problem with grub configuration

[Janet Anstett]

I have a problem with the grub configuration on my machine.  I have
RedHat 7.2 installed on a Dell Precision 410 machine.  I am trying to
set the amount of memory in the boot command.  All of the stuff that I have
seen says to put mem=256M at the end of the boot command.  This
will not work on this particular machine.  I tried to do this on
another machine and the machine boots fine.  One difference between
the two machines is the one that works has IDE drives and the one that
doesn't work has SCSI drives.  

version: grub-0.90-11 which was installed with the RedHat 7.2
installation.

This is my grub.conf file:

default=0
timeout=10
splashimage=(hd0,0)/boot/grub/splash.xpm.gz
title Red Hat Linux (2.4.7-10smp)
        root (hd0,0)
        kernel /boot/vmlinuz-2.4.7-10smp ro root=/dev/sda1 mem=254M
        initrd /boot/initrd-2.4.7-10smp.img
title Red Hat Linux-up (2.4.7-10)
        root (hd0,0)
        kernel /boot/vmlinuz-2.4.7-10 ro root=/dev/sda1
        initrd /boot/initrd-2.4.7-10.img

This is the error I get when I try to boot the system with the smp
configuration:

request_module[block-major-8]: Root fs not mounted
VFS: Cannot open root device "sda1" or 8:01
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 08:01

disk partition map:

Disk /dev/sda: 255 heads, 63 sectors, 2213 cylinders
Units = cylinders of 16065 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sda1   *         1       637   5116671   83  Linux
/dev/sda2           638      1019   3068415   83  Linux
/dev/sda3          1020      1149   1044225   82  Linux swap
/dev/sda4          1150      2213   8546580    f  Win95 Ext'd (LBA)
/dev/sda5          1150      2213   8546548+  83  Linux

Without the mem=254M, the system boots fine with the smp
configuration.  I am trying to use a
motion video card in my machine that requires some memory for the
card.  Therefore, I have to specify a mem that is 2M less what the
system has in order to save that 2M for the motion video card.

Thank you,
Janet Anstett