.TH USAGE 8
.SH NAME
usage \- installing and using Minix
.SH DESCRIPTION
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This manual page describes the installation and use of Minix from a
System Administrators point of view.  It contains an installation guide,
instructions on how to do the initial configuration and some other info.
Other detailed information can be found in
.BR boot (8)
and
.BR hier (7).
.SS Requirements
The minimum system Minix can be installed on comfortably is an IBM PC/AT
or PS/2 with a 286 processor, 2 Mb memory, a 720 kb diskette drive, and 30
Mb free space on an AT,
.ig
PS/2,
..
ESDI, or SCSI hard disk (the latter controlled by an Adaptec 1540.)  Minix
for the 386 (Minix-386 for short) can be installed on a machine with at
least a 386sx processor and 3 Mb memory.
.SS Installation
You can install Minix automatically or manually as described in the sections
below.  The end result is the same, but manual installation allows
one to deviate from the preconfigured choices.  You may wish to read the
manual pages of the programs used below before you start.  You may especially
want to read
.BR boot (8)
if your machine is not a standard AT clone, because you may need to set a
few boot parameters to configure drivers.  To do this type
.B ESC
to get to the Boot Monitor prompt, set the appropriate variables, use
.B save
to store the settings and
.B menu
to continue where you left off.
.PP
To install the system you need two diskettes: a bootable root diskette and a
diskette full of binaries to use as
.BR /usr .
Let's call these diskettes
.B \s-2ROOT\s+2
and
.BR \s-2USR\s+2 .
These two diskettes may also be combined on a single high density diskette.
In that case the \s-2USR\s+2 part is on the
.B c
partition.
.PP
Insert the \s-2ROOT\s+2 diskette, boot the machine and type '=' to the menu.
The Minix kernel is loaded and takes control when you see the copyright
banner.  After loading the root diskette into the RAM disk you will be asked
to finish the name of the device to mount on
.BR /usr .
Remove \s-2ROOT\s+2, insert \s-2USR\s+2 and answer the question with
.BR fd0 ,
the name of floppy disk 0, or
.BR fd0c
for a combined diskette.  Login as
.BR root .
.SS "Automatic Installation"
Type
.B instdist
to start the installation script.  
The first thing to do is to make a partition, for this you are placed in a
partition table editor named
.BR part .
This partition table editor is very easy to use (in the author's opinion),
but it is also very easy to make a mess of your partition table real quick.
So if you get into trouble, type 'q' to quit, 'n' to not write the table, DEL
to stop the installation script and start over.  Use the '?' key to get
help.
.PP
With the '+' and '\-' keys you can select the disk device to install on,
probably
.BR /dev/hd0 ,
the first hard disk.  The partition table will probably show a single MS-DOS
partition.  Do not touch it!  You only need to make one new partition, so
modify an entry marked "None".  Do not make the partition smaller than 20
Mb, and do not make it larger than 128 Mb (Minix-86) or 1 Gb (Minix-386).
The system needs 30 Mb in compiled state.
.PP
The script then wants to know the name of the partition you've created, this
name is probably still visible on the screen (hd2, hd6, something like
that.)  The new partition table is reloaded into the disk driver, and the
new Minix partition is carved up into two partitions, a 1440 kb root and
the rest for /usr.
.PP
After making /usr, it is immediately put to use to replace the installation
/usr file system so that you can remove the \s-2USR\s+2 diskette and insert
the \s-2ROOT\s+2 diskette (unless they are one and the same).  The root file
system is filled with the contents of the \s-2ROOT\s+2 diskette and slightly
patched up to work on the hard disk (/etc/fstab.)
.PP
To compute the size of the so-called "second level block cache" you are
asked to specify the memory size of your machine.
.PP
The last step is simple and boring.  You have to enter the
.BI USR. nn
floppies in the proper order to fill /usr completely.
.PP
You can now skip the next section, but it may be instructive to read it
anyway.
.SS "Manual Installation"
The instructions that follow are at a very low level and require you to be
very careful.  The big advantage is that you know precisely what
tools have been used and how everything works.  The disadvantage is that
you may easily make a mistake that either forces you to start over if you
are lucky, or wipes out the contents of your hard disk if you are not.
