Advice on code

[Guest_imported]

Looking for advice on assembly language code. Want to know what code be needed to change a character (bet a-z, whether in upper or lowercase when typed in) into uppercase and then display it on the screen.

Any help much appreciated.

 

[mbaranski]

It is pretty easy. If I remember correctly, the ASCII Codes for capitol or uppercase letters differ by one bit (The shift key on the keyboard makes this bit a 1 to give a capitol) so all you'd have to do is figure out which bit it is, or the corresponding bit with a 1. That is, figure out which bit you need to change to get a capitol, and make it 1. For example -> This is made up, you'll have to find the ASCII Codes:

a -> 10011001
A -> 10011011

b-> 10011101
B-> 10011111

So, bit # 7 == on means a capitol letter, so to make a -> A, just do a or 00000010, which will result in A

Hope That Helps!

Mike B.

 

[mbaranski]

OK, I looked up the symol table on

http://www.december.com/html/spec/ascii.html

and, for example

Hex ASCII Char binary representation
46 F 01000110
66 f 01100110
45 E 01000101
65 e 01100101

So, if you have a letter, and you take the 3rd bit (From the right) and set it to 0, you guarantee that it is a valid upper case letter if you started with a lower case. You still need to check if it's in the range of lower and uper case letters, tho!