No one has answered my earlier question, (which I am still waiting an
answer for) heres a new question

I need an assembly language program that would input a string of
characters from the keyboard and print it in reverse order.
eg. if HELLO is input, then OLLEH should be the output

Assembly language is a vague term. Which processor do you need this
code for? x86? ppc? alpha? itanium? z80?

One possibility is to write code in C and compile using GCC. Tell the
compiler to output assembly code from your program (use the -S switch,
documented in the GCC manual).

I have a pentium processor. 
I want to be able to compile and use it using MASM

Thanks!

Why not just look at
http://moneycentral.communities.msn.com/AssemblyLanguage/general.msnw?action=get_message&mview=1&ID_Message=247
?  That takes care of the reversing step, which should be the hardest
anyway.

There's a little error when he says "Now that we have...the start in
cx" but he means the length is in cx, but other than that a quick
glance doesn't reveal any problems to me.