.PP
Run
.B part
to make partitions to load the system into.  The best thing to do is to make
one large primary partition and to carve this partition up into three
subpartitions for the root, a scratch partition, and a
.B /usr
partition.  The assumption is that you will use the second partition on the
first hard disk,
.BR /dev/hd2 ,
and that
.B hd2a
is the root subpartition and
.B hd2c
is /usr.  If you want to use the first partition on
the second hard disk for instance, then substitute hd6 and hd6[ac] for the
above.  On a \s-2SCSI\s+2 disk it will be /dev/sd2 for the second partition
on the disk at target 0.  See the section on devices below, and the manual
pages of
.BR part (8),
.BR hd (4),
and
.BR sd (4).
Start
.B part
and select the whole hard disk device (the "multiple of 5" device) that you
want to install Minix onto.  In our example it will be
.BR /dev/hd0 .
.PP
.B Part
is a bit dangerous to use, so be careful.  Only make a single partition in
the primary partition table, using an entry marked "None".  Then hit '>' on
this new partition to make a subpartition table.
.PP
For the root subpartition you are advised to use 1440 kb exactly.  You can
make it larger if you want to, but it is advisable never to let the contents
outgrow a floppy.  (The \s-2ROOT\s+2 diskette is a copy of a root file
system, and will be used to fill your root subpartition.)
.PP
The second subpartition is either empty or a "scratch" partition.  Minix no
longer uses the
.B b
subpartition for anything useful anymore, but it has become customary to
have root on
.B a
and /usr on
.BR c .
(You are free to ignore this convention, of course.)
.PP
Use the rest of the partition for the /usr
.B c
subpartition.
.PP
When you are done check that /dev/hd2a is active (the * after the partition
number) so you can boot from it later.
.PP
If your disk has bad blocks then don't put the root or scratch subpartition
on top of them.  Make sure the inode tables in the other partitions don't
have bad blocks either.  You can put the subpartitions out of order on the
disk if that helps.  Subpartition tables, other than the main partition
table, are not sorted by the driver.
.PP
After making the partitions you do not have to reboot.  The disk driver
reloads the partition tables on the next access if the disk is not in use.
(Open or mounted.)
.PP
To be able to boot from /dev/hd2a you must place a master bootstrap in
/dev/hd2.  It has been placed there by
.B part
if it told you that it was creating a new partition table, but
.PP
.XB "installboot\0\-m\0/dev/hd2\0/usr/mdec/masterboot"
.RE
.PP
will put it there for sure.
.PP
You will start by making a file system for /usr and filling it partially.
This may seem to be out of order, but you can't insert the \s-2ROOT\s+2
floppy right now.
.PP
.XB "mkfs\0/dev/hd2c"
.XB "readall\0\-b\0/dev/hd2c | sh"
.XB "mount\0/dev/hd2c\0/mnt"
.XB "cpdir\0\-v\0/usr\0/mnt"
.PP
This will create a file system on /dev/hd2c, mount it on /mnt, and copy the
contents of the \s-2USR\s+2 floppy onto it.  The call to
.B readall
marks bad blocks on the file system as unusable, you can omit this on a
drive known to be spotless (\s-2IDE\s+2 or \s-2SCSI\s+2.)
.PP
You can now use the new /usr in place of the \s-2USR\s+2 floppy:
.PP
.XB "umount\0/dev/hd2c"
.XB "umount\0/dev/fd0"
.XB "mount\0/dev/hd2c\0/usr"
.PP
This little dance has freed up your floppy drive, so please remove the
\s-2USR\s+2 diskette and replace it by the \s-2ROOT\s+2 diskette.  Make a
file system for the root with at least 512 inodes (files), and
fill it from the floppy:
.PP
.XB "mkfs\0\-i\0512\0/dev/hd2a"
.XB "mount\0/dev/fd0\0/fd0"
.XB "mount\0/dev/hd2a\0/mnt"
.XB "cpdir\0\-v\0/fd0\0/mnt"
.XB "umount\0/dev/fd0"
.PP
Edit the file
.B /mnt/etc/fstab
to name the new devices.  It should look like this:
.PP
.XB "root=/dev/hd2a"
.XB "usr=/dev/hd2c"
.PP
Unmount the new root:
.PP
.XB "umount\0/dev/hd2a"
.PP
Make it bootable:
.PP
.XB "installboot\0\-d\0/dev/hd2a\0/usr/mdec/bootblock\0boot"
.PP
The automatic script would now set the
.B rootdev
and
.B ramimagedev
boot variables.  You can do this now using the
.B edparams
command, but it is easier to postpone it until the testing phase.  The
settings should be:
.PP
.XB "rootdev=hd2a"
.XB "ramimagedev=hd2a"
.PP
All that is left to do is to fill /usr from the set of
.BI USR. nn
floppies:
.PP
.XB "cd\0/usr"
.XB "vol\0720\0/dev/fd0 | zcat | tar\0xvfp\0\-"
.PP
And insert all the floppies one by one in the proper order.  (The number 720
is the size of the images on floppy.  Replace by 1440 if you have combined
the the images two by two.)
