PC Home 32/PC_HOME_95-uncompressed-cd-image.iso/general/xform/xform.exe/XF251.DOC

Text File | 1995-01-12 | 17.9 KB | 426 lines

PC Xformer 2.51 - The Atari 800/800XL Emulator For MS-DOS Compatible PCs
========================================================================

January 13, 1995.

Branch Always Software
14150 N.E. 20th Street
Suite 302
Bellevue, WA  98007
U.S.A.

Program by Darek Mihocka. Many thanks to Danny Miller and Bob Woolley for
their beta testing and technical help, to Greg Tibbets for the many Rana
drives, to Jan Gray for sharing cool programming tricks, to Bill Kendrick
for writing the very cool manual for 3.0, and to Nick Kennedy for developing
the SIO2PC cable which makes life so much easier.


Copy this program!
------------------

PC Xformer 2.51 is a free emulator for MS-DOS users who wish to run their old
Atari 400/800 and Atari 800XL software on their PCs. The file XF251.ZIP may be
freely redistributed under the condition that the contents of the ZIP file are
not modified in any way, and that no fee is charged for the software other than
reasonable long distance and online charges for downloads.

These files must be present in the XF251.ZIP archive:

    XF251.EXE    - an MS-DOS program that is the PC Xformer 2.51 emulator
    XF251.DOC    - this documentation file
    DOS25.XFD    - ST Xformer disk image containing Atari DOS 2.5 files
    MYDOS45D.ATR - SIO2PC disk image containing MyDOS 4.5 files
    ATARIOSB.ROM - Atari 800 operating system
    ATARIXL.ROM  - Atari 800XL operating system
    ATARIBAS.ROM - Atari Basic
    DEMOS1.XFD   - disk image containing Atari 800XL BASIC demos
    DEMOS2.XFD   - disk image containing Atari 800XL machine language demos


Quick Start
-----------

If you have previously used PC Xformer 2.0, then using 2.51 is exactly the same!
The only new key you have to learn is F12, describled below, and F5 is now
Shift+F5. Otherwise, everything will work as before, only better!

To just quickly run PC Xformer 2.51, type XF251 from the DOS prompt. The
familiar blue and white Atari Basic screen will appear with the READY prompt.
Type in a small Basic program and you'll see it's just like an Atari 400/800
or 800XL!

Use the F12 key on the PC's keyboard to switch between Atari 800XL mode and
Atari 800 mode. The current mode is displayed at the bottom of the screen.

Use the F10 key to "system reset". Press F10 while holding the Shift key to
toggle Atari Basic on or off.

In Atari 800XL mode you have access to the new graphics modes (GR.9 through
GR.15), plus you can run the newer software designed for the 800XL. Switch
back to Atari 800 mode to run older software.

Press Shift+F5 (that is, press and hold the Shift key then press the F5 key)
to exit back to the DOS prompt. Then read the rest of this document!


Hardware requirements
---------------------

PC Xformer 2.51 is a 16-bit MS-DOS application. It is designed to run on most
PCs with minimum hardware requirements. It requires only a 286 compatible CPU,
so it is compatible with all 286, 386, 486 and Pentium based PC, as well as any
PC that can emulate the 286. For example, the Mac running SoftAT, the PowerMac
running SoftWindows, and any Windows NT based RISC machine.

PC Xformer 2.51 also requires a VGA compatible display, and about 300K of RAM.


Installing Disks
----------------

PC Xformer 2.51 uses the same 90K, 130K, and 180K disk images used by our
older ST Xformer 8-bit emulator, and it also supports reading and writing
to SIO2PC generated disk images.

If you don't know what SIO2PC is, call your Atari dealer and ask. It's a
cool cable that you connect between your real Atari 800 computer and your
PC which allows you to blast over all of your 8-bit disks to your PC and
store them as disk images (the 90K, 130K, or 180K data files).

If you specify virtual disk files and/or MS-DOS files after the XF251, those
will be installed as Atari disk drives. For example, type:

XF251 DOS25.XFD DEMOS1.XFD

to boot up DOS 2.5 from D1: and then access demo files from D2:. Using the
same example, once you are in Atari Basic type:

RUN"D2:ATARI800.BAS"

to run a demo program. Or type DOS to go to the DOS 2.5 file manager.
Machine language programs (typically files ending with .OBJ or .COM) should
be run with Basic disabled by pressing Shift+F10 to reboot without Basic.


