509 lines
13 KiB
Groff
509 lines
13 KiB
Groff
.TH MONITOR 8
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.SH NAME
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monitor, edparams \- load and start Minix, modify boot parameters
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.SH SYNOPSIS
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.B edparams
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.I device
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.RB [ command " ...]"
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.br
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.B boot.com
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.I virdisk
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.SH DESCRIPTION
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.de SP
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.if t .sp 0.4
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.if n .sp
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..
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This text describes the Boot Monitor, a boot time interactive program designed
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not only to load and start Minix, its most important task, but to also
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provide an easy to use interface to configure Minix and to boot other
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operating systems.
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.PP
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The monitor is controlled with an environment that is modeled after the
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Bourne shell. This environment is filled at startup with default values
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that depend on the machine the monitor is running on and the environment
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settings saved into the boot parameters sector (the second sector on a
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device). When the environment is loaded, the monitor executes the function
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named
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.BR main ,
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which by default starts a simple menu.
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.PP
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The environment can be manipulated at boot time from the monitor prompt,
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but may also be edited using
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.B edparams
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on a given device.
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.B Edparams
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simulates the monitor as much as it can, echoing commands it can't execute
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between brackets. It can also be used in Makefiles and scripts by giving
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it commands as arguments.
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.PP
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The MS-DOS version of the monitor, usually named
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.B boot.com
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under DOS, boots Minix from a "DOS virtual disk". (See below.)
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.SH COMMANDS
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The monitor is best described by the commands you can type to the '>'
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prompt. This is known as the "monitor mode". You can enter this mode by
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hitting the Escape key. These are the monitor commands:
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.PP
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\fIname\fP = [\fBdevice\fP] \fIvalue\fP
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.SP
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.RS
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Set environment variable.
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.br
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Changes the value of
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.I name
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to
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.IR value .
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The optional word
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.B device
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marks
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.I name
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as being subject to device translation. (See the section on devices.) These
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(name, value) pairs are passed to the kernel who uses them to configure
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itself. These variables are passed by default:
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.SP
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.B rootdev
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.RS
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This is the device used as your root device. It is by default set to
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.BR ram,
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which means that the device specified by
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.B ramimagedev
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will be loaded into the RAM disk and used as root. If you change this
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variable then a physical device will be used as root, and the RAM disk will
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be uninitialized and have the size specified by
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.BR ramsize .
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.RE
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.SP
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.B ramimagedev
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.RS
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Describes the device to use to initialize the RAM disk if
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.B rootdev
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is set to
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.BR ram .
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It's by default set to
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.BR bootdev ,
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a special name for the device the monitor booted from.
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.RE
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.SP
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.B ramsize
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.RS
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The size of the RAM disk. If the RAM disk is used for the root file system
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then the root file system is stretched out to
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.B ramsize
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if possible.
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.RE
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.SP
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.B processor
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.RS
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Set by default to
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.BR 86 ,
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.BR 186 ,
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.BR 286 ,
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.BR 386 ,
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.BR 486 ", ..."
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depending on the hardware you have. You can set it to a smaller value to
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test your kernel in a more limited environment.
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.RE
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.SP
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.B bus
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.RS
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The type of system bus, either
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.BR xt ,
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.BR at
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or
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.BR mca .
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This answers basic questions like: "How many interrupt controllers and how
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to initialize?" Or: "Does the keyboard have LEDs?"
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.RE
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.SP
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.B memsize
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.RS
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Kilobytes of conventional memory. This is the amount of RAM within the
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first megabyte.
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.RE
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.SP
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.B emssize
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.RS
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Kilobytes of extended memory.
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.RE
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.SP
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.B video
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.RS
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Describes capabilities of the VDU:
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.BR mda ,
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.BR cga ,
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.B ega
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or
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.BR vga .
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.RE
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.SP
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.B chrome
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.RS
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Either
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.B color
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or
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.BR mono .
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.RE
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.SP
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.B console
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.RS
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If set to a hexadecimal value makes the monitor set the BIOS video mode to
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this value. This allows the use of video modes with more rows or colums
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than the standard 80x25 mode. The kernel must of course be able to handle
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a nonstandard mode. More parameters may follow the mode number.
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.B Warning:
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Not all monitors can handle all of the modes, some may generate frequencies
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that can damage your monitor. Read the manual of card and monitor for
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details.
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.RE
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.SP
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Two variables are only used by the monitor, even though they are passed to the
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kernel too:
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.SP
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.B image
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.RS
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The name of the file containing the kernel image, by default
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.BR minix .
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If it refers to a directory however then the newest file inside the
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directory is chosen to be the kernel image. The names inside
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.B /minix/
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are best set to the Minix version you are using, which looks good when the
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monitor prints its name. Rules for pretty printing image names:
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.RS
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.SP
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A '/' or '_' is changed to a space.
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.SP
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The first letter is changed from lowercase to uppercase.
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.SP
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An 'r' if followed by a digit changes to " revision ".