.SS Testing
By now a new Minix system is present on your hard disk.  Time to see if
it works.  Leave the \s-2ROOT\s+2 diskette in the drive and type
.BR halt .
You are now going to use the power of the Boot Monitor on the diskette to
boot the Minix partition on the hard disk.  Use the monitor command
.B boot hd2
to boot the primary partition Minix has been installed in.  (It is "hd2" in
our example.)  For a \s-2SCSI\s+2 disk you will have to use a 'hd' name too.
The monitor uses the BIOS, so you will have to treat it as a "normal" disk
at this point.
.PP
The hard disk bootstrap is now showing the menu again.  You can type '='
to start Minix, but you probably want to change the boot parameters.
Hit
.B ESC
once more to get to the command prompt.  The command
.B set
shows what the current parameters are.  Here is an example that shows how
to make a menu to start Minix, start a test kernel, or boot MS-DOS:
.PP
.XB "minix(=,Minix)\0{boot}"
.XB "test(t,Test)\0{boot hd2b}"
.XB "dos(d,MS-DOS)\0{boot\0hd1}"
.XB "save"
.PP
MS-DOS is assumed to be in the first partition in the example above (hd1).
When finished type
.B menu
to see if the menu looks right.  If so hit '=' to start Minix.
.SS Names
A standalone machine will have to be given a name.  In
.B /etc/hostname.file
change "noname" into the name you want the machine to have.
.SS "Adding the Sources"
Type these commands to add the /usr/include, /usr/src, and /usr/man trees:
.PP
.XB "cd\0/usr"
.XB "vol\0720\0/dev/fd0 | zcat | tar\0xvfp\0\-"
.PP
And insert the system source floppies (\fBSYS.\fInn\fR) one by one in the
proper order.  (The number 720 is the size of the images on floppy.  Replace
by 1440 if you combined the images two by two.)
.PP
Use exactly the same commands to extract the (\fBCMD.\fInn\fR) set to obtain
the /usr/src/commands tree with the source files of all the utilities.  On a
disk space starved machine you could opt to do without, these sources are not
absolutely necessary to understand Minix.
.SS Active on Boot
You may want to make the Minix partition active so that it is automatically
booted.  With DOS
.B fdisk
or Minix
.BR part ,
mark the primary partition that contains Minix active.  Using the menu you
made earlier you can boot either Minix or DOS at a keypress.  You can even
set timeouts.  To boot Minix automatically after 5 seconds:
.PP
.XB "main()\0{trap\05000\0minix;\0menu}"
.PP
See
.BR monitor (8)
for all the details on the monitor.
.PP
If you don't trust this then you can rig up a diskette that boots the Minix
partition when left in the drive:
.PP
.XB "installboot\0\-m\02\0/dev/fd0\0/usr/mdec/masterboot"
.PP
The number 2 indicates the hard disk partition that must be booted, you can
use the numbers 1 to 9 for hd1 to hd9.
.SS Devices
A crash course on the Minix devices in
.BR /dev :
The two hard disks are named
.BR hd0
and
.BR hd5 .
These "multiple of five" devices address the entire hard disk, from the
first to the last byte.  Each disk has four partitions, for disk 0 they are
.BR hd1 ,
.BR hd2 ,
.BR hd3 ,
and
.BR hd4 .
And for disk 1 they are named
.BR hd6 ,
.BR hd7 ,
.BR hd8 ,
and
.BR hd9 .
These partitions may contain file systems,
.B hd1
often contains the MS-DOS "C:" file system.  Minix can use these partitions
for file systems too, but you can also partition one of these "primary
partitions" into four so-called "subpartitions".  The subpartitions of
.B hd1
are named
.BR hd1a ,
.BR hd1b ,
.BR hd1c ,
and
.BR hd1d .
The other partitions may have four subpartitions that are named in the same
way by adding a letter from
.B a
to
.BR d .
