well this is just a little anomoly..(excuse the spelling). As I've settup my 8253 timer chip to 100hz.
E.g.
mov al,36 ; outb(0x43, 0x36)
out 43h,al
mov al,0xe9 ; default is 0x0000 (65536) (18.2 per sec)
out 40h,al ; out(0x40,countdown_lsb)
mov al,0xe8 ; msb
out 40h,al ; out(0x40 countdown_msb)
where the
1.19318/E9E8h gives us about 100hz or 100 times a second.
Now for test purposes I have all my interupts calling a single interrupt test function.....its only a test piece of code...does nothing but go into protected mode and set the timer chip then count the interrupts...now for every 100 times the interrupt is called, I poke a character onto the screen.
But it doesn't seem to be 100hz...does the timer chip call multiple interrupts?...as the counter 0...does counter 1 and 2 call interrupts irq?...which ones etc...as I know counter2 is audio?
Counter 1 is for ram refresh etc...but does this also cause an irq interrupt.
I mean I disabled all the interrupts except for irq 0.
e.g.
; Enable IRQ0 (timer) at the 8259 PIC chips, disable others:
;(Port 0x21 bit 0 is timer)
mov al, 0xFE
mov dx, 0x21
out dx, al ; outb(0x21, ~0x01)
mov al, 0xFF
mov dx, 0xA1
out dx, al ; outb(0xA1, ~0x00)
Its just strange that my timer chip is calling my interrupts at 1000 times a second or something.
Thanks for any ideas on this....any ideas would be great just of the top of your head would be great.
Thanks again
Ben