Interrupts, IDT, Etc.

[AvengerX]

I have my IDT set up, it works, keyboard and timer work, but how do i CALL interrupts? like i define an interrupt, how do i make it "go"?. oh, and where is the character generator RAM located (stores the console font data)?

[Whatever5k]

Make a software interrupt - in C:

Code: Select all

__asm__("int $0x1");

This will call the first Interrupt Service Routine...

[Pype.Clicker]

iirc, the characters table is located somewhere in the video memory, but you have to ask the VGA sequencer to use your own table (rather than pre-defined one) ... i have more info on this @ home...

http://web.inter.nl.net/hcc/S.Weijgers/ ... .htm#fonts

should help you a bit

[AvengerX]

It helps me a bit, but not as much as needed (nor does the source for some linux console font editing programs, they just call

ioctl(fd, PIO_FONT, buf);

so, that's useless.. heh. thanks

[K.J.]

where is the character generator RAM located (stores the console font data)?

IIRC, the only way to know is to call a VGA interrupt. I'm not sure which off the top of my head, a quick search through Ralf Brown's list should turn it up though.

K.J.

[AvengerX]

I know it has to do with int 10 to change the font, but i am in protected mode...

[Slasher]

you can either
Change fonts before you switch to Pmode or
from pmode,go to real mode(or vm86) change fonts then return to pmode!

[Therx]

It's possible to change the font from PMode. I think the font location in video memory is mapped near the top of the memory. I've seen a value somewhere and will try to find it

Ok found it I think its in ROM its a fairly random address found in some source code

0xF000FA6EL

Haven't checked it but it should give you access to the default char set

[Pype.Clicker]

i also do thing it's somewhere in the video memory, and i think you must tell the Sequencer which 8K bank you will use ...

Maybe also some of these banks are just ROM (otherwise, having a silly loop that erases everything should also overwrite the fonts table and your character will be screwed up, which actually never occurs (afaik))