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Format fix 2004/gavin/README.md

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Also renamed gavin_install.txt to gavin.md and updated formatting.

chmod +x prim (even though it won't work in some modern platforms - at
least if it wasn't corrupted at some point it might in some; it's a
32-bit ELF LSB).
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Cody Boone Ferguson committed 2023-04-24 10:41:29 -07:00
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2004/gavin/README.md
+49 -50
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@@ -1,10 +1,7 @@
# Best of Show
Gavin Barraclough
Flat 20, 83 Newton Street,
Manchester,
M1 1EP,
U.K.
Gavin Barraclough
UK
## To build:
@@ -27,8 +24,8 @@ To enjoy the results (on a Linux/x86 machine):
su
```
Make a floppy with an ext2 filesystem (mke2fs /dev/fd0), mount it under /mnt/floppy.
Then:
Make a floppy with an ext2 filesystem (`mke2fs /dev/fd0` replacing `fd0` with
whatever the floppy device is!), mount it under `/mnt/floppy`. Then:
```sh
@@ -37,7 +34,7 @@ cp kernel fs.tar lilo.conf boot.b /mnt/floppy
NOTE: If the version of your lilo is not 21.4, use the appropriate boot.b file.
NOTE: If your floppy drive is not /dev/fd0, edit lilo.conf appropriately.
NOTE: If your floppy drive is not `/dev/fd0`, edit lilo.conf appropriately.
```sh
lilo -C /mnt/floppy/lilo.conf
@@ -67,33 +64,37 @@ Press and hold any key.
## Judges' remarks:
Over the years, we've seen a program that dumps core
if executed on a "wrong" architecture immediately (1984/mullender),
or after a while (2001/bellard). This entry will happily compile and
execute on any architecture - the trick is that the result, to be useful,
must be produced (and can only be enjoyed) on a particular architecture.
We have not decided yet whether to disallow this for future contests.
Over the years, we've seen a program that dumps core if executed on a "wrong"
architecture immediately ([1984/mullender](/1984/mullender/mullender.c)), or
after a while ([2001/bellard](/2001/bellard/bellard.c)). This entry will happily
compile and execute on most any architecture - the trick is that the result, to
be useful, must be produced (and can only be enjoyed) on a particular
architecture. We have not decided yet whether to disallow this for future
contests.
If you do not want to mess with a floppy and you use GRUB, see below
in the author's notes.
You can put additional text files in fs.tar for browsing with vi.
If you do not want to bother rebooting your computer at all,
see http://bellard.org/ for QEMU (Fabrice Bellard is an IOCCC 2001 winner),
but your experience will be limited (replace -DK=0 with -DK=1 in the Makefile,
and you will have to move the mouse to trigger the initial screen update).
You can put additional text files in `fs.tar` for browsing with vi. If you do
not want to bother rebooting your computer at all, see <http://bellard.org> for
QEMU ([Fabrice Bellard](/winners.html#Fabrice_Bellard) is an IOCCC 2001 winner),
but your experience will be limited (replace `-DK=0` with `-DK=1` in the
[Makefile](Makefile), and you will have to move the mouse to trigger the initial
screen update).
The judges were able to write a few more programs to run on this OS
What are the limitations for such programs?
What you can do and what you cannot do in such programs?
The program called "prim", written by the judges,
computes and prints prime numbers.
The program called `prim`, written by the judges, computes and prints prime
numbers.
## Author's remarks:
This is a 32-bit multitasking operating system for x86 computers,
with GUI and filesystem, support for loading and executing user
applications in elf binary format, with ps2 mouse and keyboard drivers,
applications in elf binary format, with PS/2 mouse and keyboard drivers,
and vesa graphics. And a command shell. And an application -
a simple text-file viewer.
@@ -107,16 +108,16 @@ which is partially defined by the OS, and partially for
the application's own use.
The program compiles into a tool to build a kernel image,
so having built the program, the makefile will run it,
piping the output into a file called 'kernel'.
The makefile will then proceed to build a root filesystem image.
so having built the program, the [Makefile](Makefile) will run it,
piping the output into a file called `kernel`.
The Makefile will then proceed to build a root filesystem image.
This involves rebuilding the program with different compiler flags,
then building a tar file containing the resulting programs
(the filesystem format supported by the OS is the tar-file format).
For further usage information see 'gavin_install.txt'.
For further usage information see [gavin.md](gavin.md).
The filenames 'vi' and 'sh' are significant, and should not be changed.
The filenames `vi` and `sh` are significant, and should not be changed.
### Known 'features'
@@ -127,40 +128,38 @@ it will reappear on the right, and vice-versa.
If it goes off the top or bottom, it will go and corrupt some memory.
The file system is kinda optimistic about matching names, so,
for example if you type the command 'shell' into a command-line
it will execute the program 'sh' - close enough a match for it.
for example if you type the command `shell` into a command-line
it will execute the program `sh` - close enough a match for it.
The elf binaries are not loaded at the correct address,
and their entry point must be the start address of the text segment.
The ELF binaries are not loaded at the correct address, and their entry point
must be the start address of the text segment.
The keyboard driver can cope with the basic alpha-numeric keys,
but gets confused by fancy things like 'shift' or 'backspace'.
but gets confused by fancy things like `shift` or `backspace`.
In the text-file viewer, 'vi', the up/down and pgup/pgdn keys
In the text-file viewer, `vi`, the up/down and PgUp/PgDn keys
scroll up or down by one line. There is nothing to stop you
[from] scrolling above the top of the file, and pressing any
other keys may have an undefined effect.
from scrolling above the top of the file, and pressing any
other keys might have an undefined effect.
The x86 is bootstrapped into 32bit mode in 6 instructions,
with 4 more to set up data/stack segments and a stack-pointer
to allow C code to be run. On top of this there are also about
a dozen instructions to switch the video card into graphics mode.
All in all, a relatively tiny number of instructions next to
the size of the C program. Also, the string is mostly composed
of data - a Linux-esque kernel header for the bootloader,
protected mode descriptor tables, keyboard maps, etc.
(I should also mention that it contains mini functions
to perform an x86 'in' and 'out' instruction - to allow
the keyboard & mouse to be driven from C code).
The x86 is bootstrapped into 32bit mode in 6 instructions, with 4 more to set up
data/stack segments and a stack-pointer to allow C code to be run. On top of
this there are also about a dozen instructions to switch the video card into
graphics mode. All in all, a relatively tiny number of instructions next to the
size of the C program. Also, the string is mostly composed of data - a
Linux-esque kernel header for the bootloader, protected mode descriptor tables,
keyboard maps, etc. (I should also mention that it contains mini functions to
perform an x86 `in` and `out` instruction - to allow the keyboard & mouse to be
driven from C code).
Porting to another architecture should be relatively easy* -
Porting to another architecture should be relatively easy\* -
the string simply needs be replaced with one containing
data & code suitable for the new target platform.
Accesses to data in the string are made relative to the define 'V',
so these may need updating as appropriate (0x90200 is the address
Accesses to data in the string are made relative to the define `V`,
so these may need updating as appropriate (`0x90200` is the address
at which a Linux bootloader loads an x86 kernel image).
* ;-)
\* ;-)
## Copyright and CC BY-SA 4.0 License: