BefOS - an Operating System for the Linearly Challenged
=======================================================
BefOS v2006.0204
(c)1999-2006 Cat's Eye Technologies. All rights reserved.
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| * WARNING! * CAUTION * PROCEED AT YOUR OWN RISK * |
| |
| * THIS PRODUCT IS PROVIDED "AS IS" * |
| |
| * CAT'S EYE TECHNOLOGIES CAN NOT BE HELD LIABLE * |
| * FOR ANY DAMAGES RESULTING FROM ITS USE * |
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What is it?
-----------
BefOS is a toy OS written in 100% 8086 assembler. It requires the
following hardware (or a decently emulated version thereof):
Processor: 100% Intel 8086+ Compatible
BIOS: 100% IBM PC Compatible
Video: 100% VGA Compatible
Keyboard: 100% Standard 101/102-Key Compatible
RAM: 640K base, 8M extended
Storage: 1.44M floppy drive 0 (A:)
BefOS was originally written in Borland's Turbo Assembler format,
but this version has been translated to use the free assembler
NASM.
Booting into BefOS
------------------
Using Bochs or some other emulator: point the emulated A: drive of
the emulator at the file disk/befos.flp, and boot from the floppy.
The 'test' target in the top-level (and disk/) Makefile will run
Bochs automatically on this floppy image.
Using Windows: run BEKERNEL.COM. (Note that I'm not sure if this
works anymore in the NASM version; I haven't tried it. You still
need a blank floppy in drive A:, though.)
For real: install the floppy image (disk/befos.flp) onto a blank,
1.44M floppy disk, using a tool such as 'fdimage.exe' (which is
available at ftp://ftp.freebsd.org/pub/FreeBSD/tools/). Then
reset your computer and boot off that floppy.
Using BefOS
-----------
Once you've booted into BefOS, you'll see a blue screen with some stuff
on it.
Here is a quick-and-dirty guide to the top line of this display:
B the BefOS 'logo.'
(light) yellow = working, green = worked, red = failed
(4 hex digits) amount of base memory available, in K
(4 hex digits) amount of extended memory available, in K
(green bar)
(4 hex digits) link to next cluster of current cluster
(4 hex digits) link to previous cluster of current cluster
(4 hex digits) link to application cluster of current cluster
(4 hex digits) link to colour cluster of current cluster
(4 hex digits) link to help cluster of current cluster
(green bar)
(16 OEM chars) description of current cluster
(green bar)
(4 hex digits) value of last keystroke detected
(2 hex digits) value of current byte under cursor
(4 hex digits) current cluster number, starts at 0
And here are some key bindings: (NYI=Not Yet Implemented):
PgUp Up One Cluster
PgDn Down One cluster
Ctrl-PgUp Link to Previous Cluster (header)
Ctrl-PgDn Link to Next Cluster (header)
F1 Link to Help Cluster (header)
Up Move Pointer Up One Row
Down Move Pointer Down One Row
Left Move Pointer Left One Column
Right Move Pointer Right One Column
^2 (^@) Write 0
^A to ^Z Write 1 - 26
ESC Write 27
^\ Write 28
^] Write 29
^6 (^^) Write 30
^- (^_) Write 31
Space Write 32
!..~ Write 33 - 126
Ctrl-Bkspc Write 127
Alt-L Load (refresh from disk)
Alt-R Run (if AA==ffff, executes machine code)
F4 Change Properties (Header)
Alt-- Delete Properties (Header)
Alt-= Initialize Properties (Header)
Alt-M show More data on screen
Alt-N show less data on screeN
Alt-G Go to cluster number
NYI*1 Alt-E Edit: allow writes
Alt-U fill cluster Uniformly with current byte
Alt-C Copy cluster data & header to clipboard
Alt-P Paste cluster data & header from clipboard
Alt-H toggle High bit
Alt-S Save (commit changes to data & header to disk)
Alt-Q Quit (MS-DOS only)
*2 Alt-I Install cluster from file (MS-DOS only)
*1: writes are always allowed in this version so BE CAREFUL WITH ALT-S.
*2: type the filename into the start of the cluster buffer and
terminate it with a null (Ctrl-2)
Cluster Format
--------------
Each cluster has a 'header' which is in fact stored in the LAST
48 bytes of the second cluster. The first 2000 bytes are data.
The header is structured thus:
+------------------------------------------------+
|VVNNPPAACCHHxxxxxxxxxxxxxxxxxxxxDDDDDDDDDDDDDDDD|
+------------------------------------------------+
VV = word indicating header type.
bef0 indicates standard BefOS header, the only type supported.
NN = word containing the cluster number of the next cluster.
0000 indicates that there is no next cluster.
PP = word containing the cluster number of the previous cluster.
0000 indicates that there is no previous cluster.
AA = word containing the cluster number of the first cluster of
the application for which this is a document.
0000 indicates that there is no special application for this
generic document.
ffff indicates that this IS an application written in
x86 machine code.
CC = word containing the cluster number of
this cluster's colour cluster.
0000 indicates that this cluster is monochrome.
HH = 2 bytes containing the cluster number of
this cluster's help-cluster.
0000 indicates that this cluster is helpless.
xxxxxxxxxxxxxxxxxxxx = 20 bytes reserved.
DDDDDDDDDDDDDDDD = 16 bytes ASCII description e.g. "Seismology Now"
------------------------------------------------------------------
But the following is more like what I would like it to be...
------------------------------------------------------------------
First, we say that 1 "screen" is 4096 bytes:
80x25char + 80x25colour + 96 bytes header.
A "tableau" is a set of 80x25 screens = 2000 * 4K = 8M.
There is one tableau on the computer which maps to it's extended RAM.
One 1.44M floppy disk can contain six columns = 150 screens.
Header:
+------------------------------------------------+
|VVAAxxxxxxxxxxxxDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD|
|DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD|
+------------------------------------------------+
VV = word indicating header type.
bef0 indicates standard BefOS header, the only type supported.
AA = word containing the cluster number of the first cluster of
the application for which this is a document.
0000 indicates that there is no special application for this
generic document.
ffff indicates that this IS an application written in
x86 machine code.
xxxxxxxxxxxx = 12 bytes reserved.
DD..DD = 80 bytes ASCII description.
Building BefOS
--------------
BefOS can be built on FreeBSD (and probably Linux and Cygwin.)
Just type 'make clean all' from the top level to build it all.
Here is what is in the various directories:
bin/
amalgam8 Constructs a boot disk image from BefOS objects
extract8 Extracts BefOS objects from a boot disk image
txt2page Turns a text file into a BefOS object file
mkbfinc.pl Used during build to generate list of API calls
disk/ Contains bootable BefOS boot disk images
obj/ Contains BefOS objects that will be amalgamated
src/ Contains source code for BefOS:
apps/ Source code for the BefOS applications installed
boot/ Source code for the boot disk's boot block
inc/ Include files shared by many BefOS object sources
kernel/ Source file for the core components of BefOS
page/ Misc files that become BefOS pages on the disk
tools/ Source code for the util programs put in bin/
turbo/ The original Turbo Assembler sources for BefOS