unalf: Fix 15MB bug.

1 files changed, 20 insertions, 6 deletions

diff --git a/src/alf.1 b/src/alf.1
index 371f903..53af9a8 100644
--- a/src/alf.1
+++ b/src/alf.1
@@ -27,7 +27,7 @@ level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
 .\" new: \\n[rst2man-indent\\n[rst2man-indent-level]]
 .in \\n[rst2man-indent\\n[rst2man-indent-level]]u
 ..
-.TH "ALF" 1 "2025-12-02" "0.3.0" "Urchlay's Atari 8-bit Tools"
+.TH "ALF" 1 "2025-12-03" "0.3.0" "Urchlay's Atari 8-bit Tools"
 .SH NAME
 alf \- create Atari 8-bit ALF archives
 .\" RST source for alf(1) man page. Convert with:
@@ -121,7 +121,7 @@ Can be given twice for more detail, or 3 times to dump the token
 tables (\fIlots\fP of output; for debugging only).
 .TP
 .B  \-V\fP,\fB  \-\-version
-Show \fBunalf\fP version number and exit.
+Show \fBalf\fP version number and exit.
 .UNINDENT
 .\" show version number.
 .
@@ -197,12 +197,26 @@ old disk images as \fBUNALF.COM\fP, and \fBLZ.COM\fP is sometimes called
 \fBALF.COM\fP or \fBALFER.COM\fP\&. I\(aqve used the original names partly
 out of respect for the original author, and partly to avoid confusion
 between my \fBalf\fP/\fBunalf\fP and his Atari ones.
+.SS Compression Characteristics
+.sp
+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.
+.sp
+For text files, compression is usually around 45% to 50%, which
+is comparable with \fBarc\fP\&. 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\(aqll get bigger when compressed
+with \fBalf\fP\&.
 .SS File Size Limits
 .sp
-\fBalf\fP (and \fBLZ.COM\fP) have a 16MB file size limit. \fBuanlf\fP
-actually can\(aqt handle files above about 15MB, if you compress one with
-\fBalf\fP\&. Real Atari 8\-bit files are never this large anyway, so it\(aqs
-a pathological case. A real Atari would take hours or even days to
+\fBalf\fP (and \fBLZ.COM\fP) 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).
+.sp
+Real Atari 8\-bit files are never this large anyway, so it\(aqs a
+pathological case. A real Atari would take hours or even days to
 compress/decompress such files, and you\(aqd have to have a hard disk and
 a DOS capable of handling multi\-megabyte files...
 .SS Performance