插上MICRO跳线帽（就是那个决定从NAND还是NOR启动的跳线地方）后，一上电总是进入BIOS，信息如下：
+---------------------------------------------+
| S3C2440A USB Downloader ver R0.03 2004 Jan |
+---------------------------------------------+
USB: IN_ENDPOINT:1 OUT_ENDPOINT:3
FORMAT: <ADDR(DATA):4>+<SIZE(n+10):4>+<DATA:n>+<CS:2>
NOTE: Power off/on or press the reset button for 1 sec
in order to get a valid USB device address.
NAND device: Manufacture ID: 0xec, Chip ID: 0xda (Samsung K9F2G08U0B)
Could not found stored vivi parameters. Use default vivi parameters.
##### FriendlyARM BIOS 2.0 for 2440 #####
[x] format NAND FLASH for Linux
[v] Download vivi
[k] Download linux kernel
[y] Download root_yaffs image
[a] Absolute User Application
[n] Download Nboot for WinCE
[l] Download WinCE boot-logo
[w] Download WinCE NK.bin
[d] Download & Run
[z] Download zImage into RAM
[g] Boot linux from RAM
[f] Format the nand flash
Boot the system
[s] Set the boot parameters
Backup NAND Flash to HOST through USB(upload)
[r] Restore NAND Flash from HOST through USB
[q] Goto shell of vivi
Version: 0945-2K
Enter your selection:
接上串口输入b后能进linux系统
此时复位也可以进linux系统
但是上电的时候进不去系统，麻烦大家帮我分析下什么原因啊。。谢谢 
