OSDev.org

hi

i've written a simple boot program (calling it a boot loader, let alone an operating system would be way too much). it does the following:

-get a memory map from the bios
-switch to protected mode
-hook the clock and keyboard interrupt
-set up routines to display strings and numbers (hexadecimal, binary, signed and unsigned decimal) on the screen
-set up a command line
-set up a table where each entry contains a string s, a number n and a function f

when the user enters

"command param1 param1"

the table is searched for an entry where s matches command and n equals 3..if a match can be found, the addresses of param1 and param2 are pushed and the corresponding function f is called

for now i have two commands:

-"clearscreen"
-"say something"

where say is like a very primitive echo, it accepts only ONE word (no spaces)


so now that you have an idea what i can do, i would like to know where i should go next...i would like to finally tinker with multitasking but i'm not sure if there something else i should try to get done before that...how would you guys go about from here on?

thanks

martin

Devices, HD access, Floppy, drivers, Filesystems, etc
Scheduler, Malloc() function, VFS, Vmemory, ELF/EXE loading relocating and executing. If you're going to userland, systemcalls.

-JL

get a memory manager implemented, and i would suggest paging, as this will give you memory protection and allow you to allocate/free memory effectively.

from there multitasking is (theoretically) fairly simple.

i would also look into implementing a virtual filesystem (VFS) as this can be used to load drivers and mount further filesystems, once youv implemented them.

During the early stages of booting you have got no choice but to allocate memory on an ad hoc basis. However it would probably be a good idea to introduce some order into the chaos sooner rather than later. So even if not the very next thing, writing a memory manager should be one of the next things you do.