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From: mmshah@athena.mit.edu (Milan M Shah)
Newsgroups: comp.os.msdos.programmer
Subject: TASM can't subtract ...
Message-ID: <1991Mar1.014835.7651@athena.mit.edu>
Date: 1 Mar 91 01:48:35 GMT
Sender: news@athena.mit.edu (News system)
Organization: Massachusetts Institute of Technology
Lines: 42

Hi!

I am trying to assemble Fontedit.asm, a program published in PC-Magazine
vol 7 no. 15 using Turbo Assembler 1.0 (Yup, its 1.0 alright). In the program,
there's a couple of lines that go:

LOADER 	LABEL	BYTE
LOADER_OFFSET	EQU	100H - LOADER

Simple enough, but TASM complains. It says 'Can't add relative addresses.'
First off, 100H is a constant, and not a relative address. Second, I think
its pretty ridiculous for TASM to give an error and die. Maybe a warning,
but to refuse to assemble? Sheesh, here's a number, here's another, and I
want TASM to subtract one from the other, and TASM can't do that? That's
ridiculous, I sez. So I try:

LOADER_OFFSET	EQU	100H - $
LOADER_OFFSET	EQU	100H - OFFSET LOADER
LOADER_OFFSET	=	100H - [each of three options above]

In all cases, TASM complains. It does so even in QUIRKS and MASM mode.

So, I gave a call to Borland on my dime. The semi moron at the other end
wanted an explanation as to why I wanted to do the above. He kept stumbling
on (you know, the answer will probably be negative (Wow! brilliant)), and I
kept asking "So?". I finally had to hang up after ~25 minutes when I realized
that for the price of the call, I could probably pick up a copy of Microsoft's
assembler off the net!!

In any case, since I have already spent the money on the product and more on
entertaining a clown, can anyone suggest a way out? The only solution I know
of (and it semi-works) is that everywhere I want to use LOADER_OFFSET, I have
to first subtract off OFFSET LOADER and then add in 100H. I have no objection
to doing this, save for the fact that LOADER_OFFSET is used in other Equates. 
It bugs me no end that TASM can't subtract two numbers which are completely
and unambiguously defined, and I paid a cool $259 (for the professional C)
package for this. :-(

Thanks for any help!

Milan
.