I'm not sure that the leading zero is a requirement but I haven't used an assembler on Intel x86 much since the DOS days. I know that back in those days, I could use the instruction, "int 16h or, to make a DOS call, int 21h" without putting a leading zero ahead of the interrupt value. Of course, lots of the really useful interrupts 2 (single step), 3 (breakpoint) and 9 (keyboard) look the same in hex or decimal so they wouldn't matter if they had leading zeroes or not. If I remember correctly, Wordperfect prior to v5 for DOS had a hook for screen readers located at interrupt A0h but it has been an eternity since I looked at that while working on "Right Writer" a grammar checker for DOS. Alas, I grow more nostalgic as this thread grows... cdh -----Original Message----- From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Ian D. Nichols Sent: Wednesday, February 20, 2008 4:38 PM To: programmingblind@xxxxxxxxxxxxx Subject: Re: what is Hex? Hi, To add a little more to this topic, for the general inlightenment of those who don't already know: In Intel assembly language, a hexadecimal number must have an "h" at the end, an octal number must end with a "o", and a binary number with a "b". Without any of these, the assembler assumes the number is decinal. Further, a hexadecimal number that begins with any of the digits "a" to "F" must begin with a zero as well as ending with an "h", otherwise the assembler tries to interpret it as a label or variable. All the best, Ian Ian D. Nichols, Toronto, Canada ----- Original Message ----- From: "Jamal Mazrui" <empower@xxxxxxxxx> To: <programmingblind@xxxxxxxxxxxxx> Sent: Wednesday, February 20, 2008 1:43 PM Subject: Re: what is Hex? > By the way, I think someone said that a hex number starts with 0. I don't > think that's quite right. C derived languages typically distinguish a hex > number with a preceding 0x, but the number is what follows the x. Other > languages or contexts use different conventions to distinguish hex from > decimal, e.g., Visual Basic uses a preceding &h sequence and Unicode uses > a preceding u. In other contexts, the number is understood to be hex, so > no additional prefix or suffix is needed. > > Here is a long Wikipedia article on hex > http://en.wikipedia.org/wiki/Hexadecimal > > Cheers, > Jamal > __________ > View the list's information and change your settings at > //www.freelists.org/list/programmingblind > > __________ View the list's information and change your settings at //www.freelists.org/list/programmingblind __________ NOD32 2890 (20080220) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com __________ View the list's information and change your settings at //www.freelists.org/list/programmingblind