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ATARI 800 EMU V1.0


                       David Firth/Petr Stehlik

This is probably one of the most incredible pieces of software ever to hit a
Falcon hard drive.  Very simply put, it is a more or less complete Atari 800

How is this so?  Well, we have the persistence of David Firth, who started a
portable cross-platform freeware 8-bit emulator for the old Atari.  And Petr
Stehlik, for taking the time to make it work on his Afterburnered Falcon.

There  has been a lengthy history of trying to get the venerable 800  series
to work on succeeding Atari hardware. Even from the earliest days of the ST,
where  the  programmer of GEMulator decided he wanted to transport  some  of
that 8-bit magic across to his whizzy new 16-Bit ST.

I've never seen or tried out the end result, but I believe it did quite well
within  the  limitations  imposed on it by the ST's  hardware.  Which  meant
almost  nothing that needed any exotic graphics modes or dabbled too  deeply
into machine language,  could actually run. The problem was, that the design
philosophy  for  the different generations of Atari hardware  were  too  far
apart from one another.  The 800 having more in common with the Amiga,  with
its various custom hardware, and indeed having the main designer, Jay Miner,
in  common  too.  The  ST,  which influenced succeeding generations  of  TOS
computers,  was  more  'off the shelf' in its conception,  and less flexible
than the 800, in some respects, for all the extra CPU power it had.

It  really  took a few more years of hardware evolution,  for the new  Atari
generation to start to catch up with the Atari 800 ;-)

The  next best chance came with the Atari Falcon,  which cranked up the  CPU
power  a  bit more,  and also managed to break free of the  miserly  sixteen
colour onscreen graphics limitation.  Which is almost where our story starts
to come up to date.

They  soon found out although the Falcon had more to offer in  the  hardware
stakes,  it still wasn't really an ideal platform for emulation,  especially
as  it  was mainly CPU dependent,  like the ST,  and what custom hardware it
had,  such as the DSP,  could not help too much in this sort of case (except
maybe  for  sound emulation.) It also wasn't really (hand  on  heart!)  fast
enough for the job.

Some people took things further,  and spent serious money, acquiring serious
levels  of  CPU power.  In a brief exchange of email with Petr  Stehlik,  he
advised  me  that  the Afterburner '040 still was only able to  hit  40%  of
normal  speed for the 800XL!  - It may be the case that coding optimisations
have improved matters since then, but the fact remains, this is not an ideal
solution for owners of standard unaccelerated Falcons!

In  the  meantime,  I had managed to do a bit of catching up,  purchasing an
accelerator, which was not quite in the Afterburner class, but represented a
vast improvement over a standard Falcon,  the Centurbo 2,  which you are all
sick  of hearing about by now!  It was time to re-examine this beast,  which
now stood at version 1.0.

The  download  unzipped to a .gtp file,  activated by drag n' drop,  various
ROM's,  a MYDOS disk image,  loads of doc files,  some of which going into a
lot of detail, and a config file, to make sure it all ran together smoothly.

To run it,  it is firstly a good idea to switch to a 256 colour screen mode.
Hi-res  VGA is perfectly acceptable,  if you like to look at an 800XL screen
in a small centralised window that seems some distance away ;) It is  really
better to switch to a lo-res or 'double line on and 40 columns' mode, to get
a  fully  authentic screen experience.  A short pause,  and the familiar sky
blue with white text main menu of MYDOS comes into view.

A useful key to remember to press at this point,  is F1, which brings up the
control menu for the emulator,  whilst it is running. Disk management, which
lets  you  select  disk images and assign them to any one  of  up  to  eight
connected  virtual floppy drives.  There is an option to run a program  file
directly,  if that is stored on your Falcon.  (These come in various formats
often  as *.com files.) A very useful sub-menu lets you select the  type  of
emulated 8-Bit you want to work with,  including classic bog-standard 800XL,
the later 130XE,  even a couple of different memory upgrades to Atari 320XE,
and the Atari 5200 console, based on the 8-Bit hardware.