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.RE
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.RE
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.SP
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.B label
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.RS
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If set then only processes marked with this label or without a label are
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loaded from the image.
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.RE
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.SP
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.B Installboot \-boot
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will create functions to select images and labels. These functions will set
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label and image and echo what you selected. The two numbers separated by a
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colon used as an image name tell the starting sector and sector count of the
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image on disk.
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.RE
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.SP
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\fIname\fP() { ... }
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.RS
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Define function.
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.br
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Functions may be used to bundle a set of commands, so that you can easily
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boot Minix with a different set of parameters then normal. E.g.
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.SP
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.RS
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ram() { rootdev=ram; boot }
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.RE
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.SP
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will allow you to run Minix with the root device on RAM for a change, if
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you normally use a real device as root. The only pre-set function is
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.B main
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with default value
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.BR menu ,
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which is the default command executed by the monitor. You can use newlines
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after the ')' token, the monitor will then use a '+' prompt and ask for the
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rest.
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.RE
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.SP
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\fIname\fP(\fIkey\fP) { ... }
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.RS
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Define kernel selecting function.
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.br
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The menu command uses functions like these to add menu entries to select
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a different kernel from a boot disk.
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.B Installboot \-boot
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produces these functions when the images are labeled. The label
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.B AT
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would give:
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.SP
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.RS
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AT(a) {label=AT;image=42:626;echo AT kernel selected;menu}
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.RE
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.SP
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With the menu option:
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.SP
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.RS
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a Select AT kernel
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.RE
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.SP
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Typing
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.B a
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will then execute the
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.B AT
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function above.
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.RE
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.SP
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\fIname\fP(\fIkey\fP,\fItext\fP) { ... }
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.RS
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User defined menu option.
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.br
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This variant may be used to make any menu entry you like:
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.SP
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.RS
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dos(d,Boot MS-DOS) { boot hd1 }
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.RE
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.SP
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.I Text
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may be anything, even parentheses if they match.
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.RE
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.SP
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.I name
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.RS
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Call function.
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.br
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If
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.I name
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is a user defined function then its value is expanded and executed in place of
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.IR name .
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Try a recursive one like 'rec() {rec;xx}' one day. You can see the monitor
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run out of space with nice messages about using
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.BR chmem (1)
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to increase it's heap.
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.RE
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.SP
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\fBboot\fP [\fB\-\fP\fIopts\fP]
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.br
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\fBboot\fP \fIdevice\fP
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.RS
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Boot Minix or another O.S.
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.br
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Without an argument,
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.B boot
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will load and execute the Minix image named by the
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.B image
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variable. With options the variable
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.B bootopts
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is first set to
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.BI \- opts
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before Minix is started, and unset when Minix returns. With a
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.I device
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argument,
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.B boot
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loads the boot sector of
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.I device
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into memory and jumps to it, starting another operating system. You would
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normally use partitions on the first hard disk for this command (hd[1\-4]),
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using hd0 will also work (choosing the active partition). One can also boot
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devices on the second hard disk (hd[5\-9]) if the bootstrap writer did not
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hardwire the disk number to disk 0.
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.br
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Some Operating Systems can only be booted from the active partition, if
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you use a '*', e.g.
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.BR "boot *hd3" ,
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then partition 3 is first made active. You'll then need to use
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.B installboot \-master
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with a fix key to forcefully boot the Minix partition at startup.
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.RE
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.SP
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\fBdelay\fP [\fImsec\fP]
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.RS
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Delay (500 msec default).
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.br
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Fast booting speed was one of the objectives when this program was created,
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so a hard disk boot usually takes only a fraction of a second. If you need
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some time (to hit Escape, or stare at the numbers) you can use
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.B delay
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to make the monitor pause for a specified amount of time. To specify a delay
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just before Minix is started, you can set the variable
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.B delay
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to a number of milliseconds. Example:
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.SP
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.RS
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main() {delay 250; delay=500; boot}
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.RE
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.SP
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Look at this carefully, 'delay 250' means: "wait 1/4 sec now!",
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while 'delay=500' means: "wait 1/2 sec after loading Minix".
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.SP
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If you use
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.B delay=swap
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then the monitor will wait until you have inserted a root diskette and typed
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RETURN.
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.RE
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.SP
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\fBecho\fP \fIword\fP ...
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.RS
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Print these words.
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.br
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Used to tell you that you just selected image X.
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.RE
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.SP
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\fBls\fP [\fIdirectory\fP]
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.RS
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List contents of a directory.
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.br
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Useful when looking for kernel images.
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.RE
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.SP
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.B menu
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.RS
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Menu driven startup.
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.br
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This command allows you to execute functions defined with a
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.IR key .
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If no menu functions have been defined then
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.B menu
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will use this one hidden built-in function:
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.SP
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.RS
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*(=,Start Minix) { boot }
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.SP
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.RE
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Kernel selecting functions only add new options to this set, but if you
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define a two argument function yourself then the above one is no longer
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shown, allowing you to customize the menu completely. Your first
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function definition should therefore be one that starts Minix.
