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Alive 8

        Emulators under '060 considered..

I've  got  a  bit  of  spare time since kicking out  the  main  bulk  of  my
contribution  for this issue of Alive!  Seb hasn't had the chance to do  the
same yet,  so this gives me some extra time to introduce a topic which I had
sort of planned to leave until next time.

I've  always  been fascinated by the concept of emulations,  even since  the
early days.  The idea that one computer can emulate another, the other often
running  with a totally different design philosophy and hardware,  might not
do anything for some people,  but it rips the 'need to know more' part of my
brain  open like a rusty tin-opener with the audacity of the idea.  The idea
first took off properly when I got a Falcon '030, the first machine I owned,
which I considered as powerful enough to seriously attempt it.

There  were  some early successes,  such as Christian Gandler's 'Specci'  ZX
Spectrum  emulator,  which  did a pretty decent job of imitating  a  classic
early home computer,  which was a repository of many fond memories among the
UK'ers.  It  did  become apparent that the Falcon didn't have  enough  basic
processing grunt to get much further than that.  Others did try though,  the
most notable effort being the Reservoir Gods attempts at getting us to  play
'Nintari'.  But generally,  it was realised that a whole different magnitude
of hardware power was needed,  if emulations of any great complexity weren't
going to be agonisingly sl-o-o-o-o-w!

In  theory,  any  'Turing Machine' or computer can emulate another,  but for
that  emulation  to  take  place in  a  meaningful  time  frame,  preferably
realtime, the capability of the host machine has to be significantly greater
than  the  target machine.  To be painfully honest,  a 16mhz '030 wasn't the
ideal solution.

And  at last,  the hardware boost of sufficient power has arrived,  with the
CT60  accelerator.  People without one of these will be getting tired of the
triumphal tone of this paragraph, but it also serves as a useful opportunity
to  re-examine some of those classic emulations created with a TOS  computer
in  mind.  (It is interesting to note that no-one with a Hades or Milan '060
has written in previously on this topic,  but then again, it always seems to
take a scene-active Falcon owner to boldly step where serious users fear  to

The  emulators we tested were,  with one exception,  programs which were all
developed and abandoned years ago, in some cases, up to a decade ago. It was
going  to be interesting to see if anything did work with the most  powerful
end of line member of the MC68k family, or possibly not?

The  news  was somewhat mixed.  Some ran,  others didn't,   but there was one
which was very good.  I tested both with caches 'on' and caches off mode. It
didn't  seem to make any difference to stability either way.  So how did  we
get on?

Specci 2.07 was compiled with a Falcon/TT combination in mind. This 1993 era
emulator  has  worn  amazingly  well,  and  offered a  very  high  level  of
compatibility for back then.  When it was introduced to the new hardware, it
ran,  but not for long,  as a wobble of instability was introduced.   Specci
could go a short way,  but then it crashes within the emulator, generating a
Specci-specific  error screen.  At the same time,  you find that a reboot is
needed because the CT60 as a whole is frozen...

Sander Berents TRS80 emulation managed to run. This mono-based GEM emulation
was too fast even on a CT2.  The same went for it on the CT60.  The keyboard
emulation  was  unstable,  throwing up jittery extra unwantedd  charactersss
with a lot of keyyy presses.  Any games ran way too fast,  but I was able to
leave the building safely and quit the application.

Another personal favourite of mine was Christian Peppemuellers 'AtOric' Oric
emulator,  which was almost there, but not quite, at version 0.9. This seems
to want to start up, but it locked up and froze on the boot screen.

Patrice Mandin ported over 'GnuBoy' to Atari TOS and compatibles.  Should  he
have  bothered?  Even  with the '060,  this was still horrible and slow,  and
looks and sounds very ill!  I guess this is a totally unoptimised port,  for
which  we  are awaiting the Atari Coldfire project to run  in  a  meaningful
manner.  Or  perhaps  Rodolphe  Czuba is planning an Intel  'Prescott'  4ghz

As for Stemboy, the generic GEM Gameboy project taken over by Matthias Jaap,
managed  to  start up okay,  but it crashed when you attempted to run a  ROM
image.  This  is  identical  to how it behaved before on my Falcon  and  CT2

Ed  Cleveland might well give us a ghostly smile of recognition,  if he ever
reads  this,  as  his  STe-based 'Nesulator' NES project at last runs  at  a
useable speed!

In contrast,  Godboy and Godlenes crash and burn horribly for the most part.
Although one or two of the earlier Godboy games run, (Bubble Bobble) but not
showing any significant speeding up effect.

The  ZX81 emulator works flawlessly and is very stable in operation.  It  is
very much on the fast side,  but not ridiculously so.  I would say it thinks
it is running on a very fast 68000?

The  one  I tried the most,  before any of the others,  and over the longest
period of time was Flaysid. I can categorically confirm that this one works!
It  is rock solid in operation.  It is still very much dependent on the  DSP
speed for quality of playback,  so it will play the higher 33mhz replay rate
better if the CT60 bus is boosted to 20 or 25mhz.

(On  the theme of music players/emulators,  'Jam-GEM' does work,  but you do
have to turn the caches off first..)

I've  saved the best to last,  which is also the sole emulator project still
currently under ongoing development. This is the Petr Stehlik inspired Atari
800  emulator.  It  was always too slow previously,  even with a  reasonable
accelerator  like the CT2,  but with the '060 it comes into its own at last,
and runs at a speed more or less resembling the real thing!

