Can someone explain how this work?

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ASM

mov ah, 02
mov cl, 19
mov bh, 01
mov dl, 41
int 21
mov dh, dl
mov dl, 0a
int 21
mov dl, 0d
int 21
mov bl, cl
inc bh
inc dh
mov cl, bh
mov dl, dh
int 21
loop 011e
mov cl, bl
loop 010a
int 20

it has an output of
A
BB
CCC
DDDD
...
and so on up to 'Z'
i just need some explanation on cl,bh,and dh
thanks in advance and ill appreciate it if someone could explain it thoroughly

Posted 30-Jan-14 20:36pm

Member 10548351

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OriginalGriff · Answer 1 · 2014-01-30T21:25:00

No!
I for one am not going to: it's just too much work!

Instead, sit down with a piece of paper and a pencil, and create a bunch of boxes - one for each register being used. Then go through the code and fill in the boxes as the instructions execute and change the values.
Slowly, it should be obvious what your two loops do, and how each instruction contributes to that.

The thing is that if you understand the assembly instructions and what they do, it's pretty obvious. If you don't, then you need to - and the only way you will do that is to execute them yourself and see what happens. And "hand-cranking" the code is probably the best way of doing that.

To add to that, we don;t even know exactly where anything is: your loops are to absolute addresses rather than labels, so we would have to guess what is where - and guessing is not a good solution to any computing problem.

If you didn't understand it, why did you write it? And more to the point, how?

Richard MacCutchan · Answer 2 · 2014-01-30T21:47:00

Solution 2

I already provided an explanation, and pseudo code to solve the problem, at How Do I Get To Display This?[^].

Posted 30-Jan-14 21:47pm

Richard MacCutchan

Comments

Member 10548351 31-Jan-14 4:18am

believe me i tried it all night, trying to figure it out and putting it on assembler but no luck.
if you can give me a site or a tutorial video where i can learn about this cl,bh,and dh
ill be happy to learn it on my own

Richard MacCutchan 31-Jan-14 4:32am

There are plenty of sites that cover assembler programming, all you need to do is search for them.

Member 10548351 31-Jan-14 4:38am

okay thanks :)