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EDIT: i forgot to mention how to switch between terminals, although it's explained in the help "feature" of the shell. it's ctrl-alt-F# just like in linux. this of course makes it a problem to use if using an emulator under linux. in QEMU, you can use the "sendkey" command in the QEMU monitor.
if anybody wants to try what i've got done of my real-mode multi-tasking OS, here's a 1.44 MB floppy image:
it has a shell, and supports FAT12 and FAT16 filesystems. there are a few binaries that can be executed. it automatically runs shells on terminals 1 to 4. the shell is very basic, run help for info. it can't even list a directory yet.
you can run "exec plasma.bin" to see the animated plasma demo...
i have some kind of bug when i fork processes though, it seems to kinda break the parent shell after you execute a couple new forks. MT86 will work on real hardware but it reads files slow because i'm not caching the FAT yet.
Last edited by miker00lz on Wed Sep 14, 2011 12:32 am, edited 1 time in total.
When I try to kill process 3 it works, but when I kill 1 or 2, it just freezes. If I kill process 0, the textmode cursor returns to 0,0 and then it freezes. If I pass kill a non-numeric argument it freezes. If I try to execute a program that doesn't exist, it displays "File fd0:/file not found" or something, and then freezes. I'm using Qemu 0.14.1 (oh, I should update...)
It looks nice, some bugs to clear up, but its a good start. The plasma program looks cool.
strange bug, i am able to reproduce it too. thanks. yes, it's just getting started as an OS. i probably released this floppy image way too early. but i was eager to get a little feedback.
i have a feeling my memory management might be a bit messed up.
interestingly, in the emulator i wrote myself (fake86, where i do almost all of my testing) and on real hardware (have tried an 8088, a 286, a 386, a 486, and a pentium -- am i strange for owning all of those??) i have no problems killing any process at all. it all functions properly. working on real hardware, i suspect it's a QEMU peculiarily.
killing process 0, i expect to cause goofiness since its the kernel. i need to just not allow killing PID 0 from the shell. and passing a non-numeric argument causes the same behavior since i'm simply using atoi() and it'll parse as "0"
the does not recognize a string as a parameter. (yet)
MT86 will get way more interesting once i drop in my TCP/IP stack, and have some kind of networking software. i think i will start with an IRC client. my friend wrote a nice one for DOS in C that should be pretty easy to port to MT86.
i guess what i can take away from the QEMU error is that on killing one of the processes, it is temporarily executing some code up in VGA RAM. it's probably all opcode 0's (one of the ADD instructions) up there, but that's definitely not good. i need to look at my process clean-up code i suppose. if there happens to be something other than 0's where it executes, something bad could happen.
you've gotta be extra careful with what's executed in real mode of course, since any process could totally lock the system and the kernel can't do a thing about it.
i could make a process that just runs CLI, HLT for example.
Chandra wrote:Hey, is your OS supposed to run under your own emulator? That's cool. Is the emulator(Fake86) self hosted?
yeah, it runs great under my emulator.
no it's not self-hosted though. the emulator is real-mode only for the guest environment, and needs a 32-bit host. i haven't taken the protected-mode plunge yet. it runs Wolf3D great though, so i am happy for the moment! http://www.youtube.com/watch?v=GIgcIgz-EQ4
ignore the sound, youtube made it sound extremely "wobbly".
i have actually made a very stripped down 16-bit version of the emulator, and that runs on my IBM XT and it runs inside fake86 (and compiles inside of using Turbo C++ 3.0!) but of course that's very different from the real version.
Pretty cool. I would like to see the source code. Is it available anywhere?
Using 700MHz Pentium III machine with 64MB of RAM because I feel like it.
ed implementation in C: main(a){for(;;;){read(0,&a,1);if(a=='\n')write(1,"?\n",2);}}