So one disk may have four partitions, and 16 subpartititions total.  SCSI
disks are named in the same way, from
.BR sd0
to
.BR sd39d
for all possible devices for all eight SCSI targets.
The two floppy disks are
.BR fd0
and
.BR fd1 .
Each may have four partitions named
.BR fd0a ,
.BR fd0b ", ..."
.BR fd1d .
The command
.B MAKEDEV
knows how to make devices, and
.B DESCRIBE
can tell you what an unknown device may be, or even what all devices in
.B /dev
may be if called without arguments.  Devices are described fully in
.BR dev (4),
and in the device specific manual pages like
.BR fd (4)
and
.BR hd (4).
.SS Editors
The editors available are
.B elvis
(a
.B vi
clone),
.B elle
(a simple
.B emacs
clone),
and the old Minix
.B mined
editor.  Of these editors only elvis can recover your file after a system
crash.  Only
.B mined
is available at installation time.  (All you need to know about mined right
now is that CTRL-X gets you out of it.)
.SS "Installing on a \s-2SCSI\s+2 disk"
Using a disk other than a
.B hd
disk complicates things a bit.  The Boot Monitor uses the BIOS, so it names
all disks with
.B hd
names.  So it is
.B boot hd1
to boot partition 1, and
.B "ramimagedev=sd2a"
to tell Minix its root partition.  If you have both a normal and a SCSI disk
then the disks may be
.B hd0
and
.B hd5
to the Monitor, and
.B hd0
and
.B sd0
to Minix.
.SS "National keyboards"
The directory
.B /usr/lib/keymaps
contains keymap tables for several national keyboards.  If you have a German
keyboard for instance, then
.PP
.XB "loadkeys\0/usr/lib/keymaps/german.map"
.PP
will load the German key translation table into the keyboard driver.  Copy
the map to
.B /etc/keymap
once Minix is installed on the hard disk, because having to type a key
sequence like one of these:
.PP
.XB "loadkezs\0\-usr\-lib\-kezmaps\-german.map"
.XB "loqdkeys\0=usr=lib=key,qps=french.,qp"
.PP
on a reboot gets a bit annoying after a while.  Send corrections and new
keymaps to the person named below.  (Do not send a Dutch keymap, buy
yourself a real keyboard instead.)
.SH SUGGESTIONS
Below are a few useful suggestions.  Some of the information can be of use
in other situations than described here.
.SS "Low on memory"
The normal installation requires that you have enough memory for a large RAM
disk.  You can still install Minix normally if you either have a high density
diskette drive for a combined root+usr floppy, or you have two floppy drives
of at least 720 kb.  Before booting you have to set the variable
.B rootdev
to the same value as
.BR ramimagedev .
This is slower then a RAM disk, but saves a lot of memory.
.PP
The automatic installation script knows how to handle this new situation.
If you install manually then you have to use
.PP
.XB "cpdir\0\-vx\0/\0/mnt"
.PP
to copy the root device to disk.  When it is time to fill /usr and you only
have one floppy drive then hit DEL to get out of the installation script and
reboot as described in "Testing".  You can then finish the installation
manually.
.SS "Low on memory and only one 720 kb floppy drive"
If you only have one 720 kb floppy drive and your system is low on memory
then you can use the \s-2TINYROOT\s+2 boot image.  This image contains a
small kernel with only the BIOS disk driver, and a small root file system.
You can use this disk to boot your machine.  Use the normal \s-2ROOT\s+2 to
install the root file system.  Keep booting your machine with
\s-2TINYROOT\s+2 until you have compiled a small kernel for your system.
Use the
.B rootdev
boot variable to select the hard disk root file system.  Do
.B not
use \s-2TINYROOT\s+2 for anything other than booting, always use
\s-2ROOT\s+2 when mentioned.
.SS "Floppy drive 1 is a high density drive"
If you would like to install from floppy drive 1 then you need to copy at
least one sector from the \s-2USR\s+2 image onto a diskette for drive 0.
The \s-2USR\s+2 bootstrap has been rigged to boot the other drive.
