Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsd!sdcc6!sdcc10!cs163aeo
From: cs163aeo@sdcc10.ucsd.EDU (Professor I.R. Gumby)
Newsgroups: comp.sys.atari.st
Subject: Re: PC Ditto II -- speed?
Summary: PC Ditto II???
Message-ID: <102@sdcc10.ucsd.EDU>
Date: 4 May 89 21:37:58 GMT
References: <8905021217.AA08520@nh.cs.wm.edu> <98@sdcc10.ucsd.EDU>
Organization: University of California, San Diego
Lines: 59

In article <98@sdcc10.ucsd.EDU>, cs163afu@sdcc10.ucsd.EDU (Some call me...Tim) writes:
> In article <8905021217.AA08520@nh.cs.wm.edu> fjmora@CS.WM.EDU (Fredric Mora) writes:
> >In message dated 22 Apr 89 16:46:55 GMT, Ken Stailey writes:
> >> How much faster is PC Ditto II than version I. Does anyone know the SI rating?
> >The CPU-equivalent speed is said by Avant-Garde (THIS IS
> >THE RIGHT SPELLING!!) to be around 5 MHz compared to a 8086.
> >This gives an SI rating of more than 1.0. No info about disk speed,
> >although it is supposedly much faster than version 1.
> 
> This is not what I heard.
> 
> At the Anaheim Atari fair, Avant-Garde was displaying PC Ditto II,
> the hardware supported (NO processor, by the way, just hardware) IBM
> emulator.
> 
> It has a Norton rating of 3.0, and an equivalent speed of 10Mhz.
> 
> According to the person at the fair, PC Ditto II is in the "AT"
> class.

Define AT class machine.  Will PC Ditto II be able to execute 286
instructions?  Can I put it in protect mode?  Can I run *gasp* OS/2
with it?  How BIOS compatable is it?  An AT class machine is
something that not only is up to par with the AT on speed, but also
has the AT compatability.  The NEC V20/30 processors can execute
286 instructions, but they don't support 286 protect mode.  Does that
make a box with a V30 (which is significantly faster than a stock 8086,
average SI is about 2.7) an AT class machine?  Not by a long shot. 
One of the things that I find about these emulators is the
misinterpretation of what they can do.  My assumptions of an AT
class machine are the following: 

1. 80286 compatable CPU (right down to protect mode which directly
   implies extended memory support).

2. AT BIOS support (obviously, an XT 286 isn't an AT class machine),
   can I do the little trick of doing an extended memory block move
   with INT 15h, function 87h?  If not it's not an AT class machine,
   a lot of software that fakes expanded memory uses that crucial
   interrupt.

A caveat about emulators that everybody should be warned about is
this, they are only emulators, the emulator can blow up at ANY time.
And I'd be a bit weary about a machine with two different memory
addressing architectures.

Don't buy an Atari ST because it can run IBM PC software, buy it
because of what the machine can do on its own without any help
whatsoever from an emulator.  That's why when I bought my first IBM
clone a year ago over an Atari ST.  The programming languages and
utilities for an IBM are easier and less expensive than that for the
ST, so rather than take a compatability risk with an ST and PC
Ditto, I chose an IBM XT clone and later upgraded it to an AT
clone.  Now that Atari has the software I want (and now at the price
I want with Borland entering the ST market) and eventually the
networking hardware (if it's not out already, I am looking into
buying one.

 JCA