Return Styles: Pseud0ch, Terminal, Valhalla, NES, Geocities, Blue Moon. Entire thread

Boot sector question

Name: Anonymous 2008-08-26 20:13

I have a floppy disk that boots MS-DOS and executes some commands.

The last command I want it to run is something that loads the hard disk boot sector in and jumps to it, thus relinquishing control from DOS.

My code is:

mov ax, 201h
mov bx, 7c00h
xor cx, cx
mov es, cx
inc cx
mov dx, 80h
int 13h
jmp 0:7c00h

but this just hangs. Any ideas what could be going wrong?

Name: Anonymous 2008-08-26 20:38

Check cf/ah for the status/return code. How many hard drives do you have? Perhaps the first disk is a GUID Partition Table disk?

Name: Anonymous 2008-08-26 21:02

Write boot record code in Java

Name: Anonymous 2008-08-26 21:07

Read SICP.

Name: Anonymous 2008-08-26 21:47

I dunno, ask Xarn.

Name: Anonymous 2008-08-26 21:50

>>2
Thanks for your suggestions. However I've narrowed the bug down to when the Windows-installed boot sector copies itself from 0x7C00 to 0x600. It appears to overwrite some DOS structures which causes the system to hang. I expect DOS has hooked some of the BIOS interrupts so the boot sector code ends up calling it instead of the BIOS. Not sure yet though.

Name: Anonymous 2008-08-26 21:54

>>6
The first thing that comes to mind is the timer interrupt (0x1C).

Name: Anonymous 2008-08-27 2:30

cli ?

Name: Anonymous 2008-08-27 9:32

LOCK CMPXCHG8B EAX?

Name: Anonymous 2008-08-27 10:41

HAX GOAT PTR [ANUS]?

Name: Anonymous 2009-03-06 8:13


The SJIS cat is   a cdt and   he can tune   a file system   found on device   lde seek block.

Name: Anonymous 2009-08-16 22:58

Lain.

Name: Anonymous 2013-01-19 14:39

/prog/ will be spammed continuously until further notice. we apologize for any inconvenience this may cause.

Newer Posts
Don't change these.
Name: Email:
Entire Thread Thread List