djb@wjh12.harvard.edu (David J. Birnbaum) (09/28/88)
I am a novice 8088 assembly programmer trying to write an overlay for XyWrite (word processor). The manufacturer sent me a sample dummy program and explained what information is passed in what registers to the overlay. Apparently, the overlay manager is already built into XyWrite; if I write my overlay and call it HYPHEN.OVR (it's a supplementary hyphenation routine) XyWrite will know when to call it. I would be grateful for advice on how to assemble and link this type of overlay. I know how to produce .OBJ, .EXE, and .COM files, but how do I produce an independent overlay file? I can email the dummy program (it's only about 20 lines) along with the information from XyQuest (about one page) to anyone who would be willing to offer advice. Please email replies to djb@wjh12.harvard.edu (Internet) or djb@harvunxw.bitnet (Bitnet). If there's a lot of interest I'll post a summary; otherwise, let me know if you'd like a summary by email. --David J. Birnbaum
rzahavi@gateway.mitre.org (Ron Zahavi) (01/10/89)
I have a question regarding overlays. I realize it's not something
commonly used so I hope someone has some experience with it. I am looking
for a reduction in memory as well as disk space. After trying the
microsoft linker, it seems that it places the overlays (and overlay
manager) in the same .exe file, making it even larger. I have
noticed that many programs have .OVL extensions. It seems that these
have smaller .exe files and a better breakdown in size of their other
overlay files. This is the result I am after, since it allows you
to have a huge program placed on more than one 360k floppy while
moving it between hard disks.
Are these .OVL files commonly found only in the Pascal environment?
(I am using C). Are these really EXEC files and not overlays
in the true sense of the meaning?
Thanks for any info.
-- Ron --
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Ron Zahavi (703) 883-5637 Mitre Corporation
rzahavi@gateway.mitre.org 7525 Colshire Drive
McLean, VA 22102
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