Loadstar 224/224.d81/t.e2

Text File | 2003-01-01 | 13.6 KB | 506 lines

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 A B O U T   E M U L A T O R S   I I
          by Professor Dredd
           aka Ken Kill, Jr


IMAGE FILES

    You probably know that C-64 tapes,
disks and cartridges don't work on a
PC. To get C-64 data onto a PC hard
drive, you need method of encoding the
data. The emulator must be able to
recognize and decode the data as a
C-64 program. That's what images are
all about.

    For the most part, an image is a
byte-for-byte duplication of actual
data taken from a piece of C-64 media.
This media may be a C-64 tape, disk or
cartridge or even a ROM chip from
inside the computer. Some image files
contain additional header data telling
the emulator what's in the image and
how its organized. The technical
details of the various image formats
and their respective header data can
be found in the document "FORMATS.ZIP"
by Peter Schepers. Obtain this file
at:

       http://www.fairlight.to/

    The creation of image files and
the process of transferring them
between the C-64 and PC are topics
worthy of their own articles. See your
emulator docs as well as the above web
site for some helpful info and tools.
Also check out the newsgroup:

 comp . emulators . cbm
 http://groups.google.com

Some image files are included with
CCS64. These include:

 Kernal.rom - Binary image of the
   Commodore 64 KERNAL ROM taken from
   $E000-FFFF

 Basic.rom - Binary image of the
   Commodore BASIC 2.0 interpreter ROM
   taken from $A000-BFFF

 Char.rom - Binary image of the C-64
   character fonts taken from
   $D000-DFFF

 C1541.rom - Binary image of CBM DOS
   V2.6 1541 taken from $C000-FFFF of
   the 1541

 CCSMon.crt - This is a cartridge
   image. It contains a machine
   language monitor you can use with
   the emulated C-64. It behaves very
   similar to a HesMon cartridge
   plugged into a real C-64.


ROM IMAGES

    You never have to worry about the
KERNAL, BASIC and Character ROM's. As
long as they're present in the CCS64
folder, the emulator will function
correctly. It is possible to replace
these images with alternate ROM's, or
even customize them yourself. You can
download some alternate ROM sets from:

ftp://arnold.c64.org/pub/ut ils/roms/

    You could write a new operating
system for the C-64. If you assemble
the OS and copy the binary (object or
executable) code to a PC formatted
disk and name it with a .ROM
extension, you can use CCS64 to test
it. If you want to run the new OS on a
real C-64, burn it into EPROM and plug
it in!

    Such a custom OS need not include
a BASIC interpreter. You could create
any sort of environment you like to
compute in such as LINUX or CP/M! Of
course, this would be an ambitious
project indeed, and would require an
extensive knowledge of the C-64
hardware. I.E. you'll have to write
all your own drivers for keyboard,
video and disk/tape I/O. Then again,
you can borrow as much of the original
KERNAL as you like and make any
necessary modifications as you go.

    Some simple customizations which
don't require writing an entirely new
OS might include:

- new startup colors.
- new character font sets
- custom startup text (e.g. "WELCOME
   PROFESSOR, SHALL WE PLAY A GAME?")
- enhanced BASIC functions for GET#,
   INPUT or other commands
- added BASIC commands like MODulus,
   GRAPHIC, PLOT (ever wish "Simon's
   BASIC" didn't tie-up the cartridge
   port?)
- fast I/O routines for disk/tape
   (most alternate ROM's include
these)
- built-in DOS wedge or BASIC
   7.0-style DOS commands
- C-128-style autobooting from drive
   #8
- anything you can imagine!


CARTRIDGE IMAGES

    CCS64 includes CCSMon.crt as a
convenience for ML programmers. It can
be handy for tweaking programs that
don't fully function on the emulator,
or for breaking into a game to add
cheats (e.g. infinite lives,
invincibility.) You can get other cart
images from:

  ftp://arnold.c64.org/pub/games/
  Cartridges/

Using a cartridge image with CCS64 is
the equivalent of physically plugging
a real cart into a real C-64, and you
should think of it that way.
Cartridges are supported by the
current release  CCS64 2.0b, but not
on older versions. Check the manual
accompanying your version for
details.

    From the C-64 screen, hit ALT-C to
go to the "Cartridge" menu. Here you
see various functions which control
the operation of the emulated
cartridge port. Highlight "Insert
Cartridge" and press F1. Now you see
the "Insert Cartridge" file menu. PAY
ATTENTION because all the file menus
in CCS work the same!

