snaprun - Runs .SNA files on your +3 directly from 720Kb MS-DOS disks.

This program let's you read and run .SNA (z80, xzx, jpp and other) snapshot
files on your Spectrum +3 computer. And that's not all, it lets you run
them from 720Kb MS-DOS disks, which means that you don't have to think
so much about how to transfer the .SNA to something your +3 understands.
And it only corrpts about 62 bytes on the main screen, and you decides in
which 1/3 of the screen should be corrupted.
The only thing that's required is that you _must_ have a 3.5" drive, connected
as your B: drive. You'll find various articles on ftp.nvg.unit.no about how
to do this.

INSTRUCTION:

Insert the MS-DOS disk, containing the .SNA's (up to 14 on each disk) in your
3.5" B:drive. Then load the snaprun program: load "snaprun"
If you load the program without any MS-DOS disk in your B: drive, or there 
wasn't found any *.SNA files on the disk, you'll be prompted for a new disk.

If everything went well, you'll be presented with a list of what .SNA files
that was found on the disk.
Now you can use the keys 'Q' & 'A' to choose and the press 'ENTER' to load
and run. You'll also be able to read the directory of a new disk, if required,
by pressing the 'L' key.
 * NOTE: This program assumes that all the .SNA files are in the root of the 
   disk, which means it ignores and won't read any directories on the disk.
Before loading you'll be prompted for which 1/3 of the screen should be
corrupted, by some neccesary datas for the snaprun program.
During loading a lot of screen corruption occours, but don't worry, when the
.SNA has loaded the main screen is restore, except about 62 bytes in the 1/3
of screen you selected.
If the something goes wrong during loading, or you just choosed the wrong
program you may press 'SPACE' for a reset of the speccy.

 * NOTE: This program will lock your +3 in 48K mode before starting the .SNA
   But some games will _not_ run directly on your spectrum, this is in most
   cases because the I-regs is loaded with 0x39, which in the other speccy's
   leads to a pointer to the address 0xffff. If possible change the program
   so it will load the I-regs with the value 0x3b and in most cases the
   program will now run on your +3 too.
   I did manage, using z80, to get a lot of games running which didn't when
   they was loaded from tape in the first place.
   Another good source on how to patch the programs is:
    - The Spectrum Hackers Guide, written by Richard Swann -
   Who also gave me the idea for making this program, as he did one for the
   +D owners.

FILE:

REAMD       : This file??
snaprun.dsk : disk containg the binaries and loader for snaprun.
              This is a disk-image which can be used with xzx-1.0.1
              or the Amstrad-CPC emulator. You can transfer it to 3" disk
              using CPCtrans which comes with CPCEMU by Marco Vieth.
              It's also possible to transfer it to 3.5" 706Kb for +3 DOS,
              using the DDtrans from the xzx packages.
              If you use DDtrans, you must copy this disk to '70bKb format',
              and then use DDtrans to dump the disk-image to a real 3.5" disk.
snaprun.src : Source for the MS-DOS filename viewer, and the filename selector.
              Since all the +3DOS specific routines are at the bottom, it
              should be easy to transfer this part for e.g. +D users.
snap0.src   : The code loader, moves the routine to their right locations.
              and starts the loader.
snap1.src   : Loads the .SNA.
snap2.src   : Moves the .SNA header and restores some registers.
snap3.src   : Locks the +3 in 48K mode, and restores rest of the registers,
              and hopefully starts the .SNA

The description in snap?.src may not be correct for the part, as I had move
move things around the sources.

Sep-94 Thomas Kjaer
takjaer@daimi.aau.dk