Features
--------

Many of the limitations of our old ST Xformer emulator and other clone Atari
emulators have been eliminated in PC Xformer. PC Xformer is written mostly
in machine language and takes full advantage of the PC hardware.

Features common to both PC Xformer 2.51 and PC Xformer 3.0 include:

    - 48K Atari 400/800 emulation

    - 64K Atari 800XL emulation with "RAM under ROM" memory

    - allows user installable patches to the OS and BASIC

    - displays all ANTIC text and graphics modes, including GTIA modes

    - 256 color GTIA color palette

    - player missile graphics

    - horizontal and vertical fine scrolling

    - supports display list interrupts, IRQ, and NMI interrupts

    - reads and writes to ST Xformer and SIO2PC generated disk images

    - reads MS-DOS files directly from within Atari DOS

    - switch Atari BASIC on/off with one keystroke

    - switch between Atari 400/800 and Atari 800XL emulation with one keystroke

    - joystick emulation using the keyboard cursor keys

    - full speed emulation on a 386/33 or faster

    - slow and fast modes of emulation to take advantage of fast PCs

    - compatible with all VGA cards


In addition, PC Xformer 3.0 adds features including these:

    - 130XE emulation with 256K of extended XE memory

    - on-the-fly disk image swapping

    - 4 voices of sound, printer, and modem support

    - real joystick support

    - 386 optimized code for faster speed than PC Xformer 2.51

    - disable Atari BASIC from the command line

    - specify emulation mode from the command line

    - automatically skip the intro screen

    - over 1 megabyte of sample Atari 8-bit programs

    - 40 pages of 8-bit Atari reference documentation


Below is a list of processors and the approximate speed of emulation relative
to an Atari 800:

    - 286/16     - 0.3
    - 386SX/20   - 0.5
    - 386DX/33   - 1.0
    - 486DX/33   - 2.0
    - 486DX2/66  - 4.0
    - Pentium/90 - 8.0

486 and Pentium users can use the slow/fast option to slow down the emulator
to normal Atari 800 speed or let it run as fast as possible.


Upgrading to PC Xformer 3.0
---------------------------

PC Xformer 3.0 can be ordered for $29.95 U.S. directly from Branch Always
Software at the address above, or from these and other fine Atari dealers:

    American Techna-Visions (U.S.A.) phone: [phone]   fax: [phone]
    Atari Bit Byter Club (Germany)   phone: [phone]  fax: [phone]
    B & C Computervisions (U.S.A.)   phone: [phone]   fax: [phone]
    KE-Soft (Germany)                phone: [phone]  fax: [phone]
    Micro Discount (U.K.)            phone: [phone]  fax: [phone]
    Mid Cities Computers (U.S.A.)    phone: [phone]   fax: [phone]
    Rising Star Computers (U.S.A.)   phone: [phone]   fax: [phone]
    Toad Computers (U.S.A.)          phone: 800-448-TOAD   fax: [phone]


The keyboard, cursor keys, and joystick emulation
-------------------------------------------------

All letter and number keys function as on the 800XL keyboard. Punctuation
keys will give the characters shown on the PC keyboard, not the characters
that appear on the Atari keyboard. i.e. Shift+2 gives the @ character, not ".

If you are used to using the Atari keyboard and want keys to work as they
do on the Atari keyboard, keep in mind that PC keyboards come in every style
and layout and so it is impossible to do that. Simply spend a few minutes
looking at they keys as you type and you will get used to your particular
PC's keyboard layout.

F1 F2 F3 F4 function as cursor keys (up, down, left, right), similar to the
four function keys on a 1200XL.

Shift+F5 exits back to DOS. Remember this when you want to exit PC Xformer!!

F6 is the HELP key.

F7 is the START key.

F8 is the SELECT key.

F9 is the OPTION key.

F10 is RESET. Press Shift+F10 to reset and toggle Basic on or off.

F12 switches between emulating an Atari 800XL and an Atari 400/800.

Insert and Delete insert and delete a character.

Shift+Insert and Shift+Delete insert and delete a line of text.

Home is the CLEAR key.

End is the BREAK key.

Ctrl+End is the equivalent of Ctrl+3 (end of file key)

The ` key is the Atari logo key used to toggle inverse text on/off.

