Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!brl-adm!umd5!mimsy!rab
From: rab@mimsy.UUCP (Bob Bruce)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Making overlays for BASIC or C
Keywords: overlays
Message-ID: <10265@mimsy.UUCP>
Date: 20 Jan 88 17:08:49 GMT
References: <305@stcvax.UUCP>
Reply-To: rab@mimsy.UUCP (Bob Bruce)
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 25

In article <305@stcvax.UUCP> rbh@stcvax.UUCP (Brent Haws) writes:
>Is anyone there out there that has knowledge of how to make
>an overlay file for an EXE file.  I have one that is getting large.
>OR is this even the way to go???

I have used overlays in the past, and they are NOT the way to go
in most cases.  Use the `exec' system call, and let the operating
system do the dirty work.

If you are using `C' then exec() is usually available as a library
routine.  You should also check out spawn(), if your library provides
it.

If you are using BASIC then you will probably need to write
a small assembly stub to make the exec call.  This is a little
tricky since the exec system call destroys the stack pointer.
You should save SS and SP in your code segment before invoking
the interrupt.

>Brent Haws   {hao ihnp4 decvax ucbvax!nbires}!stcvax!rbh   (303) 666-4297
>StorageTek Corporation, MD-3T, Louisville, CO 80028

 Bob Bruce
 rab@mimsy.umd.edu
 uunet!mimsy!rab