Update notes in alf man page.

2 files changed, 30 insertions, 2 deletions

diff --git a/src/alf.1 b/src/alf.1
index 21c84f4..4c57d03 100644
--- a/src/alf.1
+++ b/src/alf.1
@@ -77,6 +77,7 @@ Success.
 Fatal error (I/O or bad command\-line arguments).
 .UNINDENT
 .SH NOTES
+.SS Compatibility
 .sp
 This \fBalf\fP is \fIintended\fP to be 100% compatible with the original
 Atari \fBLZ.COM\fP aka \fBALF.COM\fP, with the following differences:
@@ -88,11 +89,15 @@ must be given as command\-line arguments.
 \fBLZ.COM\fP always appends to a file that already exists. This \fBalf\fP
 overwrites (making a backup) by default, and can append with the \fB\-a\fP
 option.
+.IP \(bu 2
+Turning the screen off for speed makes no sense on modern operating
+systems, so there\(aqs no option for that.
 .UNINDENT
 .sp
 Note that \fBalf\fP is a complete reverse\-engineered rewrite in C, \fInot\fP
 a port of the original 6502 code as \fBunalf\fP is. It\(aqs still being
 tested, and may still contain bugs.
+.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
@@ -101,14 +106,19 @@ 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...
 .sp
+It\(aqs also impossible to compress empty (0\-byte) files. \fBalf\fP will
+skip them, if any are found.
+.SS Performance
+.sp
 Performance is \fIhorrible\fP\&. This shouldn\(aqt be a real problem on
 modern multi\-GHz CPU, especially since most Atari 8\-bit files are
 small (usually under 64KB). Interestingly, it\(aqs not O(n^2), it scales
 linearly, O(1): Compressing a 1.3MB text file takes 0.7 seconds on the
 author\(aqs (rather modest) Intel i7 workstation, and a file 10x as large
 takes approximately 10x as long (7 seconds). A 50KB file is almost
-instantaneous, 0.5 seconds, which is more typical of the files you\(aqd
+instantaneous, 0.05 seconds, which is more typical of the files you\(aqd
 actually use this with.
+.SS Timestamps
 .sp
 The date/time stamps stored in the archive are the \fBmtime\fPs of
 the files (which is the same time \fBls\fP(1) shows, by default), and
diff --git a/src/alf.rst b/src/alf.rst
index bb55282..8108d7d 100644
--- a/src/alf.rst
+++ b/src/alf.rst
@@ -67,6 +67,9 @@ EXIT STATUS
 NOTES
 =====
 
+Compatibility
+-------------
+
 This **alf** is *intended* to be 100% compatible with the original
 Atari **LZ.COM** aka **ALF.COM**, with the following differences:
 
@@ -77,10 +80,16 @@ Atari **LZ.COM** aka **ALF.COM**, with the following differences:
   overwrites (making a backup) by default, and can append with the **-a**
   option.
 
+- Turning the screen off for speed makes no sense on modern operating
+  systems, so there's no option for that.
+
 Note that **alf** is a complete reverse-engineered rewrite in C, *not*
 a port of the original 6502 code as **unalf** is. It's still being
 tested, and may still contain bugs.
 
+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
@@ -88,15 +97,24 @@ 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...
 
+It's also impossible to compress empty (0-byte) files. **alf** will
+skip them, if any are found.
+
+Performance
+-----------
+
 Performance is *horrible*. This shouldn't be a real problem on
 modern multi-GHz CPU, especially since most Atari 8-bit files are
 small (usually under 64KB). Interestingly, it's not O(n^2), it scales
 linearly, O(1): Compressing a 1.3MB text file takes 0.7 seconds on the
 author's (rather modest) Intel i7 workstation, and a file 10x as large
 takes approximately 10x as long (7 seconds). A 50KB file is almost
-instantaneous, 0.5 seconds, which is more typical of the files you'd
+instantaneous, 0.05 seconds, which is more typical of the files you'd
 actually use this with.
 
+Timestamps
+----------
+
 The date/time stamps stored in the archive are the **mtime**\s of
 the files (which is the same time **ls**\(1) shows, by default), and
 your local timezone is assumed. Only a 2-digit year is displayed by