Page Up and Page Down are used to move the display window up or down a pixel
at a time. This allows you to center the screen for programs whose display
extends either too far up or too far down.

The numeric keypad functions in two modes. When the Num Lock is set, the
numeric keypad produces numbers. When Num Lock is not set, the keys 2 4 6 8
function as a 4 direction joystick. 0 on the keypad is the fire button.

If your keyboard has an "inverted T" set of cursor keys, those also function
in two modes. By themselves they function as a 4 direction joystick. When
pressed with the Ctrl key, they act as cursor keys (same as F1 F2 F3 F4).

Due to differences in the layout of the Atari 800XL and PC keyboards,
the keys + - = * do not function as cursor keys. You must use F1 F2 F3 F4 or
the PC's cursor keys.

Some PC keyboards have an 8-way set of cursor keys, containing the usual
up down left and right cursor keys, plus four diagonal keys. Pressing those
diagonal keys will generate diagonal joystick movements as expected.

Pressing Ctrl and a letter key will give you the graphics characters as on
the Atari 800XL. However, the two graphics characters produced by pressing
Ctrl+, and Ctrl+. can be obtained on the PC keyboard by typing Ctrl+[ and
Ctrl+].

Caps Lock functions as the Atari's Caps key, not as a true Caps Lock. Press
Caps Lock once to enter lower case mode, then press Shift+Caps Lock to go
back to upper case mode.

Scroll Lock toggles fast/slow mode. Scroll Lock on is the slow mode. Use this
feature only on 486 and Pentium machine. On slower machines it will cause the
emulator to slow down too much. See below.

To pause a program or a listing, press the PC's Pause key instead of Ctrl+1.

In place of Ctrl+3 press break.

Ok, got that? Just spend a few minutes playing around with the PC's keyboard
and things will start to make sense.


Slow/Fast modes
---------------

Scroll Lock toggles the slow/fast speed of the emulator. By default the
emulator is in fast mode, meaning it runs as fast as possible. On a 286 or
386 based PC, PC Xformer 2.51 should run at or slightly below the speed of an
8-bit Atari so leave it in the default setting. On a 486 or Pentium, the speed
may be too fast for some games, although the faster speed may be just what is
needed for some slow BASIC games. In any case, if you do need to slow down the
emulator, activate Scroll Lock to place the emulator into slow speed mode.
At this point the emulator "applies the brakes" and attempts to drop down to
about normal speed. Press Scroll Lock again to switch back to fast mode.


Disk drive emulation
--------------------

Now we come to what to some people is the most confusing part about using an
emulator, whether PC Xformer, ST Xformer, DOS emulators on UNIX, or the many
different Apple II emulators out there - disks. It's quite simple once you
understand the concepts so let me try to explain.

With Gemulator I lucked out. Both the Atari ST and most PCs use the exact same
3.5 inch floppy disks and they even format the disks the exact same way. What
that means to you is that you can take a disk from an Atari ST and just pop
it into a PC and just read the files directly. No special cables, no special
adjustments to your disk drive.

Not so with most computers. A PC's 5.25" floppy disk drive can't directly
read an Apple II's 5.25" floppy disks. An old Mac II can't directly read
Atari ST disks. And of course, the bummer, a PC's 5.25" floppy disk drive
can't read Atari 8-bit floppy disks.

So what to do? The same problem existed on the Atari ST with ST Xformer. I
tried several different techniques. ST Xformer 1.0 emulated Atari DOS and
faked up the D: device, so that whatever filename you specified actually
accessed that file on the Atari ST's disk. ST Xformer II did the same thing
but called it the F: device.

Unfortunately most (well, a lot) of Atari 8-bit software bypasses Atari DOS
and read sectors from the disk directly. So the F: thing doesn't work too well
for them, or boot disk that don't use a DOS at all.

So I did what all of the Apple II emulators and most other emulators do: use
virtual disks. A virtual disk is just a large data file that contains all the
information of a single floppy disk.

A virtual disk containing all the information of an Atari 8-bit single density
disk must hold all the information from the 720 sectors on that disk. At
128 bytes per sector, 720*128 = 92160 bytes. And that is exactly how large
ST Xformer virtual disk files are. 92160 bytes. Every byte in the file
corresponds to a byte originally found on the disk.

