主板内存槽与内存信息的命令dmidecode方法
- Android 笔记记录(1)去掉虚拟键盘、获取内存使用信息
- java监控linux服务器CPU,内存等信息
- shell采集系统cpu 内存 磁盘 网络信息
- CentOS查看CPU、内存、版本等系统信息
- Android获取系统cpu信息,内存,版本,电量等信息
- java获取cpu、内存、硬盘信息
- Android中获取系统内存信息以及进程信息-----ActivityManager的使用(一)
- 打印对战内存异常信息到日志中
- 一个Window/Linux(Fedora测试平台)的CPU,磁盘,内存,PC,进程相关信息采集功能
- linux 下查看主板、CPU、内存、硬盘等信息
- Python 如何获取Android应用内存使用和CPU占用信息,并且时时展示曲线图形。
- Linux 查看内核,CPU,内存信息命令
- Linux下查看操作系统信息、内存情况及cpu信息:cpu个数、核心数、线程数
- Linux命令(24):free命令-显示内存信息
- Linux 查看CPU信息,机器型号,内存等信息
- 获取硬盘大小.内存.cpu信息
- Oracle内存结构:Shared Pool的详细信息
- 获取操作系统CPU及内存使用信息的另一种方法