    The first entry, ".." is used to
go up one level in the directory
hierarchy. Below that is a list of
files in the current directory. At the
bottom is a list of all drives
currently active on your PC such as
A:, C: and D:

    If you're not already inside the
CCS64 folder (the one you unZIPped
CCS64 into), you'll have to navigate
there. On my own PC it is located in
"C:{CBM--}Program Files{CBM--}CCS64{CBM-*}32". Hit ENTER
on a directory name to go down into
it. Hit ENTER on ".." to go up one
directory level. Hit ENTER on a drive
letter to change to a different active
drive.

    Inside the CCS64 folder you'll see
the image "CCSMon.crt". Highlight it
and hit ENTER. Now CCS64 restarts the
emulated C-64 with the cartridge
inserted. You'll see the CCSMon
startup screen.

    Now remove (un-insert) the
cartridge by pressing ALT-C to return
to the "Cartridge" menu. Use
down-arrow to highlight "Cartridge
Emulation" and right-arrow to select
"Off". Press ESC to return to the
emulated C-64. What the?!? The CCSMon
screen is still displayed! Hit ALT-R
to clear things up.

    ALT-R simulates a software reset
like SYS 64738. You can do a
hard-reset using ALT-SHIFT-R.
ALT-SHIFT-R simulates a reset button.
In most cases, just using ALT-R will
work just fine.


RAM EXPANSION

    From here on in I'll assume you're
comfortable with how the CCS64 menus
work and can select functions and
sub-menus on your own. If you have
difficulty, refer to the CCS64 manual.

    Another cool feature available
from the "Cartridge" menu is the "RAM
Expansion Unit".  This simulates a
Commodore 17xx REU. Here you can turn
the REU on or off, which is the same
as inserting or removing the REU. You
can also set the size of the REU
anywhere from 128 Kilobytes to 16
Megabytes using the "Size" function.
Imagine what you can do with a 16
Megabyte Commodore 64!

    Additionally, the "File Enable"
function allows you to preserve the
contents of the virtual REU between
sessions. When you quit CCS64 (ALT-Q)
the contents will be saved in a file
on your PC hard drive. The next time
you start CCS64, the REU contents will
automatically be reloaded (assuming
you leave "RAM Expansion Unit" set to
"On".)

    The cartridge port emulation of
CCS64 is superior to the same port on
a real C-64 in that you can keep the
REU enabled even when using other
cartridges (e.g. CCSMon.) You can
think of this as having a switched
dual cartridge port expander plugged
into the C-64 (similar to the
"Aprospand-64").


TAPE IMAGES

    There are two types of tape images
available for C-64 emulators. They use
different principles, but you don't
have to know the technical details
since both work just as well on CCS.
They are .T64 and .TAP files.

    From the CCS main menu (F10)
select "Tape Device 1". Now use the
file listing to navigate to the
drive/directory containing the tape
image file. Select the tape image you
want and press F1 to "Examine" it. CCS
has now inserted the tape into the
virtual tape drive.

    Here is something new. Tape images
can contain more than one C-64 program
or data file (just like a real C-64
tape.) The menu displayed at this
point allows you to select a program
from the virtual cassette to LOAD and
RUN it. Highlight the desired program
and press F1. CCS will now reset the
emulated C-64. The command LOAD "",1
will automatically be entered. In a
short amount of time the program will
have loaded and it will automatically
RUN.


PROGRAM IMAGES

    A program image is simply a C-64
program as it exists in the C-64's
memory. Typically this will be a BASIC
program, or a machine language program
with a BASIC startup (e.g. 10 SYS
2061.) These files are identified by
their .PRG extension.

    You can make a .PRG image file by
SAVEing a BASIC program to disk and
copying the resulting file to a PC
formatted disk. Then rename it with a
.PRG extension. Note that this is the
same procedure used to make a .ROM
image file. The only difference is
that .PRG files ALWAYS should have a
LOAD address of $0801.

    You can LOAD and RUN .PRG images
using the same procedure as for tape
images, right from the "Tape Device 1"
menu.


DISK IMAGES

    Disk images are a byte for byte
image of a 1541 floppy disk. They come
in a few flavors, but the most common
is .D64. You'll also run across .X64
and .G64. The latter is a GCR image of
the disk containing not only the data
blocks but also the header block and
low-level formatting info.

    From the C-64 screen, hit ALT-8 to
go to the file select menu for "1541
Device 8". Navigate to the
drive/directory containing the disk
image file you're interested in and
highlight it. Press F1 to "Examine"
the disk image and see it's directory.
This is equivalent of LOAD "$",8 LIST.
Now highlight a PRoGram file and hit
ENTER to RUN it.