Various others round up,  including warm and cold resets,  and the chance to
leave  if  you  have  to.  The  keyboard shortcuts  for  all  of  these  are
prominently advertised.

It  is perfectly possible to go in through the MYDOS portal at  this  stage,
staring  in  admiration at the options available,  most of them  not  easily
understandable  to first time users.  Or it might be a better idea to go and
grab some disk images.

I'll  give  you a nice URL at the end of this article,  to go and  get  some
demo's  on  disk,  for  that is the real true test of how good  an  emulator
really is. Will it run everything thrown at it, or will it gasp and splutter
at the merest hint of anything system illegal?

I  am  happy  to report,  that this emulator breezes the  vast  majority  of
demoware,  even  coping  with  the  newest  ones.  This seems  to  bear  out
favourable  reports for this emulator (in its DOS or Linux  incarnation)  in
the  emulation  scene,  as  it  is seen to emulate  the  hardware  extremely
accurately,  even  being  capable of screen modes and tricks that  no  other
emulator can cope with!

The important issue is speed, or the lack thereof. From my testing on a CT2-
based  Falcon,  it  feels  as if this emulator is running at around  50%  of
normal system speed.  I say "feel", without having any benchtest software to
properly  assess  it,  and  basing that "feeling" on how the  screen  update
looks, which "feels" about half as quick as it should be!

I  did  try  a couple of games,  and the impression is similar to  an  early
version of Godboy on a standard Falcon, slow, but just about playable.

There isn't a lot of sound around.  In fact,  on the main *.GTP, there isn't
any.  There is a faster and buggier version,  with POKEY emulation, but this
has a nasty habit of stopping working,  a short time later, and the music is
played back sluggishly and out of tune as a result.

That  aside,  serious  bugs  are rare.  There is the odd program file,  that
upsets  things  completely,  but  it isn't clear whether that is down  to  a
weakness in the emulator, or poor setting-up of the memory configuration, as
I  seem to recall some 8-bit demos at the SV2000 needed  extensive  fiddling
with memory banks on these machines, before they decided to work.

The  other interesting point,  is that recent versions of the emulator  have
been coded in a 'system clean' sort of way,  which means that Milan and fast
TOS  clone users might be able to get some sort of benefit from it?  I  also
await  the arrival of some real computing power,  in the form of the  CT060,
the first viable '060 based accelerator for the Falcon.  Then we'll see what
happens next!

In  conclusion,  the  work  put in by David,  Petr,  and others represents a
considerable  technical achievement,  in emulating so completely,  a totally
'alien' system on an Atari TOS machine.  It was kind of interesting to run a
demo  (Drunken Chessboard) parts of which a normal ST (or Falcon?) would  be
apparently  unable to cope with!   It is an excellent piece of software,  if
you  own an accelerated Falcon,  as it is workable,  but just too slow for a
standard  machine.  It  is  one which should 'grow into'  any  future  Atari

I look forward to a full-speed version with POKEY Sound, on a CT060!

Dead Hackers 8-Bit demo anyone!!

Right, it's URL time for those people who are interested.

To  get  the latest version of the emulator,  in Atari,  DOS and  Linux

To grab some nice demos on disk images, try this one:-

If you hate typing in strange URL's, pick up the links from:-

To get these images to load, make sure you grab the 'menu.atr' file and have
it handy. Drag and drop the 'menu.atr' on the main *.GTP program.

A screen, which is almost blank, apart from the title 'yogi/jellystone park'
at  the  top,  then  appears.  At  this  point,  hit F1,  then  select  disk
management, put the cursor over D2, the first empty virtual drive, hit enter
and  select your disk image (Important - Leave 'Menu' where it is  in  D1!).
Hit  enter  again  and  escape to return to the  main  menu.   Then  'Select
system', and once that is done, press for a warm reset.

You should have a screen which has a couple of columns of demo titles,  with
a letter alongside it.  Pressing the corresponding key then loads that demo!
Easy,  isn't it! (Hint, most of these mega-images have more demos than first
appear onscreen,  press the down arrow/cursor key to get to these additional

CiH - For Alive! - Oct '00

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