Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
Now that we know the logical sector, you might be wondering
how to get it to absolute sector so we can read it. Well
we use a few formulas to figure it out.
They are:
sector = ( logical sector MOD sector per track) + 1
head = (logical sector \ sector per track ) MOD number of heads
track = logical sector \ (sector per track * number of heads)
Note that this is integer division instead of floating point
division. And also Modulo math. If you can't figure this out
just turn on QBasic and enter a quick formula.
So. Using the formulas above we get:
sector= (34 MOD 512)+1= 17
head= (34 \ 512) MOD 2= 1
track= 34 \ (512 *2)= 0
Our file starts at Head 1 Track 0 Sector 17
The next sector Head 1 Track 0 Sector 18
The next sector Head 0 Track 1 Sector 1
and so on till the end.
My question is how can i implement modulo, i mean assembly doesn't have a modulo instruction. And mathematicaly modulo has many meanings. Please tell me is there a way to do modulo in assembly and if not can i do the above calculations without modulo?
i mean assembly doesn't have a modulo instruction. And mathematicaly modulo has many meanings.
Mathematically, modulo has one meaning: The remainder after dividing the two numbers. IIRC the assembly division instructions place the remainder into one of the registers.
When talking about computing, a mod b generally means the remainder when a is divided by b, which is (a % b) in c. For x86 assembly, after doing a div or idiv instruction the quotient will be in one register and the remainder in another, I think. Check the docs and see what you find.
As for uses of the word modulus (which I'm thinking is *not* interchangeable with the word modulo): mod x = |x| = abs(x). This use of 'mod' is pretty rare and is better refered to as "absolute value."
The only place I recall seeing the second use of mod(z) is for complex numbers, and most mathematicians will understand abs(z) so I stick to mod means remainder, abs means absolute. I don't think you will see mod(x) used to mean abs(x) used in any computing docs.
Too many words with similar names and different meanings, and too many words with more than one meaning. I have but a simple mind 