    Because many disk image files
contain only one program and are
mostly wasted space, they are often
distributed in a compressed format.
The two most common formats are
PK-ZIPed (.ZIP) and "Zip-Coder 64"
(.Z64)

    .ZIP files must be unpacked with
PK-ZIP or WinZip before you can use
them with your emulator. This is the
preferred method of distribution for
.D64 images.

    "Zip-Coder" is a C-64 program
which has been around a LONG time. It
was used to distribute copies of
entire disk sides on the many
Commodore bulletin boards of old.
"Zip-Coder" files are NOT ALWAYS
designated with the .Z64 extension.
You can ALWAYS identify them by the
form they take in the 1541 directory:

    1!name.Z64 PRG
    2!name.Z64 PRG
    3!name.Z64 PRG
    4!name.Z64 PRG

"Zip-Coder" works by reading each
block of a 1541 disk side. The blocks
are lightly compressed using a simple
RLE (Run-Length Encoding) algorithm
and then divided into four zones. The
zones are defined by the track range
wherein each given block exists. The
size of each of the 1! - 4! files
depends on the number of used blocks
in that zone.

    The four files should be
distributed together. Sometimes they
will be found further packed into
PK-ZIP archives. This two-level
archive means you only have to
download one file, but it is NOT the
best way. It is FAR LESS COMPLICATED
to compress a .D64 image into a .ZIP
archive with PK-ZIP/WinZip. This saves
the user from having to unpack two
levels of archives.

    Several versions of Zip-Coder are
floating around. Most use the same
pack/unpack algorithm and their output
files are interchangeable. A good one
can be gotten from:

  ftp://arnold.c64.org/pub/ut
  ils/c64apps/zippers/

    A good way to eliminate the
complexities of dealing with archives
(especially those nasty two-level
archives) is by installing "Target
D64" by Karlheinz Langguth. It can be
gotten from :

  http://skyscraper.fortunecity.com/
  quadra/251/targetd64.html

    "Target D64" is a PC program which
automatically unpacks the most common
archives used with C-64 image files.
It will start your emulator and
hand-off the resultant image to it. I
use "Target D64" to start .ZIP and
.Z64 compressed images with its "Send
To" context menu. Installing "Target
D64" may require you to edit your PC's
"AUTOEXEC.BAT" file, but all the
details are thoroughly described in
its instructions. Sorry but PC
programs are not nearly as easy to
install and operate as C-64 programs
;')

    Again, see  "FORMATS.ZIP" by Peter
Schepers for the details of the most
common disk image and archive formats.


JOYSTICKS

    Like the other hardware commonly
found on C-64 systems, the joysticks
must be emulated. The easiest joystick
setup available under CCS64 is the
predefined joystick keysets. They work
by intercepting keypresses on the PC
keyboard and passing them to the
emulated C-64 as actions on a joystick
connected to port 1 or port 2.

    Enter the "Input" menu with ALT-I.
Highlight the "Control Port 1"
function and use left-arrow/ right-
arrow to select the "Joystick"
setting. Notice that its also possible
to connect a virtual mouse and virtual
paddles to the emulated machine.

    For now, just select "Joystick".
Now highlight the "Mode" function
corresponding to "Control Port 1" and
select the "Keyset 1" setting. Next,
do the same operations for "Control
Port 2" but select the "Keyset 2"
setting for the "Control Port 2"
"Mode" function.

    View the definitions for each
keyset by highlighting the "Define
Joystick Keyset" function and pressing
right-arrow. Use the "Define Joystick
Keyset" menu to view the key
definitions for "Keyset 1" and "Keyset
2". Later you can re-define the
keysets to your liking, but don't
change them at this time. The default
joystick keyset definitions are:

Keyset 1
  Up = /
  Down = 5
  Left = 7
  Right = 9
  Fire = right ALT

Keyset 2
  Up = 8
  Down = 2
  Left = 4
  Right = 6
  Fire = right CTRL

    These refer to the numeric keypad
on the PC keyboard. You'll see that
the default keysets are very intuitive
as long as you have set the "Control
Port 1" function to "Keyset 1" and the
"Control Port 2" function to "Keyset
2". The default keysets don't work
well for games requiring 2 joysticks
and you'll want to use different
"Mode" settings for these games.

    It is also possible to use a PC
joystick or real C-64/Atari joystick
which has been modified to connect to
the PC. If you have such hardware,
just select the corresponding Mode
setting in the Control Port used by
your game. The plans for such a hack
may be found at:

http://www.students.tut.fi/^kosolah
/joyport/joyport-en.html

 K"PD"K