By Shimon Young
The Compressor
Boot up as normal (system 3b or higher with the DISCIPLE) and load the tape from the
beginning. Stop the tape when you are greeted by the scrolling message. This can be stopped
at any time by pressing Break. NB. Make sure you do not reload the program with The
Compressor system file already patched in.
Installation
Once you have stopped it, the DOS in memory will have been patched by the compressor.
You will now need to resave this as your standard system file by typing SAVE
d1”+Syscomp” CODE 8192,6656 on the +D or SAVE d1”Syscomp” CODE 0,6656 on the
DISCIPLE and replace your old system files so it boots up with this. If on the +D, the system
hangs up in snapshot mode, reset and type POKE 6282,8469 and resave the system file.
If you are using a DISCIPLE you will need to save an execute file by typing SAVE
d1”SavePatch” X,49551. The reason for this is explained later. As the compressor routines
overwrite the graphic dump code on the DISCIPLE ie. SAVE SCREEN 1 & 2 you may want
to keep a normal system file around to make screen dumps. If you are using the compressor
system and you want to dump a screen to the printer, press the snapshot button and press ‘3’
to save the screen to disc. Later you can boot up with a normal system and dump it then.
While using the compressor the SAVE SCREEN command will be ignored.
When using the system there is no change in making and loading snapshots. Just follow the
normal procedure for making 48 or 128 snaps. While saving the snap, the screen will corrupt
for a second but will return to normal after. DON’T PANIC! This is supposed to happen.
Operation
Loading snapshots is exactly the same. Just use the normal LOAD commands and the system
will decide if the snap is compressed and load it properly. You can load normal snaps still.
The system will only normally save compressed snaps. You may want to make a normal snap
for a back up or to use with other programs like Tapesnap. If so, on the DISCIPLE load in the
execute file by LOAD d1”SavePatch” X and you will then be only able to save normal snaps
but still load compressed ones. If you need to make compressed snaps again, reload the
system file. If you want to make a normal snap on the +D you can press the snapshot button
and then ‘n’. The +D will pause for a moment and then continue. You can now save a normal
snap or return to the program by pressing ‘x’. Any snaps you now make will not be
compressed. If you want to return to making compressed snaps press ‘c’ instead of ‘n’.
You cannot load compressed snapshots with a normal system file. Any attempt to load a
compressed snap from a normal system file will result in a crash.
When you catalogue the disc, the directory description looks the same except for the number
of sectors used which will vary from snap to snap.
You must be careful if the disk is nearly full as you may not know if the snap has saved. If the
next time you try to make a snap and nothing happens, this probably means the disc is full and
the snap before did not save either. A bug in G(+)DOS has been fixed by the compressor, so
the computer will not crash if the disc is full when making a 128 compressed snap.
The Compressor works by getting rid of consecutive bytes of the same value. These are
usually zeros but the compressor can cope with any value. Therefore it is best to make a snap
on a nearly blank screen like the options screen on a game.
Hints
A few games have some very powerful compressor routines of their own, like Renegade 128.
You can recognise these by a long pause after they have finished loading. The earlier you
snap these after they have loaded the more you will save.
Shimon Young, 21 Colchester Road, Southend-on-Sea, Essex SS2 6HW, (0702) 331218