Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!hao!oddjob!mimsy!rab
From: rab@mimsy.UUCP (Bob Bruce)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: Looking for C functions to access PC memory
Message-ID: <9305@mimsy.UUCP>
Date: Wed, 11-Nov-87 17:08:37 EST
Article-I.D.: mimsy.9305
Posted: Wed Nov 11 17:08:37 1987
Date-Received: Sat, 14-Nov-87 05:56:51 EST
References: <24261F3U@PSUVMB> <447@ucdavis.ucdavis.edu> <261@grinch.grinch.UUCP>
Reply-To: rab@mimsy.UUCP (Bob Bruce)
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 23
Keywords: Using pointer in C
Xref: mnetor comp.sys.ibm.pc:10035 comp.lang.c:5380

Followup-To:


In article <261@grinch.grinch.UUCP> luis@grinch.UUCP (Luis Chanu) writes:
>In article <447@ucdavis.ucdavis.edu> kwok@iris.UUCP (Conrad Kwok) writes:
>>	...
>>	ptr = (char far *) 0xC0000100L;
>
>  1. Why is there an 'L' at the end of the address?  (does it stand for Long?)

Yes, it stands for long.  Many compilers have 32 bit pointers and 16 bit
int's.  Appending an `L' to a constant is equivalent to casting it
to a long.  In an assignment, such as this, the `L' is not necessary,
but it does emphasize that the constant is bigger than an int.

>  2. I have been trying to access the DTR on my modem, but I don't know
>     what the base address is.  From the Technical Reference, I know that
>     the offset is 3FE (bit 0), but can't find the base address.  Can anyone
>     help?

Sorry, but the 3FE is a port address, not a memory location.  Check your
compiler manual.  It should provide some library routines for accessing
I/O ports.  Usually something like `outp()' and `inp()'.

If these are not provided then you are going to have to write some
assembly language routines.