From: linstee@dutecaj.et.tudelft.nl (Erik van Linstee)
Subject: Re: FCC will proclaim Microsoft is run by Communists! : )
Organization: Delft University of Technology, Dept. of Electrical Engineering
Date: Fri, 25 Dec 1992 18:17:32 GMT

bai@msiadmin.cit.cornell.edu (Dov Bai-MSI Visitor) writes:

>In article <1992Dec25.102400.13417@donau.et.tudelft.nl> linstee@dutecaj.et.tudelft.nl (Erik van Linstee) writes:

>>Well, I don't know anything about your FTC, and I don't quite get
>>what it has to do with software needing to know about systems
>>internals.
>>All I am saying is that software engineers needn't worry about
>>system internals. Only time critical software needs to grab an
>>interrupt and as regular software goes this would only be a
>>comm. package. And even then the designer needn't know about
>>the internals, because he can use a library that installs an
>>interrupt handler. Of course he can prefer to do it himself, as
>>I often do, but that is only because I choose not to use anything
>>I don't have total control over. this is of course only feasible
>>if you design a piece of software by yourself.
>>Summary: application designers need not worry about system internals,
>>thats what the systems the designers are for.

>Does not the DOS programmer need to know about segment:offset 
>addressing, what memory model to use, and when ? Can one program
>effectively on DOS without that knowledge ?

No, one need not know about segment:offset. Why do you think they
should?
Yes, one needs to know what memory model to use when programming
in C, but only to optimise results. That is a feature C provides.
Programming in Pascal does not involve memory models. Anyway,
choosing the memory model is no programming decision, proper
code is not affected by memory model.
No, one can not program effectively for DOS period.

>How about the differences between 286/386 ?

Well, what about them?

>How about the 640k limit and how to overcome it ? Need not the 
>programmer know about extended/expanded memory, DPMI/VCPI interfaces ?

The 640k limit is of no concern. When you write an app. and you
need memory, you request it and check if you got it. You do not
consider if maybe the target system has a specific limit, you
just check for any limit to be reached. Either way you have to
alwayys consider a system running out of memory. On a 32M system
do you consider a memory limit? What if only 640k is still available?
Does that affect your programming? I think not.
No, a programmer needn't know about DPMI/VCPI interfaces. If he
wants memory, he requests it, he does not generally care where it
comes from. The DPMI/VCPI interface should be hidden from him,
unless of course he is writing his own memory management, but
I can't think of a reason why an application should need that.

>I have in front of me the second edition (1992) of the book
>"Extending DOS - A Programmer's Guide to Protected Mode DOS" by
>Ray Duncan. The first introductory chapter include detailed description 
>of selectors, descriptors etc. 

Protected mode DOS, where can you buy that? Oh wait, it says
Extending DOS. So it isn't part of DOS? Then it can't be of
a DOS app. programmers concern, can it? Looks like systems programming
to me, but I could be wrong.


Erik van Linstee   |   Delft University of Technology   |   I'll be back ... 
Newsgroups: comp.os.os2.advocacy