The question still remains how to create a virtual disk file. Shortly after
releasing ST Xformer II, I realized that the Atari ST's parallel printer port
is very much like the Atari 800's serial port. One has 25 pins, the other has
13 pins. Big deal. What the pins do is very similar, and so I developed a
cable known as the ST Xformer Cable (what else!) which allowed you to directly
connect an Atari 810 or 1050 disk drive to the Atari ST. Then using some
software, the ST read each of the 720 sectors on the Atari 8-bit disk and
stored those 92160 bytes into a file (usually with a .SD or .XFD extender).

And that is how you create a virtual disk on the Atari ST. If you are an Atari
ST user and have user ST Xformer II in the past, then all of your Atari 8-bit
software is already in virtual disk format and ready for use on PC Xformer!

If not, and you don't know any Atari ST users who have the ST Xformer Cable,
don't despair. There are still plenty of ways to transfer a file to the PC.

About 4 years ago an Atari user by the name of Nick Kennedy tackled exactly
this problem. And he developed a cable called the SIO2PC cable, to directly
connect an Atari 8-bit computer to the PC.

Now of course he had no clue that 4 years later someone would come around and
write an emulator, so the reason for his cable was to use a PC with its big
PC hard disk to store Atari 8-bit files. Basically, using a PC as a very large
hard disk for an Atari 800. By daisy chaining both a PC as well as a real
Atari 8-bit disk drive onto the cable you are then able to copy files from
the 8-bit disk drive to the PC.

As it happens, guess how the SIO2PC software stores the 8-bit files on the PC
once they're transfered over the cable? In virtual disks of course! In fact,
virtual disks created by SIO2PC are almost identical to those created by
the ST Xformer cable, and so PC Xformer 2.51 supports both types of virtual
disk files. (The difference is an extra 16 byte header that SIO2PC uses).

The SIO2PC cable has been around for 4 years and is fairly well known in
the Atari 8-bit community, so this document will not describe how to build
or use the SIO2PC cable. Contact your local Atari dealer, your user group,
download files #5281 and #6414 from the Atari 8-bit roundtable on GEnie, or
best yet, contact Nick Kennedy directly at 501-967-3843 or write to him at:

Nick Kennedy
300 South Vancouver St.
Russellville, AR  72801

There is one other very common way to transfer a file between any two
computers, and that is to use a null modem cable or two modems. Whenever you
call a BBS with your modem and download a file, you are transfering a file
from one computer (whether it be a PC or Mac or ST) to another.

There are thousands of public domain and shareware Atari 8-bit programs
available for download from BBSs and online services. Download these files
to your PC using whatever DOS or Windows based terminal software you normally
used (that's most likely how you obtained this copy of PC Xformer 2.51)

Once the file is on your PC, copy it to the same directory that you run
PC Xformer 2.51 from. Then specify the file on the XF251 command line as the
second file. For example, let's say you downloaded a file called BUDGET.BAS.
Typing this:

XF251 DOS25.XFD BUDGET.BAS

causes PC Xformer 2.51 to boot up using DOS25.XFD as drive D1:, and the file
BUDGET.BAS will appear as the only file on drive D2:. Then using DOS 2.5
(or any other Atari DOS) copy the file from D2: to D1: so that it is now
on a virtual disk. You want to eventually copy all your Atari 8-bit files into
virtual disk image files.

PC Xformer 2.51 allows for up to 8 files to be specified on the XF251 command
line. The first file MUST be a virtual disk, since it must contain a valid
DOS on it to install as drive D1:. The remaining 7 files may either specify
other virtual disk files, or MS-DOS files which will automatically appear
as virtual disks as described above.

Note that by default DOS 2.5 will only access 2 disk drives (D1: and D2:).
See you DOS manual on how to expand that, or use a different DOS (such as
MyDOS 4.5) which supports up to 8 drives.

Note that there is one other method to transfer 8-bit files to the PC. It
seems that the PC's 5.25 inch floppy disk drive actually CAN read Atari disks
if they are formatted double density and you run a special utility. I have not
seen this work reliably, but people claim it works. So try it out if you can.

And now you are set to run PC Xformer 2.51 to your heart's content! But don't
forget to upgrade to PC Xformer 3.0 and have a complete 130XE emulator with
40 pages of reference documentation.

Darek Mihocka, Owner of Branch Always Software
Creator of ST Xformer, Quick ST, PC Xformer, and Gemulator