.SS "Installing on a second hard disk"
Minix doesn't care if it is installed on the second disk of a system with
two disks.  The only problem is to get it booted.  You can either rig up
a diskette to boot Minix as shown earlier, or you can use the same trick
on the first disk.  The command
.PP
.XB "installboot\0\-m\05\0/dev/hd0\0/usr/mdec/masterboot"
.PP
will lock the first disk into booting the second disk.  Note that this
command modifies the disk outside a Minix partition, overwriting a bit of
code that has likely been put there by DOS fdisk.  First verify that the
Boot Monitor can boot a DOS partition, because then the Minix master
bootstrap can do it too.
.SS "Lots of memory"
You will have a hard time making Minix run out of 3 Mb memory.  Memory you
can spare can be used for a "second level block cache" on the RAM disk.  The
File System uses the second level cache to store copies of disk blocks that
are pushed out of the normal (primary) block cache.  The size of the primary
cache is compiled into the FS server, but the size of the second level cache
can be set with the
.B ramsize
boot variable.  For Minix running in 286 mode you can set ramsize between 0
and 512.  512 kilobytes is enough to keep most of the compiler cached.
Minix-386 can have a second level cache of up to 1024 kilobytes.  The second
level cache is a poor solution for Minix-386 however.  The first thing to do
when you set out to compile a new kernel yourself is to make a big primary
block cache by enlarging the appropriate
.B NR_BUFS
and
.B NR_BUF_HASH
constants in <minix/config.h>.  Disable the second level cache and set
.B ramsize
to 0.  Alas the 286 can only address 64 kb at a time, so you can't enlarge
its primary block cache.
.SS "Lots of disk space"
The maximum file system size is 1 Gb for Minix-386 and 128 Mb for
Minix-86.  (Minix-86 can handle larger file systems, but
.B fsck
can't check them.)  Note that a Minix file system can only contain 65535
inodes (files), so the average file should be 16 kb to completely fill it.
It may be better to make two smaller file systems.  Besides, fsck takes ages
on a large file system.
.PP
.SH SYSTEM ADMINISTRATION
The system has been set up with the idea that working as root is a bad thing
to do.  As root you are in no way protected from doing stupid things.  So
don't do development as root, work as
.BR bin !
Only in exceptional cases do you want to become root.  Being root is fun for
wannabe hackers, administrators know better.
.PP
To make life easier for bin, some programs like
.BR su (1),
.BR install (1)
and
.BR shutdown (8)
treat bin and other members of the operator group as special and allow them
the privileges of root.  (One is an operator if one's
group id is zero.)  Operators should share the shadow password of root by
having
.B ##root
in their password field.  This way they all have one face (password)
to the outside world, forming no greater security risk than root alone.
.PP
The home directory of bin contains one important Makefile.  You can use it
to recompile all the commands and libraries of the system.  Type
.B make
to see the usage message.  If you want to compile just one command then you
can simply type
.B make
to do so.  To put it in its proper place you have to type
.BR "make install" .
Read the Makefiles in the
.B commands
and
.B lib
subdirectories to understand how everything is put together.  If you are
tight on memory then
.B make
may fail to traverse down the source tree and also compile things.  You will
have to type
.B make
in each subdirectory.  You can run make in /usr/src at the end to see if
you've missed something or not.
.PP
The login shell of bin is
.BR ash ,
the BSD shell.  It has been modified to offer simple line editing using the
.BR editline (3)
library.
.B Ash
is rather big, so you may have to change bin's shell back to
.B /bin/sh
with
.BR chsh (1)
if you are low on memory.  Do not change root's shell to ash, and do not
replace /bin/sh by ash.  It may run out of memory at the wrong moment.
.PP
The kernel is not compiled from the master Makefile.  To make a new kernel
you have to step into the
.B tools
directory.  There you can run four different make commands:
.PP
.TP
.B make
This makes all the different kernel parts and combines them in the file
named
.BR image .
.TP
.B make fdboot
As above and then makes a boot floppy that you can use to restart your
system with.  You are prompted for the floppy device name.
.TP
.B make hdboot
First makes the image file and then copies it into the directory
.BR /minix .
If there are already two images in that directory then the newest image will
be removed to make space for this newer image.  It is assumed that the
oldest image is the most stable system image, one that always works, and
that the newest image is experimental.  Check beforehand what
.B /minix
contains before you run
.BR "make hdboot" .
Remove the oldest image if you want another image to become the stable
image.  The Boot Monitor chooses the newest image in
.B /minix
to boot.  You can use the monitor command
.B ls minix
to view the images present, and set the
.B image
variable to the full name of the image you want to use instead if the newest
doesn't work.  The images in
.B /minix
are named using the Minix release and version numbers with an extra revision
number added to distinguish the images.
