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%% Emulation Rambler                                  by  Jason Compton  %%
%% The A64 Package V3.0                            jcompton@bbs.xnet.com %%
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Things come full circle, I suppose.  About a year ago this time, I debuted
this column with a small review of three products.  One of them was The
A64 Package V2.0.  I won't bother repeating it here,  but I won't need to,
because A64 V3.0 is a very new and different product from its predecessor.

Background

Let's face it.  A lot of Amiga users, myself among them, are 64 converts,
who for whatever reason decided to stick with the Commodore brand name
when it came time for them to pick a more powerful computer.  I had told
myself that I'd still screw around on the 64 when I got the Amiga.  That 
didn't happen.  But I still had everything, including a software 
collection spanning 6 years of 64 use.  Shame to put all that to waste,
but inconvenient to have a separate computer system set up.  This is 
where emulators come in: space- conscious, and, if you're lucky, 
effective.

A64's premise

Questronix (well, Cliff Dugan, they seem to be one in the same) has put a
lot of work into making this thing run properly.  A64 is, just like a 
real 64, based around a BASIC and a Kernal ROM.  Because Commodore's ROMs
are copyrighted, though, and Dugan wanted the emulation available to 
everyone, he physically wrote his own ROMs for the A64.  (not a small 
task!)  However, for increased software compatibility, it is suggested 
that you pull the ROM images from a real 64 and have them on tap, just in
case.

A64 comes with a small beige box.  One end is a parallel connector, the
other is the 64's serial port.  To this, you can hook up any legal 64 
serial device (like a disk drive or printer) and use it in A64.  In 
addition, the 64 emulation can use the Amiga's serial and parallel 
ports, and can assign legal AmigaDOS paths as 64 floppies.

While A64 is running, the Amiga side is totally disabled.  However, the
emulation can be frozen, allowing access to the Amiga side, with the
keypress Alt-Alt.  (incidentally, the keyboard is emulated in a fairly
logical manner, unlike A64 1.0, which had users trying to reach the DEL
key for the Inst/Del key on the 64.  It resembled the 64 keyboard more
closely, but was horrible in practice.)  From here, quite a few things 
can be changed about the emulation: The way the screen and sprites are
displayed, how raster splits are being treated, and even a 64 monitor
mode can be entered.  There are also some very interesting options
here, the best being Save Map, but I'll get to that in a future issue.

Putting A64 to Work

So, when it's finally time to put A64 to work, let's say you've dug up a 
1541 floppy and have hooked it up.  There.  All set.  Now you have to 
find a piece of 64 software to put in it.  Once you start loading it, 
you can go over this checklist to make sure it will work (and believe 
me, you'll have time considering how long it takes the 1541 to load 
things)

1.  Does this program have a fastloader?
2.  Does this program have a copy protection scheme that's going to do
    nasty horrible things to my disk drive?
3.  Is this program a demo?

If the answer is yes to any of these questions, you can be fairly certain
that you're probably not going to get what you wanted.  Fastloaders tend
to kill A64, clunking copy protection often freezes up, and most demos
are coded with methods A64 isn't used to seeing.  (a friend of mine was
a demo/intro coder on the 64, and virtually everything he's written shows
up incorrectly)

Anything which is straightforward with no big graphical tricks runs just
fine: and in this there ARE games included.  However, one of the biggest, 
most often appearing graphical problems come with raster splits that
change character banks: if you know what I mean, great.  If you don't,
it means a trick that lets the 64 use two different sets of characters on
the same screen.  Usually, A64 only picks up on one or the other.
That means that part of the screen will look garbled, because what's
supposed to be there is data contained in another character set which
would have made it look pretty.

Navigating and getting stuff
-----------------------------

Of course, I spoke earlier about the A64 interface box, that allows you
to use 64 devices, and the ability to use AmigaDOS paths as disk drives.
You'll want to take advantage of the Amiga device capability, because
the speed difference is phenomenal (and you think 880k floppy drives
are slow...you'll BEG for them once you use a 1541 again for a time).
A program called 64Tools helps out here, allowing you to copy between
sides (WARNING: NON-MULTITASKING WHILE COPYING!) and doing various
manipulations to the files, particularly stripping the load address (two 
bytes at the start of 64 files).  The transfer is slow, but if the files 
are used often, the savings are well worth the trouble.  Using a modem 
to download files (a 64 term, of course) to the hard drive directly 
should be a treat as well.

Compatibility?
------------

I went over the basic rules earlier.  However, it is worth mentioning 
that A64 supports Isepic files with an included patch, and can support 
GEOS on 68000 machines ONLY.  I have not had a chance to test either, 
but will try to dig up a copy of GEOS to run on a friend's 500 soon.

Compatibility can really only be found on a case-by-case basis.  It is
my experience that any program, if it can load correctly, will run.  How
well it runs or how good it looks can be another story entirely, and 
depends a lot on how much the user plays with the graphics options.  
Using these options allows you to set screen refresh rates, sprite 
refresh rates, raster interpretations, color schemes, and more.  There 
are a LOT of possible settings, and finding the one just right for the 
game you've been wanting to play for 5 years may take a little time.

Next week, I'll talk about how to get more speed from the A64, and offer
a few more thoughts on the product.

Until then, keep the emulators warm.