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.SP
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Menu entries are shown in the same order as
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.B set
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shows them. If you don't like the order then you have to unset the
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functions and retype them in the proper order.
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.SP
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If you type a key then a scheduled trap is killed and the appropriate menu
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function is executed. If you need more time to choose then hit the
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spacebar. A key not on the menu also kills a trap, but does nothing more.
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.RE
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.SP
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.B save
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.RS
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Save environment.
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.br
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This will save all the environment variables and functions with nondefault
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values to the parameter sector (the second sector on the boot device), so
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they are automatically set the next time you boot the monitor.
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.RE
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.SP
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.B set
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.RS
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Show environment.
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.br
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Show the current values of the environment variables and functions. Default
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values are shown between parentheses to distinguish them from values that
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were explicitly set.
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.RE
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.SP
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\fBtrap\fP \fImsec\fP \fIcommand\fP
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.RS
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Schedule command.
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.br
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Schedules a command to be executed after
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.I msec
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milliseconds. Only the monitor mode cannot be interrupted, a scheduled trap
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is killed when the prompt is printed. Example:
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.SP
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.RS
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main() {trap 10000 boot; menu}
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.RE
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.SP
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This gives you 10 seconds to choose a menu option before Minix is booted.
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.RE
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.SP
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\fBunset\fP \fIname\fP ...
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.RS
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Unset environment variables.
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.br
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Removes the named variables and functions from the environment, and sets
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special variables back to their default values. This is also the only way
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to remove the "device name translation" property from a variable.
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.RE
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.SP
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\fBexit\fP
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.RS
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Exit the monitor
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.br
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Reboot the machine, exit to Minix or exit to DOS as appropriate.
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.RE
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.SH DEVICES
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The Minix kernel can't do anything with device names, so they have to be
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translated to device numbers before they are passed to the kernel. This
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number is found under the st_rdev field (see
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.BR stat (2))
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of the file on the boot file system. The monitor will look for the device
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file with the working directory set to '/dev'. If it can't find the device
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name then it will translate names like 'ram', 'fd1', 'hd6', 'hd3a', and 'sd2'
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to what it itself thinks the numbers should be.
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.PP
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The special name
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.B bootdev
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is translated to the name of the device booted from, like 'fd0', or 'hd3', and
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then searched for in /dev.
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.B Bootdev
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can't be translated to a device other then the fd or hd devices, so SCSI
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devices for instance must be named explicitly.
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.SH EXTENSIONS
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A few extensions have been made to this program for kernel hackers. They
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may be triggered by setting bits in the flags word in the kernel startup
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code (the mpx file.) The flag bits are:
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.TP 10
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0x0001
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Call kernel in 386 mode.
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.TP
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0x0002
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Do not make space for the bss areas of processes other then the kernel.
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.TP
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0x0004
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Use the stack size set by
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.BR chmem (1).
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.TP
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0x0008
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Load MM, FS, etc. into extended memory.
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.TP
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0x0010
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No need to patch process sizes into the kernel.
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.TP
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0x0020
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The kernel can return to the monitor on halt or reboot.
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.SH "MS-DOS MONITOR"
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Minix-vmd has a version of the monitor that runs under MS-DOS to boot
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a "DOS virtual disk". It is a simple COM program that interprets an MS-DOS
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file as a disk, loads a Minix kernel from the active partition in the same
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way as the BIOS based monitor, and executes it to start Minix. All the
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monitor commands function in the same way, except for the
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.B boot
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command, it can only load Minix. The memory that MS-DOS has in use is copied
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out of the way when Minix takes control, and is put back in place when Minix
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exits. This memory shuffling also happens when the BIOS disk driver makes
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BIOS calls, slowing things to a crawl. It is better to use a Minix driver.
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The MS-DOS monitor does not work if there is a memory manager active that
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runs in 386 protected mode, like EMM386.
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.SH "SEE ALSO"
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.BR chmem (1),
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.BR stat (2),
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.BR installboot (8),
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.BR usage (8),
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.BR boot (8).
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.SH BUGS
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The
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.B delay
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command will hang forever on the original IBM PC (not the XT!). Not that it
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matters, as everything takes forever on that box.
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.PP
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Reading the first sector to boot a floppy (e.g.
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.BR "boot fd1" ),
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is done using whatever floppy parameters boot currently has available. This
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will probably always work.
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.PP
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The two forms of
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.B delay
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are a crock.
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.PP
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The word
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.B emssize
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comes from EMS, that has to do with expanded memory, not extended memory.
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.SH ACKNOWLEDGMENTS
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Guy Helmer, for the floppy sensing code that somehow disappeared into the
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boot block.
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.PP
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Earl Chew, for the inspiration his ShoeLace package provided, unless he wants
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to file a "look and feel" suit against me, then I will say I modeled it after
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the SunOS ROM boot monitor, which is also true.
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.SH AUTHOR
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Kees J. Bot (kjb@cs.vu.nl)
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