.PP
The first new kernel you would like to make is one configured for your
system.  The kernel you are running now contains several hard disk drivers
you don't need, and it does not have a TCP/IP server that you may want to
have.  In <minix/config.h> you can find a number of
.BI ENABLE_ XXX
variables that can be set to
.B 0
to exclude, or
.B 1
to include a particular driver.  Another driver related variable is
.BR DMA_SECTORS .
This variable sets the size of a buffer used by DMA based disk drivers (all
but the floppy, AT, and Adaptec drivers).  Raise its value to greatly
improve throughput, especially writing.  A value of 16 shows good results.
(The BIOS driver benefits most, because it is a long way to the BIOS from
protected mode, especially from 286 protected mode.)  The
.B NR_PTYS
variable sets the number of pseudo-ttys.  You need pseudo-ttys to be able to
login remotely over a network with the
.B rlogin
command.  Each remote login session needs one pseudo-tty.  If you fear that
the system will now run out of processes then increase
.BR NR_PROCS .
Configuring a new kernel is sometimes not enough to enable new devices, you
sometimes need to use the
.B MAKEDEV
command to make new device files in
.BR /dev .
For pseudo-ttys you also have to check if
.B /etc/ttytab
mentiones the new devices.
.PP
New additions to the system can be made in the
.B /usr/local
tree.  An empty directory tree has been set up for you and binaries and
manual pages are already in the search paths.  You can make a new user entry
with the
.B adduser
command.
.PP
The
.B TZ
variable in
.B /etc/profile
tells the time zone offset from the wall clock time to GMT.  You have to
change it for your time zone.  (See
.BR TZ (5).)
.PP
The function keys produce debug dumps, showing various interesting data
about the system.  F1 lists processes and F5 shows ethernet stats, which
may be of use now.  Read
.BR console (4)
to know all the details of the screen and keyboard.
.SS "System shutdown"
You can't just turn a Minix system off.  Minix must be told to flush the
modified data in the file system cache first.  The following
commands/keystrokes can be used to exit Minix properly:
.TP
.B shutdown
First alert all users and then all processes of the impending shutdown
then halt or reboot the system in one of various ways.  See
.BR shutdown (8).
.TP
.B reboot / halt
Alert all processes of the system shutdown then reboot or halt.
.TP
.B \s-2CTRL\-ALT\-DEL\s+2
Halt the system by running
.BR "shutdown \-h now" .
.PP
Minix halts by returning to the Boot Monitor, Minix reboots by instructing
the monitor to reboot Minix.  (Minix is just a subprocess to the monitor.)
Either halt Minix and use monitor commands to escape Minix, or use
.B shutdown \-R
to reset the system.
.SH FILES
.TP 12
.B /usr/ast
Honorary home directory of Andew S. Tanenbaum.  Doubles as the place where
the default setup for a new user is found.
.SH "SEE ALSO"
.BR monitor (8),
.BR boot (8),
.BR part (8),
.BR mkfs (1),
.BR mount (8),
.BR M (8),
.BR fstab (5),
.BR hier (7),
.BR console (4),
.BR dev (4),
.BR adduser (8),
.BR TZ (5),
.BR mkdist (8),
.BR shutdown (8).
.br
"Operating Systems \- Design and Implementation" by Andrew S. Tanenbaum.
.SH NOTES
The notation
.BI < file .h>
refers to a C language include file in /usr/include.
.PP
Some of the commands have changed since earlier Minix versions.  For instance
.B mkfs
doesn't need a size argument anymore, and
.B vol
automagically determines if it needs to read or write.  Keep this in mind
if you use an older Minix version to examine the newer system.
.SH BUGS
There are many PS/2 models, all different.  Some will run Minix, some won't,
some crippled if you lie to Minix by setting
.B processor
to
.BR 86 .
Almost no PS/2 has a standard disk, so setting
.B hd
to
.B esdi
or
.B bios
will be necessary.
.PP
Except for the floppy driver none of the DMA based drivers know about DMA
being limited to a 24 bits address, i.e. the first 16 Mb.  So under Minix-386
you run a slight risk that a
.B tar
or
.B dd
command may use a buffer above 16 Mb for reading or writing to a character
device.  This only happens if the low 16 Mb is taken by some huge processes,
and you have more than 16 Mb, of course.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)