BefOS - an Operating System for the Linearly Challenged ======================================================= BefOS v2006.0204 (c)1999-2006 Cat's Eye Technologies. All rights reserved. ,---------------------------------------------------. | * 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 * | `---------------------------------------------------' 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