From e9d1cc997a2e6f8a54974c832182aaa9a5f15939 Mon Sep 17 00:00:00 2001 From: "B. Watson" Date: Wed, 26 Nov 2025 17:53:35 -0500 Subject: Update notes in alf man page. --- src/alf.1 | 12 +++++++++++- src/alf.rst | 20 +++++++++++++++++++- 2 files changed, 30 insertions(+), 2 deletions(-) (limited to 'src') 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 -- cgit v1.2.3