Subject: Bootstrap floppies on i386
To: None <current-users@NetBSD.ORG>
From: Dave Hanna <>
List: current-users
Date: 07/18/1995 22:56:43
I'm trying to get an installation up on an i386.

I've read the installation notes and have ftp'd the bootstrap file
system images to my machine, and used rawrite to transfer them to

The problem is that what is written in sector 0 of the floppy is NOT
what is in the first 512 bytes of the filesystem image.

Specifically, bytes 0 and 1, and bytes (hex) 1e through 1bd are the
MSDOS bootstrap.  Bytes 2 through 1d and 1be through 1ff are the correct
NetBSD bootstrap code.

I've run rawrite under a PC-DEBUGGER, and verified the data just before
the biosdisk call that writes it, and it is correct.  It just never shows
up on the disk.

I'm theorizing that there is some anti-virus code in the BIOS that prevents
the MSDOS bootstrap executeable from being written with anything else.
Does anyone know if this is, in fact, true, and if so, is there a way around
it?  (I couldn't find any CMOS configuration settings that might turn it

Also, does the MSDOS Write Absolute call (INT 26H) use the BIOS call, or
does it manipulate the hardware directly?

Any help would be appreciated.  Thanks.

        Dave Hanna
        Infotouch Systems, Inc.