I've  switched  between three distinct versions of the  beast,  v1.2,  which
offers  the  best  speed.  Then there is the current version 1.3,  which  is
slower,but has slightly better music replay, and a greater range of emulated
extended memory (up to 1 meg!) Finally,  we have the 68k assembly version of
1.3,  which was a lot less stable than the others, and didn't show any speed
related  benefits  on the '060,  in spite of being described as the  quicker

Atari  800 was able to run most demos at a speed which was 100%,  or in some
cases  on  v1.2,  slightly faster.  If you have a desperate need to view old
school scrolly demos c.1989 on a CT60 boosted Falcon,  then Atari 800 may be
your  best bet.  There is a superb demo archive at the following location:-

I'm working my way slowly through the collection at the moment! On the disks
there are a number of classic 8-bit demos,  such as 'Drunk Chessboard',  and
the  more recent 'Te-Mod' by Satantronic.  These run very well under a  CT60
boosted  Atari.  Plenty  of old demos also run,  and the few modern Taquart-
style demos with swirly effects I've so far seen also work beautifully too!

            Plasma is so relaxing!

Where Atari 800 gives the impression that it is a somewhat broken Atari  800
or XL series machine,  gamely attempting to do its best but not quite making
it, is with the sound emulation. Pokey does replay back at the correct speed
on  v.1.2,  but with lots of crackles and popping.  Any major excursion into
digisound tends to crash (as in a proper CT60 exception error 2 debacle)  or
freeze the emulation altogether.  This is the case on all versions! In other
words,  Atari 800 will run most demos decently,  but be prepared to reboot a
lot  when  you find one that upsets it!  I've not tried any games  or  other
applications yet,  but I would assume that there would be more stability, as
these make far fewer outrageous demands on the hardware.

To  be fair to the CT60,  I did also roadtest Atari 800 simultaneously on my
CT2  machine,  and the general stability level,  with occurrences of locking
and  freezing etc,  were about the same there.  I also noticed a much slower
emulation speed on that platform as well.

If  Petr,  or anyone connected with the Atari 800 project are reading  this,
can they incorporate an easy way to disable the POKEY part of the  emulation
if  required,  as I'm pretty sure that is behind most of the crashes that we
do get at the moment.

             You want it oldskool?!

To end this article, I've got some suggestions for future emulation projects
that could be viable for the CT60 level of hardware, if anyone can be minded
to do them of course ;-)

I've  ranked  these  in order of plausibility and  likely  effort  required,
starting  with  the ones that should be easier to do.  My  first  suggestion
would  be for a new Speccy emulator.  This would preferably include the 128k
Speccy,  and possibly some of the weird Russian clone versions. With an '060
inside, porting existing higher language code becomes a real option now. The
CT60-ised  Falcon has some built-in advantages,  as some hardware (YM sound)
is already present and won't need emulating. The rest of the Speccy hardware
is  relatively  uncomplex,  with no major custom chips.  Maybe the  intrepid
emulator porter could attempt an Amstrad CPC6128 on existing portover  code?
This  later machine has more complex hardware than the Speccy,  but not much
more so, and certain common features, (YM sound, and a Z80 CPU.)

At  a  middling level of difficulty are machines such as the  Commodore  64.
This  could  be portover from any existing Amiga code?  The  DSP  SID-engine
already exists in more than one form.  It is even said that Flaysid is a C64
emulation,  with  the  C64  ROM and 6502 emulation included,  albeit it  all
concentrates on the sound system,  ignoring the rest? But contact from David
Carrere is very intermittent,  and the release date of any future Flaysid is
uncertain, let alone him doing anything else from there? It is arguable that
the  already accomplished Atari 800 is a more technically complex system  to
emulate  properly,  but it has been done,  so a C64 would be well within the
abilities  of CT60 to do well.  (On a related note,  we are still waiting on
Oliver Heun's attempt to emulate the Plus 4 series.)

I would also like to know whether there will there be any further  Reservoir
Gods  inspired   ports  or patches of their NES and Gameboy  stuff?  It  was
optimised  and  adapted  heavily to work on the  standard  Falcon  '030.  It
reached an apogee of performance on the CT2,  so perhaps it would be far too
quick with the CT60?

In  the realms of the challenging but feasible comes the classic Amiga  500.
In this case, we have a CPU family in common, and some of the hardware, such
as  the Paula soundchip has already been done.  The graphics are within  the
current  Falcon/CT60  capabilities.  I would guess we would  be  using  disk
images for the otherwise non-standard disk format?  If someone was motivated
enough,  it would be a suitable revenge to take on those snotty Amiga owners
who think Atari is nothing but lame!

Now  we are at the outer limits of the possible.  We would be looking at the
16-Bit generation of consoles.  The Sega Megadrive has got the CPU family in
common (68000). The sound hardware would be tricky to emulate and would need
a  very dedicated DSP wizard.  And we have got to see if the CT60 can  carry
the screen hardware emulation properly?

The SNES would be a major challenge.  It would be great if this one could be
pulled  off.  There would be lots of work to do in all areas,  with its very
custom hardware it would take years to get it right and optimised. I seem to
remember that the Reservoir Gods were pondering this for the Phenix  project
at one point.

And finally,  I've got a silly suggestion.  This is a decent ST emulator for
the  Falcon  or CT60.  Or at least a rework of  'Backwards' to load and  run
.MSA disk images off CD-ROM or other mass storage device.   There has been a
proliferation  of games/demos collections using that media and  format.  Why
should  PeeCee  ex-ST owners have all the convenience,  whereas we who  stay
faithful to the next generation of the original hardware, are left rummaging
in  depleted blank floppy disk storage boxes to go through  endless  copying
hassle and tedium?

Or even a simple .msa bootloader for ST/Falcon and whatever external storage
device combination might be enough?

Sorry, got off the topic and onto a personal wishlist thing there.

Okay, see you all next time.

CiH, for Alive! Mag,Feb '04.

Alive 8