ZX Pilot #12 09 июля 1997

Софт

about different - On the compression of information on magnetic media.

    About MISC


(C) VELSOFT


   Hello! At this time we will talk about compression of 
information on magnetic media. Virtually all started with a 
Speccy 48k + tape recorder. In those days mainly to compress 
only pictures. Coded files do not compress, and if such and

happened, then compress only the Poles some compressor, which 
compresses zeroes. Times change, and with the advent of disk 
drives has become necessary to compression of information to 
economical use of space. I cooked small survey of the most 
common screens and compressors mashinokodovyh blocks. These 
compressors. 

Compressors display files:
1. Compress v1.0 by?
2. Screen Crasher v2.6 by ASC 1991
3. Compres v1.0 by A. S. Koln 1992
4. Superpak v2.0 by KVR 'VLV 1993
5. Maxsoft Screen Packer v1.0 by Maxsoft 1996
6. Code Cruncher v3.11 by KSA 1996
7. Powerfull Code Decreaser v6.1 by KSA 1996

Compressors mashinokodovyh files:
1. LZSS Pack Game Compressor v4.5 by ASC 1991
2. TRUSH File Compressor v3.8 by Alexander Trush 1992
3. ZYX Compressor Code v4.1 by ZYX 1993
4. Pack 2.2 Beta v2.2 by U. of K. 'PSW 1993
5. Data Squeezer v4.12 by RUSH 1995
6. Code Cruncher v3.11 by KSA 1996
7. MS-PACK v1.0 by Microspace 1996
8. Powerfull Code Decreaser v6.1 by KSA 1996


   Choosing a sufficiently large, agree. Although, generally 
speaking, compressors Speccy there is so much more. We consider 
Only the most popular and common compressors. So, for example 
of the usual on-screen images and conventional block codes, we 
The basic characteristics and the degree of compression of the 
above compressors. 

Compressors display files. Investigated the picture is taken 
from the game Montana Jones 2. Home - 16384, length - 6912.


1. Length after compression of 3966 (16 sectors). Old enough
compressor that was used by such well-known Polish hackers
as Bill Gilbert, Roby etc ... Due to the large decompressor 
(about 300 bytes) compress the block got enough large. The main 
advantage is that the compressor allows you to compress 
individual third of the screen and packing a few pictures at a 
decompressor (call display on his number). There are many other 
service functions. Compression and decompression almost 
instantly (as I recall, this compressor is included in its 
original delivery Artist I on the tape). 

2. Length after compression of 3414 (14 sectors). Perfectly 
acceptable Compressor screens. Compresses the method LZSS and 
has a convenient disc menus with service functions. There is an 
opportunity to work with tape. Speed ​​compression and 
decompression is quite satisfying. 100% safety of your 
pictures. 

3. Length after compression of 3687 (15 sectors). Has four
Compression and choose the most appropriate. Compression is 
fast enough, and decompressor is almost instantaneous. There 
are service functions (viewing pictures, a temporary exit to 
DOS, directory ...). 

4. Length after compression of 3489 (14 sectors). Compression 
of an improved method for LZ. Compress the block does not move 
in memory and the decompressor requires 20kb of free memory 
(4E46E4). Decompressor is not very fast. 

5. Length after compression of 3722 (15 sectors). Ordinary 
compressor display files. There is a convenient disk menu with 
a choice various service functions.


6. Length after compression of 3978 (16 sectors). Enough 
compression braking with constant podzagruzkoy something. 
Compress the block does not move in memory and loaded into the 
screen. Decompression on the screen appears and then disappears 
some colored stuff. 

7. Length after compression of 3715 (15 sectors). Well, just 
very compression brake and the result "surpasses all 
expectations." There have been cases when the program, 
uncompress the picture, just pure and not come out of the 
decompressor. But in fact nothing new This compressor will not 
give you. 

Rem: it's worth noting that the results of compression can
vary somewhat depending on the display file. In fact,
these results are not very big, but who are interested can
to test all compressors.

Compressors mashinokodovyh files. Analyzed unit is taken out of 
the game Quest for Tires. Launch - 24 576, length - 40960.


1. Length after compression 23142 (91 sector). The most 
convenient and fast compressor. Very small decompressor and a 
bunch of auxiliary functions (autostart, interruptions, new 
stack ...). There is an opportunity to work with tape. There is 
a version of the compressor, allowing packing @ files without 
images. 

2. Length after compression 20637 (81 sector). Very brake poll 
the keyboard and absolutely no service. In addition to all that 
you may have problems with the uploading the compressed block, 
if he has too low a load address. 

3. Length after compression 30937 (121 sector). This packer
very large decompressor (700 bytes). Managing prog
written in Basic'e and compression is required at least half
free disk. Compressor 128k only.

4. Length after compression 28902 (113 sectors). Fairly fast 
compressor and decompressor. Depaker takes up very little 
space. Few service functions. 

5. Length after compression 17583 (69 sectors). Quite decent
compressor. Depaker somewhat slow (although there are worse).
Have the necessary service functions.

6. Length after compression 22294 (88 sectors). Outwardly 
similar to the one room but always something loads. Available 
service functions. Depaker medium length. There have been cases 
reset the computer during compression.


7. Length after compression 16792 (66 sectors). Very nice and
easy to use compressor. There are many service functions.
Decompressor fast enough.

8. Length after compression of 9625 (38 sectors). Superficially 
looks like the previous compressor. Available service 
functions. The most interesting thing is that after you unpack 
the program is not something that worked, it never failed to 
start. There is speculation that this compressor correctly 
decompress only small blocks. 

Rem: the results of compression can vary somewhat in
Depending on mashinokodovogo block. All compressors, except for 
numbers 1 and 4, long enough compresses information. Advise 
patience. 


   This concludes our little review of the compressors. You
have the opportunity to choose a favorite compressor. And can 
you be able to invent a new way of compression?