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From: grunau_b@husc4.harvard.edu (justin grunau)
Newsgroups: comp.sys.atari.st
Subject: Re: ST-MS DOS Emulator
Message-ID: <867@husc6.UUCP>
Date: Thu, 11-Dec-86 17:25:43 EST
Article-I.D.: husc6.867
Posted: Thu Dec 11 17:25:43 1986
Date-Received: Mon, 15-Dec-86 20:04:23 EST
References: <8612110915.AA24407@ucbvax.Berkeley.EDU>
Sender: news@husc6.UUCP
Reply-To: grunau_b@husc4.UUCP (justin grunau)
Organization: Harvard Science Center
Lines: 44


In response to BO628524@CCNYVME.BITNET, I can say a number of things about
the paradox software emulator.

First of all, I wish to stress that the emulator is BY NO MEANS nor by anybody
I am aware of (least of all paradox) claimed to run at anywhere near 100% the
speed of an 8088 (whatever that means:  an 8088 running at what MHz, for
instance?).  Basically, it has two modes, one of which is more fully clone-
like than the other.  The non-fully-clone mode is supposed to run at about
70% the speed of an IBM PC, not even an XT.  (so, yes, it would be faster
than a PC jr.);  the clone mode is supposed to run at more like about 20% to
30%, if I remember properly.

I have never been totally sure what the difference was, except I know it
involves at least the difference between direct screen writes of characters
and direct screen writes of graphics.  Apparently, direct screen writes are
done by an enourmous amount of MS-DOS software:  more than you would imagine.
And the graphics are fairly easy to emulate, whereas the character data
(this is by word of mouth of the guy who programmed the emulator, who is
quite willing to converse at length over long-distance with total strangers)
has to be simulated, since of course direct writes of character data involves
writing no more than an ascii value to memory, whereas to plot the character
we need to write the bitmap to memory.  I am not sure why this would involve
such a huge drop in speed, when of course the ST OS provides means of writing
streams of ASCII bytes that will be turned into bitmaps, so I don't see why
it is any slower than the ST writing text;  but if the people who market the
emulator say that it can run as slowly as only 30% the speed of a PC, I
think we have no reason to doubt them, since it is hard to imagine anything
running THAT slowly.

Lastly, on the price:  the emulator is sold at the low price of approx. $69
ONLY if you also buy the 5.25" floppy drive that Paradox sells with it.  It
goes for the average 200 and some tens.  In fact, the author told me they may
ONLY offer it with that drive.  The system has to be booted off such a drive,
though you can store the MS-DOS files on an Atari hard disk partition and run
your programs from the hard disk.

Oh, and I don't see why Atari would worry about competing with a software
emulator.  Hardware and software emulation are two different worlds:  two
different price brackets and two different types of performance;  I see no
plausible source of competition...


									JJMG