diff options
Diffstat (limited to 'src/alf.rst')
| -rw-r--r-- | src/alf.rst | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/src/alf.rst b/src/alf.rst index 267f993..f265697 100644 --- a/src/alf.rst +++ b/src/alf.rst @@ -95,7 +95,7 @@ OPTIONS tables (*lots* of output; for debugging only). -V, --version - Show **unalf** version number and exit. + Show **alf** version number and exit. .. show version number. @@ -175,13 +175,29 @@ old disk images as **UNALF.COM**, and **LZ.COM** is sometimes called out of respect for the original author, and partly to avoid confusion between my **alf**\/**unalf** and his Atari ones. +Compression Characteristics +--------------------------- + +Larger files compress better than smaller ones. Very small files +will get larger when compressed. Files with lots of entropy (random +garbage, files that are already compressed) will also get larger. + +For text files, compression is usually around 45% to 50%, which +is comparable with **arc**. For SAVEd Atari BASIC, the average is +a little worse: 35% to 40%. For executables, it seems to average +around 30%... unless the executables are already compressed (e.g. +self-decompressing), in which case they'll get bigger when compressed +with **alf**. + File Size Limits ---------------- -**alf** (and **LZ.COM**) have a 16MB file size limit. **uanlf** -actually can't handle files above about 15MB, if you compress one with -**alf**. Real Atari 8-bit files are never this large anyway, so it's -a pathological case. A real Atari would take hours or even days to +**alf** (and **LZ.COM**) have a 16MB file size limit. This applies to +both the input file size, and the compressed size (in case of files +that grow when compressed, e.g. random data). + +Real Atari 8-bit files are never this large anyway, so it's a +pathological case. A real Atari would take hours or even days to compress/decompress such files, and you'd have to have a hard disk and a DOS capable of handling multi-megabyte files... |