bochs窗口显示“fatal:no bootable device.”

我在bochs官网下载个freedos，解压后把a.img改名为freedos，且自己创建了一个软盘叫pm.img，bochs配置文件如下：
megs: 32
romimage: file=../BIOS-bochs-latest
vgaromimage: file=../VGABIOS-lgpl-latest
floppya: 1_44=freedos.img, status=inserted
floppya: 1_44=pm.img, status=inserted
boot: a
log: bochsout.txt
mouse: enabled=0

freedos.img和pm.img和bochs配置文件都放在同一个文件夹下。双击配置文件运行bochs却显示一个小的windows窗口如下：
panic
device
message=no bootable device.
continue ok
continue and don't ask again
kill simulation
abort(dump core) cancel

bochs黑色窗口里的最后几行显示如下：
booting from floppy...
boot from floppy failed:not a bootable disk
fatal:no bootable device.


请问怎样解决，我就是想用bochs运行我的磁盘dos(freedos.img)。

floppya: 1_44=freedos.img, status=inserted
floppya: 1_44=pm.img, status=inserted
两个都是A盘？